(Radiographics. 2002;22:543-561.)
© RSNA, 2002
Emphysematous Infections of the Abdomen and Pelvis: A Pictorial Review1
David E. Grayson, Capt, USAF, MC,
Robert M. Abbott, Lt Col, USAF, MC,
Angela D. Levy, Lt Col, USA, MC and
Paul M. Sherman, Maj, USAF, MC
1 From the Department of Radiology, Wilford Hall Medical Center, 759th MDTS/MTRD, 2200 Bergquist Dr, Suite 1, Lackland AFB, TX 78236-5300 (D.E.G., R.M.A., P.M.S.); the Department of Radiology, University of Texas Health Science Center, San Antonio (R.M.A.); the Department of Radiologic Pathology, Armed Forces Institute of Pathology, Washington, DC (A.D.L); and the Department of Radiology and Nuclear Medicine, Uniformed Services University of the Health Sciences, Bethesda, Md (A.D.L.). Presented as an education exhibit at the 2000 RSNA scientific assembly. Received August 7, 2001; revision requested October 8 and received November 7; accepted November 7. Address correspondence to D.E.G. (e-mail: dgrayson@satx.rr.com).
 |
Abstract
|
|---|
Emphysematous (gas-forming) infections of the abdomen and pelvis represent potentially life-threatening conditions that require aggressive medical and often surgical management. The initial clinical manifestation of these entities may be insidious, but rapid progression to sepsis will occur in the absence of early therapeutic intervention. Conventional radiography and ultrasonography are often the initial imaging modalities used to evaluate patients with abdominopelvic complaints. However, when a differential diagnosis remains, or if further localization or confirmation of tentative findings is needed, computed tomography (CT) should be considered the imaging modality of choice. CT is both highly sensitive and specific in the detection of abnormal gas and well suited to reliable depiction of the anatomic location and extent of the gas. Of equal importance may be the capability of CT to help reliably identify benign sources of gas, because treatment (if any) varies dramatically depending on the source. Knowledge of the pathophysiologic characteristics, common predisposing conditions, and typical imaging features associated with gas-forming infections of the gallbladder, stomach, pancreas, and genitourinary system will help make early diagnosis and successful treatment possible. In addition, such knowledge will aid in further diagnostic work-up, surveillance of potential complications, and evaluation of therapeutic response.
© RSNA, 2002
Index Terms: Cholecystitis, 76.284 • Cystitis, 80.218 • Emphysema, gastrointestinal, 72.291, 76.284, 77.291 • Gastritis, 72.291 • Genitourinary system, infection, 80.21 • Pancreatitis, 77.291 • Scrotum, diseases, 847.2111
|
LEARNING OBJECTIVES
|
|---|
After reading this article and taking the test, the reader will be able to:
- Discuss the clinical features and predisposing conditions associated with emphysematous infections of the abdomen and pelvis.
- Describe the characteristic radiologic features of emphysematous infections involving the gallbladder, stomach, pancreas, and genitourinary system.
- Recognize the typical radiologic appearances of clinically benign sources of gas.
|
Introduction
|
|---|
The presence of gas within the parenchyma of solid organs or the walls of hollow viscera may be due to a variety of pathologic or benign entities. Besides infection with gas-forming bacteria, other possible sources include bland tissue infarction with necrosis, enteric fistula formation, and reflux from an adjacent hollow viscus. Gas should be differentiated from atmospheric air introduced at recent instrumentation or surgery. Gas associated with infection is generally thought to consist of carbon dioxide and nitrogen secondary to the fermentation of glucose by some species of bacteria. Poor glycolysis at the tissue level in diabetic patients results in increased glucose concentrations within the interstitial fluid. Other clinical factors that contribute to the increased production or slowed removal of gas include a depressed cell-mediated immune response, local tissue necrosis, and the presence of arteriosclerosis (1,2). The increased pH of bile associated with gallbladder inflammation and the focal tissue ischemia seen in gynecologic neoplasms are examples of specific underlying processes that help optimize bacterial culture media (2,3). In addition to broad-spectrum antimicrobial therapy and possible surgery, correction of associated underlying conditions such as urinary outflow obstruction, acid-base and electrolyte imbalances, hypovolemia, and hyperglycemia is imperative.
In the setting of gas-forming infections, clinical outcome will, in large part, depend on whether early diagnosis and treatment are achieved. The presence of comorbid conditions and equivocal physical examination findings may prevent rapid diagnosis or delay appropriate initial therapy. Consequently, appropriate radiologic imaging with prompt, accurate interpretation plays an important role in the diagnosis and management of these diseases.
In this article, we review gas-forming infections of the gallbladder, stomach, pancreas, and genitourinary system in terms of radiologic features, clinical manifestations, predisposing factors, differential diagnoses, and current management options. These infections include emphysematous cholecystitis, emphysematous gastritis, emphyse-matous pancreatitis, emphysematous pyelonephritis, emphysematous pyelitis, emphysematous cystitis, gas gangrene of the uterus, and Fournier gangrene.
|
Emphysematous Cholecystitis
|
|---|
Emphysematous cholecystitis is a rare form of acute cholecystitis whose radiographic appearance was first described in 1931 by Hegner (4). Men are affected twice as commonly as women, whereas the reverse is true in most cases of acute cholecystitis (5). The majority of patients are between 50 and 70 years of age and have underlying diabetes mellitus and peripheral atherosclerotic disease. Vascular compromise of the cystic artery is thought to play a significant role in the evolution of the emphysematous form of this disease, likely explaining its male predilection (3,5–7). In comparison with all cases of acute cholecystitis, emphysematous cholecystitis is associated with an increased prevalence of acalculous disease and gallbladder perforation (5). Clinical manifestation is often insidious and may then progress rapidly, requiring emergent surgical intervention. Commonly isolated organisms include Clostridium welchii and Escherichia coli (5,6).
Staging of emphysematous cholecystitis with conventional radiography has been previously described (8). Stage 1 emphysematous cholecystitis is characterized by gas within the gallbladder lumen; stage 2, by gas with in the gallbladder wall; and stage 3, by gas within the pericholecystic tissues. In the absence of clear delineation of the gallbladder by intramural gas (Fig 1), the differential diagnosis for an area of hyperlucency seen in the right upper quadrant at conventional radiography should include overlying bowel gas, hepatic abscess, retroperitoneal air, enterobiliary fistula, gallstone ileus, incompetent sphincter of Oddi, and focal biliary lipomatosis (Fig 2) (3).
View larger version (157K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1a. Stage 2 emphysematous cholecystitis. (a) Abdominal radiograph obtained in a 78-year-old diabetic man demonstrates gas within the gallbladder wall (arrows). (b) Photograph of the cut gross specimen shows areas of transmural infarction (arrows) and hemorrhagic necrosis (*). (c) Radiograph obtained in a different patient shows intramural gas that delineates the characteristic gallbladder shape (arrowheads). (d) Photomicrograph reveals diffuse edema, foci of hemorrhage (short arrows), and multiple cystic gas collections (long arrows) in the gallbladder wall.
|
|
View larger version (141K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1b. Stage 2 emphysematous cholecystitis. (a) Abdominal radiograph obtained in a 78-year-old diabetic man demonstrates gas within the gallbladder wall (arrows). (b) Photograph of the cut gross specimen shows areas of transmural infarction (arrows) and hemorrhagic necrosis (*). (c) Radiograph obtained in a different patient shows intramural gas that delineates the characteristic gallbladder shape (arrowheads). (d) Photomicrograph reveals diffuse edema, foci of hemorrhage (short arrows), and multiple cystic gas collections (long arrows) in the gallbladder wall.
|
|
View larger version (129K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1c. Stage 2 emphysematous cholecystitis. (a) Abdominal radiograph obtained in a 78-year-old diabetic man demonstrates gas within the gallbladder wall (arrows). (b) Photograph of the cut gross specimen shows areas of transmural infarction (arrows) and hemorrhagic necrosis (*). (c) Radiograph obtained in a different patient shows intramural gas that delineates the characteristic gallbladder shape (arrowheads). (d) Photomicrograph reveals diffuse edema, foci of hemorrhage (short arrows), and multiple cystic gas collections (long arrows) in the gallbladder wall.
|
|
View larger version (188K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1d. Stage 2 emphysematous cholecystitis. (a) Abdominal radiograph obtained in a 78-year-old diabetic man demonstrates gas within the gallbladder wall (arrows). (b) Photograph of the cut gross specimen shows areas of transmural infarction (arrows) and hemorrhagic necrosis (*). (c) Radiograph obtained in a different patient shows intramural gas that delineates the characteristic gallbladder shape (arrowheads). (d) Photomicrograph reveals diffuse edema, foci of hemorrhage (short arrows), and multiple cystic gas collections (long arrows) in the gallbladder wall.
