DOI: 10.1148/rg.254045035
RadioGraphics 2005;25:997-1015
© RSNA, 2005
CT of Internal Hernias1
Nobuyuki Takeyama, MD,
Takehiko Gokan, MD,
Yoshimitsu Ohgiya, MD,
Shuichi Satoh, MD,
Takashi Hashizume, MD,
Kiyoshi Hataya, MD,
Hiroshi Kushiro, MD,
Makoto Nakanishi, MD,
Mitsuo Kusano, MD and
Hirotsugu Munechika, MD
1 From the Departments of Radiology (N.T., T.G., Y.O., T.H., H.M.) and General and Gastrointestinal Surgery (M.K.), Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8666, Japan; the Departments of Radiology (S.S.) and Surgery (K.H.), Yokohama Asahi Chuo General Hospital, Yokohama, Japan; the Department of Surgery, Kikuna Memorial Hospital, Yokohama, Japan (H.K.); and the Department of Surgery, Totsuka Kyouritsu Hospital, Yokohama, Japan (M.N.). Recipient of a Certificate of Merit award for an education exhibit at the 2003 RSNA Annual Meeting. Received March 12, 2004; revision requested April 8; final revision received September 30; accepted October 5. All authors have no financial relationships to disclose.
Address correspondence to N.T. (e-mail: momiji{at}mtc.biglobe.ne.jp).
 |
Abstract
|
|---|
Computed tomography (CT) plays an important role in diagnosis of acute intestinal obstruction and planning of surgical treatment. Although internal hernias are uncommon, they may be included in the differential diagnosis in cases of intestinal obstruction, especially in the absence of a history of abdominal surgery or trauma. CT findings of internal hernias include evidence of small bowel obstruction (SBO); the most common manifestation of internal hernias is strangulating SBO, which occurs after closed-loop obstruction. Therefore, in patients suspected to have internal hernias, early surgical intervention may be indicated to reduce the high morbidity and mortality rates. In a study of 13 cases of internal hernias, nine different types of internal hernias were found and the surgical and radiologic findings were correlated. The following factors may be helpful in preoperative diagnosis of internal hernias with CT: (a) knowledge of the normal anatomy of the peritoneal cavity and the characteristic anatomic location of each type of internal hernia; (b) observation of a saclike mass or cluster of dilated small bowel loops at an abnormal anatomic location in the presence of SBO; and (c) observation of an engorged, stretched, and displaced mesenteric vascular pedicle and of converging vessels at the hernial orifice.
© RSNA, 2005
|
LEARNING OBJECTIVES FOR TEST 4
|
|---|
After reading this article and taking the test, the reader will be able to:
- Describe the normal anatomy of the peritoneal cavity and the characteristic anatomic location of each type of internal hernia.
- Identify the characteristic CT appearances of various types of internal hernias.
- Discuss the clinical findings and appropriate management of internal hernias.
|
Introduction
|
|---|
Internal hernias involve protrusion of the viscera through the peritoneum or mesentery and into a compartment in the abdominal cavity. The most common presentation is an acute intestinal obstruction of small bowel loops that develops through normal or abnormal apertures (1,2). The responsible hernial orifices are usually preexisting anatomic structures, such as foramina, recesses, and fossae. Pathologic defects of the mesentery and visceral peritoneum, which are caused by congenital mechanisms, surgery, trauma, inflammation, and circulation, are also potential herniation orifices (3,4).
Preoperative diagnosis is difficult because clinical symptoms may range from intermittent and mild digestive complaints to acute-onset intestinal obstruction. Internal hernias are silent if they are easily reducible, but the majority often cause epigastric discomfort, periumbilical pain, and recurrent episodes of intestinal obstruction (3,5). Internal hernias are clinically apparent only when incarcerated internal hernias result from small bowel obstruction (SBO); therefore, a delay in diagnosis may lead to strangulation and an increased risk of serious complications.