|
|
View larger version (170K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2a. Hepatic abscess in an intensive care patient with fever and abdominal pain. (a) Digital scout image from an abdominal computed tomographic (CT) scan shows a well-defined collection of mottled gas overlying the right upper quadrant (arrows). (b) Unenhanced axial CT scan obtained at the same level reveals air within a pyogenic hepatic abscess (arrows).
|
|
View larger version (176K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2b. Hepatic abscess in an intensive care patient with fever and abdominal pain. (a) Digital scout image from an abdominal computed tomographic (CT) scan shows a well-defined collection of mottled gas overlying the right upper quadrant (arrows). (b) Unenhanced axial CT scan obtained at the same level reveals air within a pyogenic hepatic abscess (arrows).
|
|
Ultrasonography (US) may demonstrate highly echogenic reflectors with low-level posterior shadowing and reverberation artifact ("dirty" shadowing) emanating from the gallbladder wall or lumen (Fig 3a, Fig 3b). A more specific, though less common, finding consists of small, nonshadowing echogenic foci rising up from the dependent portions of the gallbladder lumen, similar to effervescing bubbles in a glass of champagne ("champagne sign") (Fig 3c) (9,10). US is less sensitive and specific than radiography or CT in the detection of gas. A false-negative result may occur if surrounding pericholecystic air obscures the gallbladder or mimics adjacent air-filled bowel (3). In addition, US of the calcified walls seen in porcelain gallbladder or multiple stones within a contracted gallbladder may have a similar appearance. If emphysematous cholecystitis is suspected at US, additional radiography is recommended to confirm the presence of gas. CT is the most sensitive and specific imaging modality for identifying gas within the gallbladder lumen or wall (Fig 4). Intravenously and orally administered contrast agents are usually not required, and free intraperitoneal air, pneumobilia (Fig 5), and portal venous gas are reliably identified. The presence of pneumoperitoneum indicates perforation, which requires emergent surgical intervention (7,11). Hepatobiliary nuclear imaging may demonstrate nonvisualization of the gallbladder, along with a region of increased hepatic activity adjacent to the gallbladder fossa ("rim sign") (Fig 6) (12,13). This finding is highly specific for advanced or complicated acute cholecystitis, and further radiography may be performed to confirm fulminant gangrenous change.
View larger version (169K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3a. Emphysematous cholecystitis in a 49-year-old diabetic man with a 2-day history of substernal pain and fever. (a) Transverse US image through the gallbladder fossa demonstrates a curvilinear collection of high-amplitude echoes (arrowheads) with posterior dirty shadowing (arrow). (b) Longitudinal US image shows a diffusely echogenic gallbladder wall secondary to intramural gas (arrowheads). (c) US image reveals multiple tiny echogenic reflectors within the gallbladder lumen (arrows) corresponding to gas bubbles arising from the dependent wall (champagne sign).
|
|
View larger version (188K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3b. Emphysematous cholecystitis in a 49-year-old diabetic man with a 2-day history of substernal pain and fever. (a) Transverse US image through the gallbladder fossa demonstrates a curvilinear collection of high-amplitude echoes (arrowheads) with posterior dirty shadowing (arrow). (b) Longitudinal US image shows a diffusely echogenic gallbladder wall secondary to intramural gas (arrowheads). (c) US image reveals multiple tiny echogenic reflectors within the gallbladder lumen (arrows) corresponding to gas bubbles arising from the dependent wall (champagne sign).
|
|
View larger version (185K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3c. Emphysematous cholecystitis in a 49-year-old diabetic man with a 2-day history of substernal pain and fever. (a) Transverse US image through the gallbladder fossa demonstrates a curvilinear collection of high-amplitude echoes (arrowheads) with posterior dirty shadowing (arrow). (b) Longitudinal US image shows a diffusely echogenic gallbladder wall secondary to intramural gas (arrowheads). (c) US image reveals multiple tiny echogenic reflectors within the gallbladder lumen (arrows) corresponding to gas bubbles arising from the dependent wall (champagne sign).
|
|
View larger version (151K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4a. Emphysematous cholecystitis. (a) Unenhanced CT scan through the upper abdomen demonstrates predominantly intramural gas collections (arrows). (b) Unenhanced CT scan obtained in a different patient clearly shows intramural (white arrows) and intraluminal (*) gas. A right renal cyst is incidentally seen (black arrow).
|
|
View larger version (157K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4b. Emphysematous cholecystitis. (a) Unenhanced CT scan through the upper abdomen demonstrates predominantly intramural gas collections (arrows). (b) Unenhanced CT scan obtained in a different patient clearly shows intramural (white arrows) and intraluminal (*) gas. A right renal cyst is incidentally seen (black arrow).
|
|
View larger version (168K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5a. Emphysematous cholecystitis. (a) Contrast material-enhanced CT scan through the upper abdomen demonstrates gas within the gallbladder wall (black arrows) and lumen (*) and cholelithiasis (white arrow). (b) CT scan obtained cephalad to a shows an area of air attenuation centrally within the liver (white arrow) secondary to associated pneumobilia. A feeding tube is seen within the duodenum (black arrow). (c) Photograph of the gross specimen reveals evidence of perforation within a large area of transmural necrosis (arrows).
|
|
View larger version (155K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5b. Emphysematous cholecystitis. (a) Contrast material-enhanced CT scan through the upper abdomen demonstrates gas within the gallbladder wall (black arrows) and lumen (*) and cholelithiasis (white arrow). (b) CT scan obtained cephalad to a shows an area of air attenuation centrally within the liver (white arrow) secondary to associated pneumobilia. A feeding tube is seen within the duodenum (black arrow). (c) Photograph of the gross specimen reveals evidence of perforation within a large area of transmural necrosis (arrows).
|
|
View larger version (130K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5c. Emphysematous cholecystitis. (a) Contrast material-enhanced CT scan through the upper abdomen demonstrates gas within the gallbladder wall (black arrows) and lumen (*) and cholelithiasis (white arrow). (b) CT scan obtained cephalad to a shows an area of air attenuation centrally within the liver (white arrow) secondary to associated pneumobilia. A feeding tube is seen within the duodenum (black arrow). (c) Photograph of the gross specimen reveals evidence of perforation within a large area of transmural necrosis (arrows).
|
|
View larger version (116K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figures 6. Emphysematous cholecystitis in a 49-year-old man with diffuse abdominal pain. Anterior scintigram from a hepatobiliary study shows a region of increased hepatic activity (arrows) adjacent to the relatively photopenic gallbladder fossa (g) (rim sign). The gallbladder itself is not visualized. Normal bowel activity is present (b). (Fig 6 courtesy of Yong Bradley, MD, Brook Army Medical Center, San Antonio, Texas.)
|
|
Emphysematous cholecystitis is definitively treated with cholecystectomy, although percutaneous cholecystostomy may be used as an initial temporizing procedure in critically ill patients (14). The overall mortality rate for patients with the emphysematous form of cholecystitis is 15%, compared with a rate of less than 4% in uncomplicated cases of acute cholecystitis (5).
|
Emphysematous Gastritis
|
|---|
Of all the hollow viscera, the stomach is the least commonly affected by gas-forming infections (15). Of the 30 reported cases in the literature, caustic ingestion (37%) and alcohol abuse (22%) were found to be the most common causes. Other predisposing conditions include recent gastroduodenal surgery, trauma, and gastric infarction (15–18). Caustic ingestion of acid is thought to promote coagulative necrosis of the gastric lumen, whereas ingestion of an alkaline substance leads to liquefactive necrosis; in either case, the end result is mucosal damage and superinfection with gas-forming bacteria (19,20). There are no predilections with regard to age, sex, or diabetic status (15,19). Clinical manifestation may be dramatic, ranging from acute sepsis to gastric hemorrhage and, rarely, vomiting of the necrotic stomach cast (15,19,21). Early endoscopic evaluation will reveal a "cobblestone" appearance to the gastric mucosa, a finding that represents submucosal blebs of air. Common offending bacteria include E coli, C welchii, and mixed infections with Staphylococcus aureus (15,22).
Characteristic findings may be seen at conventional radiography within the first few days of illness and may persist up to 4 weeks (16). Innumerable bubbles are seen to outline the stomach in a mottled distribution (Fig 7). The gastric folds are thickened due to underlying mucosal edema, which may be diffuse or localized to the greater curvature of the stomach. Fluoroscopic evaluation with water-soluble contrast material was previously used to help confirm an intramural location of abnormal gas. Now, however, CT is considered the modality of choice for detection of intramural gas and evaluation for the presence of pneumoperitoneum or portal venous gas (Fig 8). CT may also demonstrate irregular mucosal fold thickening and may be used to monitor response to treatment or disease progression (19,21,23).
View larger version (184K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7a. Emphysematous gastritis in a 33-year-old man with a history of ethanol abuse. (a) Abdominal radiograph obtained with the patient upright shows mottled and irregular collections of gas within the stomach wall (arrows). An endogastric tube and abdominal surgical clips are also seen. (b) Contrast-enhanced CT scan through the upper abdomen clearly demonstrates a massive collection of intramural gas (white arrows). Enteric contrast material defines the gastric lumen (*). Periportal edema is also seen (black arrows). (c) Photograph of the gross specimen reveals diffuse hemorrhagic necrosis (arrows) and thickened mucosal folds. A large number of gram-positive cocci were seen at histologic analysis.
|
|
View larger version (160K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7b. Emphysematous gastritis in a 33-year-old man with a history of ethanol abuse. (a) Abdominal radiograph obtained with the patient upright shows mottled and irregular collections of gas within the stomach wall (arrows). An endogastric tube and abdominal surgical clips are also seen. (b) Contrast-enhanced CT scan through the upper abdomen clearly demonstrates a massive collection of intramural gas (white arrows). Enteric contrast material defines the gastric lumen (*). Periportal edema is also seen (black arrows). (c) Photograph of the gross specimen reveals diffuse hemorrhagic necrosis (arrows) and thickened mucosal folds. A large number of gram-positive cocci were seen at histologic analysis.
|
|
View larger version (169K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7c. Emphysematous gastritis in a 33-year-old man with a history of ethanol abuse. (a) Abdominal radiograph obtained with the patient upright shows mottled and irregular collections of gas within the stomach wall (arrows). An endogastric tube and abdominal surgical clips are also seen. (b) Contrast-enhanced CT scan through the upper abdomen clearly demonstrates a massive collection of intramural gas (white arrows). Enteric contrast material defines the gastric lumen (*). Periportal edema is also seen (black arrows). (c) Photograph of the gross specimen reveals diffuse hemorrhagic necrosis (arrows) and thickened mucosal folds. A large number of gram-positive cocci were seen at histologic analysis.
|
|
View larger version (150K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8a. Emphysematous gastritis in a 69-year-old woman who presented with hypovolemia and metabolic acidosis. (a) Unenhanced CT scan through the upper abdomen shows nodular and irregular collections of gas within the stomach wall (black arrows). The presence of enteric contrast material aids in their visualization. Branching collections of gas extend peripherally within the liver (white arrows) in a pattern characteristic of portal venous air. (b) Photograph of the gross specimen shows a large area of necrosis involving the serosal surface of the posterior stomach wall (arrows). Large numbers of submucosal gas bubbles were present at the time of pathologic examination.
|
|
View larger version (99K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8b. Emphysematous gastritis in a 69-year-old woman who presented with hypovolemia and metabolic acidosis. (a) Unenhanced CT scan through the upper abdomen shows nodular and irregular collections of gas within the stomach wall (black arrows). The presence of enteric contrast material aids in their visualization. Branching collections of gas extend peripherally within the liver (white arrows) in a pattern characteristic of portal venous air. (b) Photograph of the gross specimen shows a large area of necrosis involving the serosal surface of the posterior stomach wall (arrows). Large numbers of submucosal gas bubbles were present at the time of pathologic examination.
|
|
An important differential diagnosis to consider is benign gastric emphysema. Gas collections form within the gastric wall without associated infection by gas-forming organisms (15). Gas may enter the wall from the lumen, peritoneal surface, or esophageal or duodenal connection and is usually associated with violent coughing, vomiting, or severe obstructive pulmonary disease. Gastric fold inflammation and thickening are not present, and the patient is usually asymptomatic with spontaneous resolution expected. The characteristic radiographic features of benign gastric emphysema include thin, linear streaks of air running parallel to the border of the stomach that do not change with patient position (Fig 9a) (15). CT will help confirm this linear distribution of mural air and, when performed with enteric contrast material, will demonstrate a normal gastric mucosal thickness of 3 mm or less (Fig 9b) (19,23). Other differential considerations for mottled midabdominal gas seen at radiography should include abscess involving the lesser sac or perinephric space, gastric bezoar, and emphysematous pancreatitis.
View larger version (163K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9a. Benign gastric emphysema in an asymptomatic 68-year-old man undergoing high-dose dexamethasone therapy. (a) Abdominal radiograph obtained with the patient upright demonstrates a thin, linear area of increased radiolucency that outlines the gastric wall (arrows). (b) Unenhanced CT scan obtained at the same level helps confirm the presence of a thin, linear distribution of intramural air (arrows). Compare this finding with the nodular appearance of emphysematous gastritis in Figure 8a.
|
|
View larger version (147K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9b. Benign gastric emphysema in an asymptomatic 68-year-old man undergoing high-dose dexamethasone therapy. (a) Abdominal radiograph obtained with the patient upright demonstrates a thin, linear area of increased radiolucency that outlines the gastric wall (arrows). (b) Unenhanced CT scan obtained at the same level helps confirm the presence of a thin, linear distribution of intramural air (arrows). Compare this finding with the nodular appearance of emphysematous gastritis in Figure 8a.
|
|
Treatment of emphysematous gastritis involves vigorous fluid support, correction of acid-base and electrolyte abnormalities, and coverage with intravenous broad-spectrum antimicrobial therapy. Unless perforation has occurred, surgery is best delayed until the fulminant sepsis can be better controlled. Even delayed surgeries have significant complications, including anastomotic breakdown, development of fistulas, and chronic stricture formation involving the distal esophagus and nonresected portions of the stomach (16,22, 24). The mortality rate of patients with emphysematous gastritis remains high (60%–80%) despite early aggressive treatment (15).
|
Emphysematous Pancreatitis
|
|---|
The most common causes of acute pancreatitis in North America are the passage of gallstones and alcohol abuse (25). An overall mortality rate of 4% rapidly escalates to more than 50% when complications (eg, abscess formation, superinfection with gas-forming bacteria) occur (26,27). The infecting organisms are usually coliform bacteria and may reach the pancreatic bed by way of the bloodstream or lymphatic channels, a fistula from adjacent bowel, transmural passage from the transverse colon, or reflux of enteric organisms into the pancreatic duct or biliary tree via a patulous ampulla of Vater (27–29). Gas may be detected in up to 22% of pancreatic abscesses; however, its presence alone is not specific for the diagnosis of infection (1,30). Other sources of intraductal or parenchymal pancreatic gas include reflux from the duodenum following sphincterotomy, endoscopic instrumentation, enteric fistula (commonly involving the transverse colon), and end-organ infarction (1). Patients with emphysematous pancreatitis are usually debilitated and often have underlying immunocompromised conditions such as poorly controlled diabetes or chronic renal failure.
Early radiographic detection of retroperitoneal gas is critical in the evaluation of superimposed emphysematous infection of the pancreas. Conventional abdominal radiography may demonstrate mottled gas overlying the midabdomen (Fig 10a). This finding is not specific for pancreatitis because abscess involving the lesser sac or perinephric space may also have this appearance. Diagnostic US is often of limited value in the evaluation of acute pancreatitis or its complications secondary to an adjacent air-filled small bowel loop from ileus. When identified, pancreatic gas will manifest as multiple irregular echogenic foci, often with posterior dirty acoustic shadowing. A significant volume of gas may limit the detection of adjacent fluid collections. CT is the modality of choice for detecting parenchymal gas as well as evaluating its extent and location (Fig 10b, Fig 10c). Fluid collections or portal venous air is readily identified, and, although intravenously administered contrast material is not necessary for the visualization of air, it is useful for evaluating potential complications including parenchymal necrosis and abscess formation (25,27,28).