We categorized various internal hernias and potential orifices with relative frequency (Table) on the basis of their topographic distribution in the peritoneal cavity (Figs 1, 2) according to the classification of Welch (8).
View larger version (167K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1. Drawing (coronal view) shows the locations and directions of internal hernias of the upper and lower abdominal peritoneal cavity. A = foramen of Winslow hernia, B = left paraduodenal hernia, C = right paraduodenal hernia, D = transmesenteric hernia, E = pericecal hernia, F = transomental hernia, G = intersigmoid hernia. (Adapted and reprinted, with permission, from reference 6.)
|
|
View larger version (103K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2. Drawing (superior view) shows the locations of internal hernias, pouches, and fossae of the pelvic cavity in a female patient. H = supravesical hernia, I = hernia through the broad ligament, 1 = vesicouterine pouch, 2 = Douglas (rectouterine) pouch, 3 = perirectal fossa. (Adapted and reprinted, with permission, from reference 7.)
|
|
In this article, we describe our clinical experience with internal hernias, the imaging technique, and diagnosis with computed tomography (CT), including the CT findings and their clinical relevance as well as the important role of multi–detector row CT. We then discuss the locations and relative frequencies of internal hernias, which include foramen of Winslow, paraduodenal, transmesenteric, transomental, pericecal, sigmoid mesocolon, and supravesical and pelvic hernias.
In the sections on internal hernias, we describe the anatomic locations and embryologic features of potential hernial orifices (foramina, fossae, recesses, defects of the mesentery and visceral peritoneum) and the clinical, surgical, and radiologic findings, including the characteristic CT appearances. We also present CT images, some surgical results, and some intraoperative photographs. Finally, we briefly describe the management of internal hernias.
|
Clinical Experience
|
|---|
From November 1995 to February 2004, a retrospective review of medical records and radiologic images revealed 13 patients (eight male, five female) with surgically proved internal hernias at our institution and branch hospitals. Their age ranged from 12 to 86 years (mean age, 56.1 years) with more than half of the patients over age 50 years. All patients except one with clinical and radiologic findings suggestive of acute intestinal obstruction underwent single detector row CT of the abdomen and pelvis at the time of admission. One patient underwent CT 4 days after conservative treatment. Four patients with low-grade obstruction underwent enteroclysis, which is particularly helpful in depicting and grading the severity of partial obstruction and demonstrating sites of incomplete obstruction.
CT examinations were performed with the following imaging units: ProSeed SA (GE Healthcare Technologies, Waukesha, Wis) (n = 7); Hi-speed DXI (GE Healthcare Technologies) (n = 1); TCT-700S (Toshiba, Tokyo, Japan) (n = 1); TCT-60A (Toshiba) (n = 2); and SCT-7000 (Shimadzu, Kyoto, Japan) (n = 2).
The duration of symptoms before hospital admission ranged from as little as 3 hours to as long as 3 months. The interval between CT examination at the time of admission and surgery ranged from 2 hours to 20 days. Six patients underwent emergency operations within 7 hours of CT examination. Four patients were treated conservatively with insertion of a nasogastric tube or a long intestinal tube to drain the intestinal fluid, but these patients underwent operations within 12–42 hours of CT examination because of aggravated symptoms. The remaining three patients underwent operations within 4–20 days after CT examinations because at first they were making good progress with conservative treatment by means of nasogastric or long intestinal tube decompression, but their symptoms became aggravated little by little.
During laparotomy in each patient, reduction of the hernia contents, resection of necrotic bowel loops, and primary anastomosis (enterostomy in one case) were performed. Gangrenous changes in the incarcerated bowel loops were present in seven patients, and six patients had viable bowel loops. Eleven patients had no history of abdominal surgery or trauma. Only two patients had a history of appendectomy.