View larger version (187K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10a. Emphysematous pancreatitis in a 68-year-old woman. (a) Digital scout image from a CT scan demonstrates a mottled collection of gas bubbles in the midportion of the upper abdomen and extending into the left upper quadrant. (b, c) Contrast-enhanced CT scans obtained at the same level as a show gas surrounding the body and tail of the pancreas (arrows in b) and extending more cephalad within the anterior pararenal space (c). There are extensive inflammatory changes involving the surrounding fat (arrows in c).
|
|
View larger version (183K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10b. Emphysematous pancreatitis in a 68-year-old woman. (a) Digital scout image from a CT scan demonstrates a mottled collection of gas bubbles in the midportion of the upper abdomen and extending into the left upper quadrant. (b, c) Contrast-enhanced CT scans obtained at the same level as a show gas surrounding the body and tail of the pancreas (arrows in b) and extending more cephalad within the anterior pararenal space (c). There are extensive inflammatory changes involving the surrounding fat (arrows in c).
|
|
View larger version (177K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10c. Emphysematous pancreatitis in a 68-year-old woman. (a) Digital scout image from a CT scan demonstrates a mottled collection of gas bubbles in the midportion of the upper abdomen and extending into the left upper quadrant. (b, c) Contrast-enhanced CT scans obtained at the same level as a show gas surrounding the body and tail of the pancreas (arrows in b) and extending more cephalad within the anterior pararenal space (c). There are extensive inflammatory changes involving the surrounding fat (arrows in c).
|
|
The prognosis for emphysematous pancreatitis is grave, and successful treatment requires aggressive management of the infection with systemic antimicrobial therapy and control of septic shock. Early surgical debridement or percutaneous drainage is usually performed, and recovery is typically prolonged (1).
|
Emphysematous Pyelonephritis
|
|---|
Emphysematous pyelonephritis represents a severe life-threatening infection of the renal parenchyma with gas-forming bacteria. Underlying poorly controlled diabetes mellitis is present in up to 90% of patients who develop emphysematous pyelonephritis. Urinary collecting system obstruction from pathologic conditions such as stone disease, urothelial neoplasm, or sloughed papilla (31) is also commonly present. Patients present clinically with varying degrees of renal failure, lethargy, acid-base irregularities, and hyperglycemia. Rapid progression to septic shock may be seen, and emphysematous pyelonephritis carries an overall mortality rate of approximately 50% (32). Flank pain and, rarely, crepitus over the lower back or thigh may be seen at physical examination (33). E coli is the causative bacterial source in approximately 70% of cases, with Klebsiella, Candida, and Pseudomonas species isolated less frequently (2). Conventional radiography may demonstrate gas bubbles overlying the renal fossa or may show a diffusely mottled kidney with radially oriented gas corresponding to the renal pyramids (Fig 11). The additional finding of a crescentic collection of gas within the Gerota fascia indicates extension into perirenal fat and a more advanced stage of renal necrosis (34). Intravenous urography will demonstrate a persistent nephrogram on the affected side secondary to delayed excretion of contrast material. The ipsilateral psoas shadow may be obscured and obstructing stones identified at abdominal radiography (Fig 12) (35). US will characteristically show an enlarged kidney containing high-amplitude echoes within the renal parenchyma, often with low-level posterior dirty acoustic shadowing (Figs 13a, 14a, 15b); however, the depth of parenchymal involvement may be underestimated at US, and multiple renal stones may also manifest as echogenic foci without "clean" posterior shadowing (36). Additional evaluation with CT will confirm the presence and extent of parenchymal gas (Figs 14b, 15c) and will often allow identification of the source of obstruction when present (Fig 12b). The use of intravenous contrast material will often reveal asymmetric renal enhancement or delayed excretion, and, during the nephrographic phase, will help identify areas of focal tissue necrosis or abscess formation. A CT classification scheme proposed by Wan et al (37) divides emphysematous pyelonephritis into two types and has prognostic significance. Type I emphysematous pyelonephritis is characterized by parenchymal destruction with streaky or mottled gas collections but no fluid collections (Fig 16a). Type II emphysematous pyelonephritis is characterized by bubbly or loculated gas within the parenchyma or collecting system with associated renal or perirenal fluid collections that are thought to represent a favorable immune response (Fig 16b). Type I emphysematous pyelonephritis has a 69% mortality rate versus 18% for type II, although transformation from type I to type II has been observed following conservative treatment (38). Nuclear scintigraphy is helpful in quantifying renal function prior to planned surgery. With minimal functional impairment and localized disease (discrete abscess or focal pyelonephritis), percutaneous drainage or partial nephrectomy may be at-tempted, whereas poor renal function would be an indication for total nephrectomy (2). Clinical indicators of poor prognosis include development of acute renal failure and thrombocytopenia (39).
View larger version (155K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 11. Bilateral emphysematous pyelonephritis in a 72-year-old man who presented with fever, chills, and near syncope. Abdominal radiograph reveals extensive, radially oriented air within and surrounding the kidneys (black arrows). Air is also seen within the left renal collecting system (white arrows).
|
|
View larger version (196K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12a. Emphysematous pyelonephritis in a 45-year-old woman. (a) Abdominal radiograph obtained with the patient upright demonstrates a 2-cm calcification overlying the region of the left ureteropelvic junction (arrow) and several smaller calcifications overlying the lower pole. Note also the mottled collection of gas bubbles in the region of the left lower renal pole (arrowheads) and the large air-fluid level within the upper pole (*). (b) Contrast-enhanced excretory-phase CT scan obtained at the same level as a demonstrates enlargement of the left kidney with persistent parenchymal enhancement relative to the normal right kidney. Note the air-fluid and debris level (*) within the upper pole, a finding that corresponds to the radiographic finding. A large obstructing ureteral stone (arrow) and perinephric inflammatory changes are also present. (c) Photograph of the cut gross specimen reveals diffuse parenchymal necrosis.
|
|
View larger version (158K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12b. Emphysematous pyelonephritis in a 45-year-old woman. (a) Abdominal radiograph obtained with the patient upright demonstrates a 2-cm calcification overlying the region of the left ureteropelvic junction (arrow) and several smaller calcifications overlying the lower pole. Note also the mottled collection of gas bubbles in the region of the left lower renal pole (arrowheads) and the large air-fluid level within the upper pole (*). (b) Contrast-enhanced excretory-phase CT scan obtained at the same level as a demonstrates enlargement of the left kidney with persistent parenchymal enhancement relative to the normal right kidney. Note the air-fluid and debris level (*) within the upper pole, a finding that corresponds to the radiographic finding. A large obstructing ureteral stone (arrow) and perinephric inflammatory changes are also present. (c) Photograph of the cut gross specimen reveals diffuse parenchymal necrosis.
|
|
View larger version (148K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 12c. Emphysematous pyelonephritis in a 45-year-old woman. (a) Abdominal radiograph obtained with the patient upright demonstrates a 2-cm calcification overlying the region of the left ureteropelvic junction (arrow) and several smaller calcifications overlying the lower pole. Note also the mottled collection of gas bubbles in the region of the left lower renal pole (arrowheads) and the large air-fluid level within the upper pole (*). (b) Contrast-enhanced excretory-phase CT scan obtained at the same level as a demonstrates enlargement of the left kidney with persistent parenchymal enhancement relative to the normal right kidney. Note the air-fluid and debris level (*) within the upper pole, a finding that corresponds to the radiographic finding. A large obstructing ureteral stone (arrow) and perinephric inflammatory changes are also present. (c) Photograph of the cut gross specimen reveals diffuse parenchymal necrosis.
|
|
View larger version (151K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13a. Emphysematous pyelonephritis in a 49-year-old diabetic woman. (a) Longitudinal US image of the left kidney demonstrates multiple hyperechoic foci (long arrows) with dirty acoustic shadowing (short arrow), a finding that represents gas within the renal parenchyma. (b) Photograph of the cut gross specimen reveals numerous parenchymal abscesses filled with yellow-tan purulent exudate (arrows).
|
|
View larger version (135K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 13b. Emphysematous pyelonephritis in a 49-year-old diabetic woman. (a) Longitudinal US image of the left kidney demonstrates multiple hyperechoic foci (long arrows) with dirty acoustic shadowing (short arrow), a finding that represents gas within the renal parenchyma. (b) Photograph of the cut gross specimen reveals numerous parenchymal abscesses filled with yellow-tan purulent exudate (arrows).
|
|
View larger version (150K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 14a. Emphysematous pyelonephritis. (a) Transverse US image through the middle of the left kidney shows high-amplitude echoes (long arrow) representing air along the nondependent aspect of a parenchymal fluid collection (*). The more posteriorly located perinephric air has a similar appearance (short arrows). (b) Contrast-enhanced CT scan (enteric contrast material) clearly depicts air within the kidney (*) and perinephric space (arrow).
|
|
View larger version (180K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 14b. Emphysematous pyelonephritis. (a) Transverse US image through the middle of the left kidney shows high-amplitude echoes (long arrow) representing air along the nondependent aspect of a parenchymal fluid collection (*). The more posteriorly located perinephric air has a similar appearance (short arrows). (b) Contrast-enhanced CT scan (enteric contrast material) clearly depicts air within the kidney (*) and perinephric space (arrow).
|
|
View larger version (161K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15a. Emphysematous pyelonephritis in a 60-year-old diabetic man with several days’ history of nausea and general malaise. (a) Longitudinal US image of the left kidney demonstrates normal findings. (b) Longitudinal US image of the right kidney shows foci of high-amplitude echoes (long arrow) with associated posterior dirty shadowing (short arrow). (c) Corresponding contrast-enhanced CT scan obtained during the late excretory phase shows multiple parenchymal gas collections (arrows). Earlier-phase images (not shown) demonstrated decreased perfusion and excretion relative to the normal left kidney.
|
|
View larger version (180K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15b. Emphysematous pyelonephritis in a 60-year-old diabetic man with several days’ history of nausea and general malaise. (a) Longitudinal US image of the left kidney demonstrates normal findings. (b) Longitudinal US image of the right kidney shows foci of high-amplitude echoes (long arrow) with associated posterior dirty shadowing (short arrow). (c) Corresponding contrast-enhanced CT scan obtained during the late excretory phase shows multiple parenchymal gas collections (arrows). Earlier-phase images (not shown) demonstrated decreased perfusion and excretion relative to the normal left kidney.
|
|
View larger version (172K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 15c. Emphysematous pyelonephritis in a 60-year-old diabetic man with several days’ history of nausea and general malaise. (a) Longitudinal US image of the left kidney demonstrates normal findings. (b) Longitudinal US image of the right kidney shows foci of high-amplitude echoes (long arrow) with associated posterior dirty shadowing (short arrow). (c) Corresponding contrast-enhanced CT scan obtained during the late excretory phase shows multiple parenchymal gas collections (arrows). Earlier-phase images (not shown) demonstrated decreased perfusion and excretion relative to the normal left kidney.
|
|
View larger version (164K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16a. Emphysematous pyelonephritis. (a) Type I emphysematous pyelonephritis. Contrast-enhanced CT scan demonstrates gas that radiates diffusely throughout the renal parenchyma (arrow). No associated fluid collections are seen. (b) Type II emphysematous pyelonephritis. CT scan obtained in a different patient shows several small foci of gas, some with associated regions of fluid attenuation (black arrows). These fluid-attenuation regions are thought to represent a more favorable immune response. Vicarious excretion of contrast material is also seen within the gallbladder (white arrow).
|
|
View larger version (161K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 16b. Emphysematous pyelonephritis. (a) Type I emphysematous pyelonephritis. Contrast-enhanced CT scan demonstrates gas that radiates diffusely throughout the renal parenchyma (arrow). No associated fluid collections are seen. (b) Type II emphysematous pyelonephritis. CT scan obtained in a different patient shows several small foci of gas, some with associated regions of fluid attenuation (black arrows). These fluid-attenuation regions are thought to represent a more favorable immune response. Vicarious excretion of contrast material is also seen within the gallbladder (white arrow).
|
|
First-line treatment for emphysematous pyelonephritis includes aggressive fluid support, correction of electrolyte and acid-base irregularities, hyperglycemic control, and intravenous broad-spectrum antimicrobial therapy. Hyperglycemic control in diabetic patients is easier following nephrectomy than with conservative therapy alone (33,38). Patients with a fulminant clinical course, unsuccessful drainage, or failed conservative therapy should undergo nephrectomy (31,32). In nondiabetic patients, successful removal of an obstruction, surgical or percutaneous drainage, and aggressive antimicrobial management may be sufficient (35,40).
|
Emphysematous Pyelitis
|
|---|
Emphysematous pyelitis is the term used to describe the presence of gas limited to the renal excretory system. Although the urothelium may be primarily involved, the gas is usually secondary to coexistent bacterial infections of the kidney or urinary bladder, with E coli being the most commonly cultured bacteria (41). Emphysematous pyelitis is seen more commonly in women, is often associated with underlying diabetes or obstructing stone disease, and carries a mortality rate of up to 20%, which is significantly lower than that of emphysematous pyelonephritis (2,33).
At conventional radiography, gas is seen filling and outlining the ureters and pelvicaliceal system (Fig 17). US typically shows high-amplitude shadowing along the nondependent surfaces with posterior dirty acoustic shadowing. CT best delineates gas within the collecting system and helps reliably identify ureteric stones. More importantly, CT helps exclude complicated forms of emphysematous pyelitis, such as the presence of renal or perirenal fluid collections, frank abscesses, or emphysematous pyelonephritis (Fig 18). Potential noninfectious sources of gas within the collecting system that should be excluded with patient history include reflux of air during instrumentation and the presence of an ilealureterosigmoidostomy (42).
View larger version (173K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 17a. Emphysematous pyelitis. (a) Abdominal radiograph obtained during the excretory phase of an intravenous urogram with the patient supine demonstrates multiple air bubbles within the renal collecting systems (arrows) and moderate hydronephrosis bilaterally. (b) Delayed tomographic image localized over the distal left ureter demonstrates multiple tiny intramural gas bubbles and a dilated left ureter (arrows).
|
|
View larger version (185K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 17b. Emphysematous pyelitis. (a) Abdominal radiograph obtained during the excretory phase of an intravenous urogram with the patient supine demonstrates multiple air bubbles within the renal collecting systems (arrows) and moderate hydronephrosis bilaterally. (b) Delayed tomographic image localized over the distal left ureter demonstrates multiple tiny intramural gas bubbles and a dilated left ureter (arrows).
|
|
View larger version (176K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 18. Complicated emphysematous pyelitis. Contrast-enhanced CT scan obtained at the level of the kidneys shows air within the left renal pelvis (white arrow) and anterior calix. Focal parenchymal (arrowheads) and perinephric (black arrows) fluid collections are also well demonstrated.
|
|
In the absence of obstruction, surgical or percutaneous drainage procedures are rarely needed, and emphysematous pyelitis will likely respond to intravenous antimicrobial therapy and careful attention to underlying comorbid conditions. The persistence of gas following conservative therapy indicates continued infection, which may then require more aggressive intervention.
|
Emphysematous Cystitis
|
|---|
Emphysematous cystitis represents a rare form of acute inflammation of the bladder mucosa and underlying musculature. Clinical symptoms of dysuria, increased urinary frequency, and hematuria are common. The presence of pneumaturia is a rare, although more specific, clinical finding. Underlying diabetes mellitus is present in over half of reported cases, with women being affected twice as often as men (35,43,44). Other predisposing conditions include chronic urinary tract infections, bladder outlet obstruction, and a neurogenic bladder (an increasingly common complication in elderly diabetic patients) (35,43). Frequently, isolated gas-producing bacteria include the coliform bacteria E coli and Enterobacter aerogens, although Clostridia and fungal species are occasionally identified. Possible noninfectious sources of pelvic air should be considered and include recent bladder instrumentation, vesicocolic or vesicovaginal fistulas, trauma, and pneumatosis cystoides intestinalis. Gas gangrene of the uterus and vaginitis emphysematosa may also overlie the pelvis, and further anatomic localization may be required (33,43). Conventional radiography of emphysematous cystitis characteristically shows curvilinear or mottled areas of increased radiolucency in the region of the urinary bladder, separate from more posterior rectal gas (Fig 19a). Intraluminal gas will be seen as an air-fluid level that changes with patient position, and, when adjacent to the nondependent mucosal surface, may have a cobblestone or "beaded necklace" appearance. This finding reflects the irregular thickening produced by submucosal blebs as seen at direct cystoscopy (35,43). US will commonly demonstrate diffuse bladder wall thickening and increased echogenicity. Focal regions of high-amplitude echoes with posterior dirty acoustic shadowing into the lumen may be seen in extensive cases (2,33). CT is a highly sensitive ex-amination that allows early detection of intraluminal or intramural gas (Figs 19b, 20) (45). It is also useful in evaluating other causes of intraluminal gas such as enteric fistula formation from adjacent bowel carcinoma or inflammatory disease. CT cystography has been shown to compare favorably with barium enema examination or cystoscopy in identifying a vesicocolic fistula (2,46). This procedure is easily performed by filling the urinary bladder to capacity in a retrograde manner via a Foley catheter with diluted water-soluble iodinated contrast material (2%–3% weight by volume) followed by contiguous axial imaging through the level of the bladder at 5–7-mm intervals.