Nonspecific abdominal symptoms of intestinal obstruction were observed in all 13 patients. These included some degree of epigastric pain, abdominal pain, tenderness, abnormal bowel sounds, nausea, vomiting, and palpation of a mass.
|
Imaging Technique
|
|---|
Gastrointestinal studies enhanced with intraluminal contrast material (barium-enhanced studies, enteroclysis) and abdominal CT enable accurate diagnosis of any type of internal hernia (9,10). In mechanical high-grade SBO, small bowel follow-through study has a limitation in emergency use. Enteroclysis can be performed more quickly and has been shown to have high accuracy in the evaluation of SBO, but is contraindicated in patients with high-grade closed-loop obstruction and in those with suspected hernial strangulation (11). Recently, CT has demonstrated the importance of preoperative diagnosis of early or partial obstruction and closed-loop obstruction.
In our CT examination, intravenous administration of contrast material is essential to determine the cause of obstruction and identify any associated hernial strangulation. All patients except one underwent CT performed with 100 mL of contrast material administered intravenously at a rate of 1–2 mL/sec. The delay between the start of injection and imaging varied between 70 and 90 seconds. All images were acquired with 7–10-mm collimation and a pitch of 1.2–1.5. One patient underwent nonenhanced CT because she was allergic to the contrast material; CT images clearly demonstrated the presence of strangulating bowel loops as diffuse mesenteric fluid and haziness.
Because of the difficulty of preoperative CT diagnosis, multi–detector row CT may play an important role. Currently, multi–detector row technology provides substantial improvements in the quality of two- and three-dimensional reformatted images, which have evolved in addition to the axial images. Many images obtained with multi–detector row CT are interpreted at workstations by manually paging up and down or reformatting by means of high-quality three-dimensional reformation techniques, such as multiplanar reformation (MPR), shaded surface display (SSD), volume rendering (VR), and maximum intensity projection (MIP).
Multi–detector row CT with three-dimensional reformatting at a workstation provides important advantages over conventional imaging methods in evaluation of the small intestine and surrounding structures (mesentery, mesenteric vasculature, and peritoneal cavity). Multi–detector row CT can play a more active role in identification of the site, level, and cause of SBO, including internal hernias (12,13).
Oral administration of contrast material and water is not necessary in view of the patients’ severe condition because intraluminal fluid collected within an SBO segment already serves as a natural contrast agent, demonstrating the bowel wall clearly (12,13). On the other hand, multi–detector row CT coupled with administration of water and oral contrast material allows the diagnosis of SBO. Some investigators advocate use of CT enteroclysis, which provides a flexible method of viewing SBO (14).
|
Diagnosis of Internal Hernias with CT
|
|---|
Because clinical diagnosis of internal hernias is difficult, imaging studies may play an important role if accurate and reliable CT findings can be obtained. However, CT evaluation of any type of internal hernia is rare in the radiology literature, except for a few reports on paraduodenal and transmesenteric hernias.
The most common internal hernia is strangulating SBO, which occurs after a closed-loop obstruction. CT findings of internal hernias include evidence of SBO. To diagnose the hernial strangulation, many researchers stress the importance of observing the configuration of the obstructed loop, mesenteric changes, and the enhancement patterns of the bowel wall (15–19). In this article, we evaluate two characteristic CT findings: bowel configuration and mesenteric changes. The former consists of a saclike mass or cluster of dilated bowel loops. The latter consists of a mesenteric vascular pedicle that is engorged, stretched, and displaced; in addition, the dilated bowel loops have converging vessels at the entrance of the hernial orifice, thus revealing the impaired venous drainage and continuous influx of the arterial flow (1,3,9,10,15–19).
|
Locations and Relative Frequencies of Internal Hernias
|
|---|
The occurrence of abdominal internal hernias is rare. They are reported in 0.2%–0.9% of autopsies (2) and in 0.5%–4.1% of cases of intestinal obstruction (3,8,20). The locations and relative frequencies of internal hernias are as follows: paraduodenal, 53%; pericecal, 13%; foramen of Winslow, 8%; transmesenteric and transmesocolic, 8%; pelvic and supravesical, 6%; sigmoid mesocolon, 6%; and transomental, 1%–4% (1–3,20,21).