View larger version (134K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 19a. Emphysematous cystitis. (a) Pelvic radiograph obtained with the patient upright demonstrates circumlinear streaks of increased radiolucency representing air in the expected location of the urinary bladder (arrows). (b) Contrast-enhanced CT scan obtained at the same level helps confirm the presence of multiple diffuse cystic collections of gas within the bladder wall (arrows). The bladder lumen is filled with contrast material (*).
|
|
View larger version (176K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 19b. Emphysematous cystitis. (a) Pelvic radiograph obtained with the patient upright demonstrates circumlinear streaks of increased radiolucency representing air in the expected location of the urinary bladder (arrows). (b) Contrast-enhanced CT scan obtained at the same level helps confirm the presence of multiple diffuse cystic collections of gas within the bladder wall (arrows). The bladder lumen is filled with contrast material (*).
|
|
View larger version (145K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 20a. Emphysematous cystitis in an 81-year-old diabetic man undergoing treatment for acute pancreatitis. (a) Contrast-enhanced arterial-phase CT scan through the pelvis shows a Foley catheter (arrowhead) and a rectal tube with a balloon cuff (thick arrow). There is a rounded collection of air within the urinary bladder (*) as well as multiple smaller locules of air more peripherally (thin arrows). (b) Delayed CT scan obtained at the same level shows contrast material within the bladder lumen (arrow). Both the large (*) and small collections of gas are clearly seen to be within the thickened anterior bladder wall rather than the bladder lumen.
|
|
View larger version (143K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 20b. Emphysematous cystitis in an 81-year-old diabetic man undergoing treatment for acute pancreatitis. (a) Contrast-enhanced arterial-phase CT scan through the pelvis shows a Foley catheter (arrowhead) and a rectal tube with a balloon cuff (thick arrow). There is a rounded collection of air within the urinary bladder (*) as well as multiple smaller locules of air more peripherally (thin arrows). (b) Delayed CT scan obtained at the same level shows contrast material within the bladder lumen (arrow). Both the large (*) and small collections of gas are clearly seen to be within the thickened anterior bladder wall rather than the bladder lumen.
|
|
Treatment for emphysematous cystitis involves broad-spectrum antimicrobial therapy, hyperglycemic control, and adequate urine drainage with correction of possible bladder outlet obstruction when present (33,43).
|
Gas Gangrene of the Uterus
|
|---|
Gas gangrene of the uterus is a rare entity that historically has been associated with primary uterine infection following septic abortion (2,47). Today, although uterine abscess may still occur during puerperium, the presence of air within the endometrium or myometrium more commonly indicates necrosis within an underlying neoplasm. Uterine leiomyoma, endometrial or cervical carcinoma, and colon carcinoma with fistula formation have been reported (2,47,48). The production of intrauterine gas is thought to occur secondary to bacterial metabolism of necrotic neoplastic tissues. Exotoxin-producing forms of Clostridia species are often isolated, although mixed infections with E coli or Streptococcus species are common (47).
The clinical manifestation of intrauterine infection is variable, ranging from mild urinary tract discomfort to fulminant sepsis. Pelvic radiography characteristically shows a localized, mottled collection of gas in the midline that is distinct from the surrounding bowel (Fig 21a). Contrast material within the colon or urinary bladder may help confirm the intrauterine location of the gas (Fig 21b). US will demonstrate an enlarged uterus with centrally increased echogenicity and may show free fluid within the pelvis. CT offers the most sensitive and specific evaluation by helping confirm the extent and location of gas (Fig 22). Further characterization of an underlying pelvic mass is best achieved with transvaginal US when the volume of gas is not large. Magnetic resonance imaging may also be beneficial. Potential noninfectious sources of intrauterine gas should be excluded and include recent instrumentation or sexual intercourse, benign fistulous tract with adjacent bowel, and pneumatometra with associated cervical stenosis (49). Vaginitis emphysematosa is an uncommon benign condition characterized by multiple gas-filled spaces within the submucosal lining of the upper vagina and ectocervix (Fig 23) (2). Trichomonas vaginalis is likely the causative microbe, and women with a depressed immune response (eg, during pregnancy or corticosteroid use) are at higher risk. The radiologic manifestation of vaginitis emphysematosa, best seen at CT, consists of multiple gas-filled cysts between 2 mm and 2 cm in size (50). Recognition of this entity is important because this condition does not represent an aggressive life-threatening infection, and spontaneous resolution is the rule (51).
View larger version (157K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 21a. Gas gangrene of the uterus in a 32-year-old postpartum patient. (a) Scout radiograph from an intravenous urogram demonstrates a large region of heterogeneously increased radiolucency centered within the pelvis representing mottled air (arrows). Discrimination between uterine and urinary bladder gas is difficult. (b) Delayed radiograph shows contrast material within the urinary collecting system and bladder that is clearly separate from the more posterior intrauterine gas.
|
|
View larger version (161K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 21b. Gas gangrene of the uterus in a 32-year-old postpartum patient. (a) Scout radiograph from an intravenous urogram demonstrates a large region of heterogeneously increased radiolucency centered within the pelvis representing mottled air (arrows). Discrimination between uterine and urinary bladder gas is difficult. (b) Delayed radiograph shows contrast material within the urinary collecting system and bladder that is clearly separate from the more posterior intrauterine gas.
|
|
View larger version (190K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 22a. Intrauterine gas. (a) Contrast-enhanced CT scan (enteric contrast material) through the pelvis obtained in a 27-year-old woman with fever who had recently given birth demonstrates a focal fluid collection with associated small gas collections within the anterior myometrium (black arrow). There is free fluid within the pelvis (white arrow). (b) Contrast-enhanced CT scan (enteric contrast material) through the pelvis obtained in a 36-year-old woman demonstrates a large soft-tissue mass (short arrows) containing multiple irregular gas collections (long arrows). The mass proved to be a large, infarcted uterine leiomyoma.
|
|
View larger version (179K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 22b. Intrauterine gas. (a) Contrast-enhanced CT scan (enteric contrast material) through the pelvis obtained in a 27-year-old woman with fever who had recently given birth demonstrates a focal fluid collection with associated small gas collections within the anterior myometrium (black arrow). There is free fluid within the pelvis (white arrow). (b) Contrast-enhanced CT scan (enteric contrast material) through the pelvis obtained in a 36-year-old woman demonstrates a large soft-tissue mass (short arrows) containing multiple irregular gas collections (long arrows). The mass proved to be a large, infarcted uterine leiomyoma.
|
|
Treatment for gas gangrene of the uterus depends on the extent of involvement. When the condition is confined to the endometrium, aggressive antimicrobial therapy and curettage may be sufficient. Once gas is identified within the myometrium (often at CT), curettage is of limited value and hysterectomy is required. Additional indications for hysterectomy include worsening acute renal failure and uncorrectable hemolysis, reflecting clinical deterioration due to fulminant sepsis. Prompt diagnosis and management reduces the mortality rate from 80% to less than 20% (47,52–54).
|
Fournier Gangrene
|
|---|
Although classically limited to involvement of the penis and scrotum, Fournier gangrene is an eponym now used to describe necrotizing fasciitis of the perineal, genital, or perianal regions. Men are affected 10 times more often than women, a wide age range has been reported, and the disease has a relatively high prevalence in North America. Predisposing factors reflect impaired host resistance from reduced cellular immunity. These factors include diabetes mellitus (seen in up to 60% of cases), alcoholism, and human immunodeficiency virus infection. The infection is most often polymicrobial, with Clostridia, Streptococci, and Staphylococci species and coliform bacteria commonly cultured. Bacterial sources originate from the adjacent skin, the rectum and anus, and the lower urinary tract. Synergistic effects of the bacteria lead to thrombosis of small subcutaneous vessels, and rapid gangrenous involvement of the surrounding skin and deep fascia ensues (55). Spread along the superficial perineal fascia (Colles fascia) may lead to involvement of the anterior abdominal wall. The attachment of the Colles fascia to the pubic rami and fascia lata laterally and to the urogenital diaphragm posteriorly helps limit spread into the posterolateral tissues and retroperitoneum. The Colles fascia extends anteriorly as the dartos fascia to envelop the scrotum and penis before continuing superiorly along the anterior abdominal wall as the Scarpa fascia. Perineal infection can readily spread along this fascial plane (56). The testicles are rarely involved in necrotizing fasciitis because they have a separate gonadal blood supply (57).
Clinical symptoms of Fournier gangrene often begin insidiously with perineal pruritis and swelling of the external genitalia. Initial bronzing of the skin will progress to erythema and, possibly, vesicle formation. When gas-forming organisms predominate, crepitus may be appreciated clinically (57,58). Diagnosis of Fournier disease is largely based on clinical examination, although radiography may help in cases of early manifestation or ambiguous physical findings. Radiography characteristically reveals marked swelling of the scrotal tissues and areas of hyperlucency representing interstitial air. Subcutaneous emphysema may extend laterally to the inguinal canal and superiorly to involve the abdominal wall. US will demonstrate highly echogenic subcutaneous gas (Fig 24) within an edematous scrotal wall with or without reactive extratesticular fluid (57,59,60). US is also helpful in excluding other causes of pneumoscrotum seen at radiography such as an incarcerated inguinoscrotal hernia (56). Although CT can help confirm Fournier gangrene, it is best used to evaluate the extent of disease, detect a potential underlying cause, and follow up therapeutic response. Findings of fat stranding and asymmetric fascial thickening correspond well to diseased tissue at surgical debridement, and deep pelvic or abdominal fluid collections are reliably detected with CT (61).
View larger version (167K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 24a. Fournier gangrene in a 66-year-old diabetic man with diffuse soft-tissue swelling and crepitus at physical examination. Longitudinal (a) and transverse (b) scrotal US images demonstrate high-amplitude echoes within the thickened scrotal tissues (arrows), a finding that corresponds to gas from necrotizing fasciitis. There is no involvement of the testicles (t).
|
|
View larger version (171K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 24b. Fournier gangrene in a 66-year-old diabetic man with diffuse soft-tissue swelling and crepitus at physical examination. Longitudinal (a) and transverse (b) scrotal US images demonstrate high-amplitude echoes within the thickened scrotal tissues (arrows), a finding that corresponds to gas from necrotizing fasciitis. There is no involvement of the testicles (t).
|
|
Treatment for Fournier gangrene must rapidly address the underlying sepsis. Aggressive fluid resuscitation, empiric broad-spectrum antimicrobial therapy, and early surgical intervention are essential to prevent or lessen the severity of septic shock and multiorgan failure. Multiple surgical debridements of the affected area are often necessary to remove all nonviable tissue and help alleviate the nidus of systemic toxicity. Adjuvant hyperbaric oxygen therapy has been shown to be beneficial in some studies, but its role as a primary treatment modality remains controversial (62–64). The overall mortality rate for patients with Fournier gangrene is 21%, with rapid escalation to over 70% if the disease is not aggressively addressed within the first several days (57,65).
|
Conclusions
|
|---|
Gas-forming infections within the abdomen and pelvis are potentially life-threatening conditions. The initial clinical manifestation may be insidious, but rapid progression to sepsis will occur in the absence of early therapeutic intervention. Conventional radiography and US are often the initial imaging modalities used to evaluate patients with abdominopelvic complaints. These modalities should be considered complementary, each with strengths and limitations as discussed in this article. When a differential diagnosis remains, or if further localization or confirmation is needed, CT should be considered the imaging modality of choice. CT is both highly sensitive and specific in the detection of abnormal gas and well suited to reliable depiction of the anatomic location and extent of the gas.
Therefore, with regard to emphysematous infections, appropriate radiologic evaluation combined with accurate interpretation of findings will help ensure rapid diagnosis and optimal treatment planning. Of equal importance may be the ability to reliably identify benign sources of gas, because treatment (if any) varies dramatically depending on the source. In addition, knowledge of the pathophysiologic characteristics and common predisposing conditions associated with gas-forming infections of the gallbladder, stomach, pancreas, and genitourinary system will aid in further diagnostic work-up, surveillance of potential complications, and evaluation of therapeutic response.
|
Footnotes
|
|---|
The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as representing the views of the Departments of the Army, Air Force, or Defense.
|
References
|
|---|
-
Daly JJ, Jr, Alderman DF, Conway WF. General case of the day. RadioGraphics 1995; 15:489-492.[Medline]
-
Joseph RC, Amendola MA, Artze ME, et al. Genitourinary tract gas: imaging evaluation. RadioGraphics 1996; 16:295-308.[Abstract]
-
Jolly BT, Love JN. Emphysematous cholecystitis in an elderly woman: case report and review of the literature. J Emerg Med 1993; 11:593-597.[CrossRef][Medline]
-
Hegner CF. Gaseous pericholecystitis with cholecystitis and cholelithiasis. Arch Surg 1931; 22:993-1000.[Abstract/Free Full Text]
-
Mentzer RM, Jr, Golden GT, Chandler JG, Horsley JS. A comparative appraisal of emphysematous cholecystitis. Am J Surg 1975; 129:10-15.[CrossRef][Medline]
-
May RE, Strong R. Acute emphysematous cholecystitis. Br J Surg 1971; 58:453-458.[Medline]
-
Tellez LG, Rodriguez-Montes JA, de Lis SF, Martin LG. Acute emphysematous cholecystitis: report of twenty cases. Hepatogastroenterology 1999; 46:2144-2148.[Medline]
-
Gill KS, Chapman AH, Weston MJ. The changing face of emphysematous cholecystitis. Br J Radiol 1997; 70:986-991.[Abstract]
-
Wu CS, Yao WJ, Hsiao CH. Effervescent gallbladder: sonographic findings in emphysematous cholecystitis. J Clin Ultrasound 1998; 26:272-275.[CrossRef][Medline]
-
Nemcek AA, Jr, Gore RM, Vogelzang RL, Grant M. The effervescent gallbladder: a sonographic sign of emphysematous cholecystitis. AJR Am J Roentgenol 1988; 150:575-577.[Free Full Text]
-
McMillin K. Computed tomography of emphysematous cholecystitis. J Comput Assist Tomogr 1985; 9:330-332.[Medline]
-
Morrison JC, Ramos-Gabatin A, Gelormini RG, Brown JW, Pitts NL. Prompt visualization of the gallbladder with a rim sign: acute or subacute cholecystitis? J Nucl Med 1993; 34:1169-1171.[Abstract/Free Full Text]
-
Meekin GK, Ziessman HA, Klappenbach RS. Prognostic value and pathophysiologic significance of the rim sign in cholescintigraphy. J Nucl Med 1987; 28:1679-1682.[Abstract/Free Full Text]
-
Vingan HL, Wohlgemuth SD, Bell JS, III. Percutaneous cholecystostomy drainage for the treatment of acute emphysematous cholecystitis. AJR Am J Roentgenol 1990; 155:1013-1014.[Free Full Text]
-
Kussin SZ, Henry C, Navarro C, Stenson W, Clain DJ. Gas within the wall of the stomach: report of a case and review of the literature. Dig Dis Sci 1982; 27:949-954.[CrossRef][Medline]
-
Meyers HI, Parker JJ. Emphysematous gastritis. Radiology 1967; 89:426-431.[Medline]
-
Fraenkel E. Ueber einen fall von gastritis acuta emphysematosa, wahrscheinlich mykotischen ursprunges. Virchows Arch Path Anat 1889; 118:526-535.[CrossRef]
-
Weens HS. Emphysematous gastritis. AJR Am J Roentgenol 1946; 55:588-593.