|
Foramen of Winslow Hernia
|
|---|
Anatomy
The lesser sac and the greater peritoneal cavity communicate through the epiploic foramen of Winslow. This potential opening is a 3-cm vertical slit situated beneath the upper part of the right border of the lesser sac, cephalad to the duodenal bulb and deep to the liver (Fig 1, A). This foramen is located anterior to the inferior vena cava and posterior to the hepatoduodenal ligament, including the portal vein, common bile duct, and hepatic artery (1–3,22).
Features
Foramen of Winslow hernias make up 8% of all internal hernias (1–3). The intestinal segment most commonly involved is the small intestine (60%–70%). The terminal ileum, cecum, and ascending colon are involved at a rate of about 25%–30% (1,2). Hernias involving the transverse colon, omentum, and gallbladder are rare, although some have been reported in the literature. Predisposing factors include an enlarged foramen of Winslow and excessively mobile intestinal loops due to a long mesentery or persistence of the ascending mesocolon and an ascending colon that is not fused to the parietal peritoneum (1–4,23–26).
Characteristic plain radiographic findings are gas-containing intestinal loops high in the abdomen and medial and posterior to the stomach associated with SBO (Fig 3). The cecum and ascending colon may be absent from their usual locations if they are part of the herniated viscera. Barium-enhanced radiography of the small intestine shows dilatation of bowel loops and usually reveals the obstruction at the right upper abdomen. Narrowing or obstruction at the hepatic flexure may be visualized with barium enema examination if the hernia involves the cecum and ascending colon (23). The following are the characteristic CT appearances: (a) presence of mesentery between the inferior vena cava and main portal vein, (b) an air-fluid collection in the lesser sac with a beak directed toward the foramen of Winslow, (c) absence of the ascending colon in the right gutter, and (d) two or more bowel loops in the high subhepatic spaces (1–3,24–26).
View larger version (143K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3a. Foramen of Winslow hernia in a 45-year-old man with acute epigastric pain of 18 hours duration. (a) Abdominal radiograph shows gas-containing small bowel loops (arrows) in the center of the upper abdomen between the liver and the gastric air bubble. (b) Image obtained with enteroclysis performed through a long intestinal tube shows an SBO at the right hepatic flexure (arrow). (c) Contrast-enhanced CT scan of the upper abdomen shows the cluster of dilated small bowel loops (arrowheads) in the lesser sac. There are stretched and converging mesenteric vessels (arrow) between the portal vein in the hepatoduodenal ligament (H) and the inferior vena cava (I). (d) CT scan obtained at the level of the pancreatic head shows crowded mesenteric vessels from the superior mesenteric vein (arrow) between the ascending portion of the duodenum (D) and the pancreatic head (P). Arrowheads = small bowel loops. At laparotomy performed 31 hours after CT, adhesion between the gastrocolic ligament and the transverse mesocolon was found. Approximately 50 cm of ileum, located 200 cm from the ligament of Treitz, was herniated into the lesser sac. The herniated ileal loops demonstrated only congestive changes without gangrene.
|
|
View larger version (162K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3b. Foramen of Winslow hernia in a 45-year-old man with acute epigastric pain of 18 hours duration. (a) Abdominal radiograph shows gas-containing small bowel loops (arrows) in the center of the upper abdomen between the liver and the gastric air bubble. (b) Image obtained with enteroclysis performed through a long intestinal tube shows an SBO at the right hepatic flexure (arrow). (c) Contrast-enhanced CT scan of the upper abdomen shows the cluster of dilated small bowel loops (arrowheads) in the lesser sac. There are stretched and converging mesenteric vessels (arrow) between the portal vein in the hepatoduodenal ligament (H) and the inferior vena cava (I). (d) CT scan obtained at the level of the pancreatic head shows crowded mesenteric vessels from the superior mesenteric vein (arrow) between the ascending portion of the duodenum (D) and the pancreatic head (P). Arrowheads = small bowel loops. At laparotomy performed 31 hours after CT, adhesion between the gastrocolic ligament and the transverse mesocolon was found. Approximately 50 cm of ileum, located 200 cm from the ligament of Treitz, was herniated into the lesser sac. The herniated ileal loops demonstrated only congestive changes without gangrene.