-
Moosvi AR, Saravolatz LD, Wong DH, Simms SM. Emphysematous gastritis: case report and review. Rev Infect Dis 1990; 12:848-855.[Medline]
-
Bashour CA, Popovich MJ, Irefin SA, Esfandiari S. Emphysematous gastritis. Surgery 1998; 123:716-718.[Medline]
-
Binmoeller KF, Benner KG. Emphysematous gastritis secondary to gastric infarction. Am J Gastroenterol 1992; 87:526-529.[Medline]
-
Van Allen RJ, Krebs TL, Henzie GM, Fermelia DE. Emphysematous gastritis in an immunocompromised host. Clin Imaging 1995; 19:129-130.[CrossRef][Medline]
-
Fishman EK, Urban BA, Hruban RH. CT of the stomach: spectrum of disease. RadioGraphics 1996; 16:1035-1054.[Abstract]
-
de Lange EE, Slutsky VS, Swanson S, Shaffer HA, Jr. Computed tomography of emphysematous gastritis. J Comput Assist Tomogr 1986; 10:139-141.[Medline]
-
Balthazar EJ. CT diagnosis and staging of acute pancreatitis. Radiol Clin North Am 1989; 27:19-37.[Medline]
-
Federle MP, Jeffrey RB, Crass RA, Van Dalsem V. Computed tomography of pancreatic abscesses. AJR Am J Roentgenol 1981; 136:879-882.[Abstract/Free Full Text]
-
Mendez G, Jr, Isikoff MB. Significance of intrapancreatic gas demonstrated by CT: a review of nine cases. AJR Am J Roentgenol 1979; 132:59-62.[Abstract]
-
Torres WE, Clements JL, Jr, Sones PJ, Knopf DR. Gas in the pancreatic bed without abscess. AJR Am J Roentgenol 1981; 137:1131-1133.[Abstract/Free Full Text]
-
Itai J, Ohtomi K, Nagai H, Itomi Y, Kuroda A. CT demonstration of gas in dilated pancreatic duct. J Comput Assist Tomogr 1986; 10:1052-1053.[Medline]
-
Balthazar EJ, Ranson JHC, Naidich DP, et al. Acute pancreatitis: prognostic value of CT. Radiology 1985; 156:767-772.[Abstract/Free Full Text]
-
Huang JJ, Tseng CC. Emphysematous pyelonephritis: clinicoradiological classification, management, prognosis, and pathogenesis. Arch Intern Med 2000; 160:797-805.[Abstract/Free Full Text]
-
Chen MT, Huang CN, Chou YH, Huang CH, Chiang CP, Liu GC. Percutaneous drainage in the treatment of emphysematous pyelonephritis: 10-year experience. J Urol 1997; 157:1569-1573.[CrossRef][Medline]
-
Patterson JE, Andriole VT. Bacterial urinary tract infections in diabetes. Infect Dis Clin North Am 1997; 11:735-747.[CrossRef][Medline]
-
Langston CS, Pfister RC. Renal emphysema. AJR Am J Roentgenol 1970; 110:778-786.[Abstract]
-
Patel NP, Lavengood RW, Fernandes M, Ward JN, Walzak MP. Gas-forming infections in the genitourinary tract. Urology 1992; 39:341-345.[CrossRef][Medline]
-
Best CD, Terris MK, Tacker JR, Reese JH. Clinical and radiological findings in patients with gas forming renal abscess treated conservatively. J Urol 1999; 162:1273-1276.[CrossRef][Medline]
-
Wan YL, Lee TY, Bullard MJ, Tsai CC. Acute gas-producing bacterial renal infection: correlation between imaging findings and clinical outcome. Radiology 1996; 198:433-438.[Abstract/Free Full Text]
-
Komura S, Shindoh N, Minowa O, Ozaki Y, Kyogoku S, Sumi Y. Emphysematous pyelonephritis: conversion of type I to type II appearance on serial CT studies. Clin Imaging 1999; 23:386-388.[CrossRef][Medline]
-
Wan YL, Lo SK, Bullard MJ, Chang PL, Lee TZ. Predictors of outcome in emphysematous pyelonephritis. J Urol 1998; 159:369-373.[CrossRef][Medline]
-
Roberts JA. Management of pyelonephritis and upper urinary tract infections. Urol Clin North Am 1999; 26:753-763.[CrossRef][Medline]
-
Bos CJ. Cystitis emphysematosa. Radiol Clin Biol 1972; 41:499-503.[Medline]
-
Roy C, Pfleger DD, Tuchmann CM, Lang HH, Saussine CC, Jacqmin D. Emphysematous pyelitis: findings in five patients. Radiology 2001; 218:647-650.[Abstract/Free Full Text]
-
Quint HJ, Rappaport WD, Hoffmann CJ. Emphysematous cystitis: a review of the spectrum of disease. J Urol 1992; 147:134-137.[Medline]
-
Kauzlaric D, Barmeir E. Sonography of emphysematous cystitis. J Ultrasound Med 1985; 4:319-320.[Medline]
-
Bohlman ME, Fishman EK, Oesterling JE, Goldman SM. Case profile: CT findings in emphysematous cystitis. Urology 1988; 32:63-64.[CrossRef][Medline]
-
Jarret TW, Vaughan ED, Jr. Accuracy of computerized tomography in the diagnosis of colovesical fistula secondary to diverticular disease. J Urol 1995; 153:44-46.[CrossRef][Medline]
-
Dylewski J, Wiesenfeld H, Latour A. Postpartum uterine infection with clostridium perfringens. Rev Infect Dis 1989; 11:470-473.[Medline]
-
Gross BH, Jafri SZ, Glazer GM. Significance of intrauterine gas demonstrated by computed tomography. J Comput Assist Tomogr 1983; 7:842-845.[Medline]
-
Muram D, Winer-Muram HT, Gale C. Pneumatometra. Am J Obstet Gynecol 1990; 162:1282- 1283.[Medline]
-
Francke P, Jr. Vaginitis emphysematosa. Radiology 1961; 77:114-116.
-
Leder RA, Paulson EK. Vaginitis emphysematosa: CT and review of the literature. AJR Am J Roentgenol 2001; 176:623-625.[Abstract/Free Full Text]
-
Braverman J, Adachi A, Lev-Gur M, et al. Spontaneous clostridia gas gangrene of uterus associated with endometrial malignancy. Am J Obstet Gynecol 1987; 156:1205-1207.[Medline]
-
Decker WH, Hall W. Treatment of abortions infected with clostridium welchii. Am J Obstet Gynecol 1966; 95:394-399.[Medline]
-
Pritchard JA, Whalley PJ. Abortion complicated by Clostridium perfringens infection. Am J Obstet Gynecol 1971; 111:484-492.[Medline]
-
Vick R, Carson CC, III. Fournier’s disease. Urol Clin North Am 1999; 26:841-849.[CrossRef][Medline]
-
Yaghan RJ, Al-Jaberi TM, Bani-Hani I. Fournier’s gangrene: changing face of the disease. Dis Colon Rectum 2000; 43:1300-1308.[CrossRef][Medline]
-
Rajan DK, Scharer KA. Radiology of Fournier’s gangrene. AJR Am J Roentgenol 1998; 170:163-168.[Free Full Text]
-
Eke N. Fournier’s gangrene: a review of 1726 cases. Br J Surg 2000; 87:718-728.[CrossRef][Medline]
-
Grant RW, Mitchell-Heggs P. Radiological features of Fournier’s gangrene. Radiology 1981; 140:641-643.[Abstract/Free Full Text]
-
Steiner RM, Mediano WM, Weissman G, Wolgin W. The radiology of Fournier’s gangrene. Br J Radiol 1977; 50:437-438.[CrossRef][Medline]
-
Wysoki MG, Santora TA, Shah RM, Friedman AC. Necrotizing fasciitis: CT characteristics. Radiology 1997; 203:859-863.[Abstract/Free Full Text]
-
Hollabaugh RS, Jr, Domochowski RR, Hickerson WL, Cox CE. Fournier’s gangrene: therapeutic impact of hyperbaric oxygen. Plast Reconstr Surg 1998; 101:94-100.[Medline]
-
Riseman JA, Zamboni WA, Curtis A, Graham DR, Konrad HR, Ross DS. Hyperbaric oxygen therapy for necrotizing fasciitis reduces mortality and the need for debridement. Surgery 1990; 108:847-850.[Medline]
-
Korhonen K, Hirn M, Niinikoski J. Hyperbaric oxygen in the treatment of Fournier’s gangrene. Eur J Surg 1998; 164:251-255.[CrossRef][Medline]
-
Stamenkovic I, Lew PD. Early recognition of potentially fatal necrotizing fasciitis: the use of frozen-section biopsy. N Engl J Med 1984; 310:1689-1693.[Abstract]
This article has been cited by other articles:
|
|
|
|
 
S.-H. Tsai and S.-J. Chu
Outlined psoas muscle shadow
BMJ Case Reports,
January 8, 2009;
2009(jan08_1):
bcr2006041970 - bcr2006041970.
[Full Text]
|
|
|
|
|
|
|
P. Leclercq MD, M. Hanssen MD, P. Borgoens MD, P.-J. Bruyere MD, and P. Lancellotti MD PhD
Emphysematous cystitis
Can. Med. Assoc. J.,
March 25, 2008;
178(7):
836 - 836.
[Full Text]
[PDF]
|
|
|
|
|
|
|
R. B. Levenson, A. K. Singh, and R. A. Novelline
Fournier Gangrene: Role of Imaging
RadioGraphics,
March 1, 2008;
28(2):
519 - 528.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
W. D. Craig, B. J. Wagner, and M. D. Travis
From the Archives of the AFIP: Pyelonephritis: Radiologic-Pathologic Review
RadioGraphics,
January 1, 2008;
28(1):
255 - 276.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
S.-H. Tsai and S.-J. Chu
Outlined psoas muscle shadow
Emerg. Med. J.,
October 1, 2007;
24(10):
738 - 738.
[Full Text]
[PDF]
|
|
|
|
|
|
|
Y. Watanabe, M. Nagayama, A. Okumura, Y. Amoh, T. Katsube, T. Suga, S. Koyama, K. Nakatani, and Y. Dodo
MR Imaging of Acute Biliary Disorders
RadioGraphics,
March 1, 2007;
27(2):
477 - 495.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
D. Grand, K. M. Horton, and E. Fishman
CT of the Gallbladder: Spectrum of Disease
Am. J. Roentgenol.,
July 1, 2004;
183(1):
163 - 170.
[Full Text]
[PDF]
|
|
|
|
|
|
|
A. E. Hanbidge, P. M. Buckler, M. E. O'Malley, and S. R. Wilson
From the RSNA Refresher Courses: Imaging Evaluation for Acute Pain in the Right Upper Quadrant
RadioGraphics,
July 1, 2004;
24(4):
1117 - 1135.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
K. K. L. Choong
Sonographic Detection of Emphysematous Cystitis
J. Ultrasound Med.,
August 1, 2003;
22(8):
847 - 849.
[Full Text]
[PDF]
|
|
|
Top
Abstract
LEARNING OBJECTIVES