|
|
View larger version (131K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3c. Foramen of Winslow hernia in a 45-year-old man with acute epigastric pain of 18 hours duration. (a) Abdominal radiograph shows gas-containing small bowel loops (arrows) in the center of the upper abdomen between the liver and the gastric air bubble. (b) Image obtained with enteroclysis performed through a long intestinal tube shows an SBO at the right hepatic flexure (arrow). (c) Contrast-enhanced CT scan of the upper abdomen shows the cluster of dilated small bowel loops (arrowheads) in the lesser sac. There are stretched and converging mesenteric vessels (arrow) between the portal vein in the hepatoduodenal ligament (H) and the inferior vena cava (I). (d) CT scan obtained at the level of the pancreatic head shows crowded mesenteric vessels from the superior mesenteric vein (arrow) between the ascending portion of the duodenum (D) and the pancreatic head (P). Arrowheads = small bowel loops. At laparotomy performed 31 hours after CT, adhesion between the gastrocolic ligament and the transverse mesocolon was found. Approximately 50 cm of ileum, located 200 cm from the ligament of Treitz, was herniated into the lesser sac. The herniated ileal loops demonstrated only congestive changes without gangrene.
|
|
View larger version (133K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3d. Foramen of Winslow hernia in a 45-year-old man with acute epigastric pain of 18 hours duration. (a) Abdominal radiograph shows gas-containing small bowel loops (arrows) in the center of the upper abdomen between the liver and the gastric air bubble. (b) Image obtained with enteroclysis performed through a long intestinal tube shows an SBO at the right hepatic flexure (arrow). (c) Contrast-enhanced CT scan of the upper abdomen shows the cluster of dilated small bowel loops (arrowheads) in the lesser sac. There are stretched and converging mesenteric vessels (arrow) between the portal vein in the hepatoduodenal ligament (H) and the inferior vena cava (I). (d) CT scan obtained at the level of the pancreatic head shows crowded mesenteric vessels from the superior mesenteric vein (arrow) between the ascending portion of the duodenum (D) and the pancreatic head (P). Arrowheads = small bowel loops. At laparotomy performed 31 hours after CT, adhesion between the gastrocolic ligament and the transverse mesocolon was found. Approximately 50 cm of ileum, located 200 cm from the ligament of Treitz, was herniated into the lesser sac. The herniated ileal loops demonstrated only congestive changes without gangrene.
|
|
|
Paraduodenal Hernia
|
|---|
Anatomy
Paraduodenal fossae originate as congenital peritoneal anomalies owing to failure of mesenteric fusion with the parietal peritoneum and an associated abnormal rotation during imprisonment of the small intestine beneath the developing colon (1–3,22,27–33).
In the past, nine different fossae in the vicinity of the duodenum have been described, but clinically just five fossae are important: the superior duodenal fossa, inferior duodenal fossa (fossa of Treitz), paraduodenal fossa (fossa of Landzert), intermesocolic fossa (fossa of Broesike), and mesentericoparietal fossa (fossa of Waldeyer) (27,28). Figure 4 shows the locations of these fossae and their frequencies at autopsy. The fossa of Landzert, present in about 2% of autopsies, is recognized as inducing left paraduodenal hernia (PDH). The fossa of Waldeyer, present in about 1% of autopsies, is recognized as inducing right PDH (22).
View larger version (130K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4. Drawing (coronal view) shows the locations of duodenal fossae. Arrows indicate the directions of hernias through these fossae. The frequency with which each fossa is found at autopsy is given in parentheses. 1 = superior duodenal fossa (50%), 2 = inferior duodenal fossa (fossa of Treitz) (75%), 3 = paraduodenal fossa (fossa of Landzert) (2%), 4 = intermesocolic fossa (fossa of Broesike), 5 = mesentericoparietal fossa (fossa of Waldeyer) (1%). (Adapted and reprinted, with permission, from reference 6.)
|
|
Features
PDHs constitute approximately 53% of all internal hernias. Approximately three-fourths of these hernias occur on the left and are more predominant in men than in women, with a ratio of about 3:1 (1–3).
Left PDH develops through the fossa of Landzert into the descending mesocolon and left of the transverse mesocolon and results from failure of fusion of the inferior mesentery to the parietal peritoneum (29). The fossa of Landzert is located at the duodenojejunal junction, which is a zone of confluence of the descending mesocolon, transverse mesocolon, and small bowel mesentery (30). The herniated small bowel loops may become entrapped within this mesenteric sac. The characteristic CT appearance consists of an abnormal cluster or saclike mass of dilated small bowel loops lying between the pancreas and stomach to the left of the ligament of Treitz (Fig 5). There is usually mass effect that displaces the posterior wall of the stomach, the duodenal flexure inferiorly, and the transverse colon inferiorly (30,31). The mesenteric vessels that supply the herniated small bowel segments are crowded, engorged, and stretched at the entrance of the hernial sac (Fig 6 ) (9,10). Because the anterior wall of the sac contains the inferior mesenteric vein and left colic artery, CT demonstrates these vessels as a landmark above the encapsulated bowel loops.
View larger version (123K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5a. Left PDH in a 72-year-old man with acute, intermittent epigastric pain of 24 hours duration. (a) Contrast-enhanced CT scan of the upper abdomen shows a saclike mass of dilated jejunal loops between the pancreatic head (P) and stomach. The descending mesocolon (D) and stomach are displaced laterally. The dilated inferior mesenteric vein is located at the anterior border of the encapsulated loops. (b) CT scan obtained 20 mm below a shows crowded and engorged mesenteric vessels (arrow) at the fossa of Landzert (L). J = jejunal loops, S = stomach, arrowhead = inferior mesenteric vein. (c) CT scan of the midabdomen shows the inferior mesenteric vein (arrowhead). This vessel is a landmark for the inferior mesocolon, which is located at the anteromedial border of the encapsulated jejunal loops (J). (d) Diagram (coronal view) of the surgical findings shows that the fossa of Landzert is 4 cm in diameter (arrowheads). At laparotomy performed 42 hours after CT, approximately 200 cm of viable jejunum was found (arrows).
|
|
View larger version (124K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5b. Left PDH in a 72-year-old man with acute, intermittent epigastric pain of 24 hours duration. (a) Contrast-enhanced CT scan of the upper abdomen shows a saclike mass of dilated jejunal loops between the pancreatic head (P) and stomach. The descending mesocolon (D) and stomach are displaced laterally. The dilated inferior mesenteric vein is located at the anterior border of the encapsulated loops. (b) CT scan obtained 20 mm below a shows crowded and engorged mesenteric vessels (arrow) at the fossa of Landzert (L). J = jejunal loops, S = stomach, arrowhead = inferior mesenteric vein. (c) CT scan of the midabdomen shows the inferior mesenteric vein (arrowhead). This vessel is a landmark for the inferior mesocolon, which is located at the anteromedial border of the encapsulated jejunal loops (J). (d) Diagram (coronal view) of the surgical findings shows that the fossa of Landzert is 4 cm in diameter (arrowheads). At laparotomy performed 42 hours after CT, approximately 200 cm of viable jejunum was found (arrows).
|
|
View larger version (119K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5c. Left PDH in a 72-year-old man with acute, intermittent epigastric pain of 24 hours duration. (a) Contrast-enhanced CT scan of the upper abdomen shows a saclike mass of dilated jejunal loops between the pancreatic head (P) and stomach. The descending mesocolon (D) and stomach are displaced laterally. The dilated inferior mesenteric vein is located at the anterior border of the encapsulated loops. (b) CT scan obtained 20 mm below a shows crowded and engorged mesenteric vessels (arrow) at the fossa of Landzert (L). J = jejunal loops, S = stomach, arrowhead = inferior mesenteric vein. (c) CT scan of the midabdomen shows the inferior mesenteric vein (arrowhead). This vessel is a landmark for the inferior mesocolon, which is located at the anteromedial border of the encapsulated jejunal loops (J). (d) Diagram (coronal view) of the surgical findings shows that the fossa of Landzert is 4 cm in diameter (arrowheads). At laparotomy performed 42 hours after CT, approximately 200 cm of viable jejunum was found (arrows).
|
|
View larger version (46K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 5d. Left PDH in a 72-year-old man with acute, intermittent epigastric pain of 24 hours duration. (a) Contrast-enhanced CT scan of the upper abdomen shows a saclike mass of dilated jejunal loops between the pancreatic head (P) and stomach. The descending mesocolon (D) and stomach are displaced laterally. The dilated inferior mesenteric vein is located at the anterior border of the encapsulated loops. (b) CT scan obtained 20 mm below a shows crowded and engorged mesenteric vessels (arrow) at the fossa of Landzert (L). J = jejunal loops, S = stomach, arrowhead = inferior mesenteric vein. (c) CT scan of the midabdomen shows the inferior mesenteric vein (arrowhead). This vessel is a landmark for the inferior mesocolon, which is located at the anteromedial border of the encapsulated jejunal loops (J). (d) Diagram (coronal view) of the surgical findings shows that the fossa of Landzert is 4 cm in diameter (arrowheads). At laparotomy performed 42 hours after CT, approximately 200 cm of viable jejunum was found (arrows).
|
|
View larger version (123K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6a. Left PDH in a 55-year-old woman who experienced aggravated epigastric pain followed by 3 months of frequent and intermittent pain. (a) Contrast-enhanced CT scan of the upper abdomen shows a sac-like mass of proximal jejunal loops (J). In this case, CT did not show the inferior mesenteric vein, which is a landmark for left PDH. (b) CT scan obtained 30 mm below a shows a horseshoelike configuration of collapsed jejunal loops (arrowheads) and dilated mesenteric vessels (arrow) between the pancreas (P) and stomach (S) without mass effect. At laparotomy performed 7 hours after CT, the herniated jejunal loops were viable with no gangrene.
|
|
View larger version (126K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 6b. Left PDH in a 55-year-old woman who experienced aggravated epigastric pain followed by 3 months of frequent and intermittent pain. (a) Contrast-enhanced CT scan of the upper abdomen shows a sac-like mass of proximal jejunal loops (J). In this case, CT did not show the inferior mesenteric vein, which is a landmark for left PDH. (b) CT scan obtained 30 mm below a shows a horseshoelike configuration of collapsed jejunal loops (arrowheads) and dilated mesenteric vessels (arrow) between the pancreas (P) and stomach (S) without mass effect. At laparotomy performed 7 hours after CT, the herniated jejunal loops were viable with no gangrene.
|
|
Right PDH involves the fossa of Waldeyer, which is located immediately behind the superior mesenteric artery and inferior to the transverse segment of the duodenum with or without rotation anomaly. Right PDH occurs most frequently in cases of a nonrotated small intestine and a normally or incompletely rotated colon. According to the extent of malrotation, right PDH is associated with location of the superior mesenteric vein to the left of, and ventral to, the superior mesenteric artery and with absence of the normal horizontal duodenum. Because the fossa of Waldeyer extends to the right and downward, directly in front of the posterior parietal peritoneum, right PDH develops into the ascending mesocolon with a right colic vein anteriorly. The superior mesenteric artery and right colic vein are located at the anterior-medial border of the encapsulated small bowel loops and are a landmark for right PDH (Fig 7) (30).
View larger version (125K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7a. Right PDH in a 31-year-old man with sudden onset of severe diffuse abdominal pain. (a) Contrast-enhanced CT scan of the upper abdomen shows a saclike mass of fluid-filled bowel loops (S), most of which were jejunal and proximal ileal loops. (b) CT scan obtained 30 mm below a shows the encapsulated bowel loops herniated through the fossa of Waldeyer (W), which is located behind the superior mesenteric artery (arrowhead) just below the transverse portion of the duodenum (D). I = ileal loops. (c) CT scan of the lower abdomen shows the superior mesenteric artery (arrowhead), which is displaced anteriorly by the entrapped bowel loops. Dilated and converging vessels (arrows) are seen in the mesentery; dilated ileal loops (I) are seen in the left midabdomen. (d) Diagram (coronal view) of the surgical findings shows that the fossa of Waldeyer (light gray area) is 10 cm in diameter. At laparotomy performed 2 hours after CT, 350 cm of strangulated small intestine, located 70 cm from the ligament of Treitz, was found. Because the withdrawn bowel loops were purple, jejunostomy was performed without resection.
|
|
View larger version (119K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7b. Right PDH in a 31-year-old man with sudden onset of severe diffuse abdominal pain. (a) Contrast-enhanced CT scan of the upper abdomen shows a saclike mass of fluid-filled bowel loops (S), most of which were jejunal and proximal ileal loops. (b) CT scan obtained 30 mm below a shows the encapsulated bowel loops herniated through the fossa of Waldeyer (W), which is located behind the superior mesenteric artery (arrowhead) just below the transverse portion of the duodenum (D). I = ileal loops. (c) CT scan of the lower abdomen shows the superior mesenteric artery (arrowhead), which is displaced anteriorly by the entrapped bowel loops. Dilated and converging vessels (arrows) are seen in the mesentery; dilated ileal loops (I) are seen in the left midabdomen. (d) Diagram (coronal view) of the surgical findings shows that the fossa of Waldeyer (light gray area) is 10 cm in diameter. At laparotomy performed 2 hours after CT, 350 cm of strangulated small intestine, located 70 cm from the ligament of Treitz, was found. Because the withdrawn bowel loops were purple, jejunostomy was performed without resection.
|
|
View larger version (126K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7c. Right PDH in a 31-year-old man with sudden onset of severe diffuse abdominal pain. (a) Contrast-enhanced CT scan of the upper abdomen shows a saclike mass of fluid-filled bowel loops (S), most of which were jejunal and proximal ileal loops. (b) CT scan obtained 30 mm below a shows the encapsulated bowel loops herniated through the fossa of Waldeyer (W), which is located behind the superior mesenteric artery (arrowhead) just below the transverse portion of the duodenum (D). I = ileal loops. (c) CT scan of the lower abdomen shows the superior mesenteric artery (arrowhead), which is displaced anteriorly by the entrapped bowel loops. Dilated and converging vessels (arrows) are seen in the mesentery; dilated ileal loops (I) are seen in the left midabdomen. (d) Diagram (coronal view) of the surgical findings shows that the fossa of Waldeyer (light gray area) is 10 cm in diameter. At laparotomy performed 2 hours after CT, 350 cm of strangulated small intestine, located 70 cm from the ligament of Treitz, was found. Because the withdrawn bowel loops were purple, jejunostomy was performed without resection.
|
|
View larger version (85K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 7d. Right PDH in a 31-year-old man with sudden onset of severe diffuse abdominal pain. (a) Contrast-enhanced CT scan of the upper abdomen shows a saclike mass of fluid-filled bowel loops (S), most of which were jejunal and proximal ileal loops. (b) CT scan obtained 30 mm below a shows the encapsulated bowel loops herniated through the fossa of Waldeyer (W), which is located behind the superior mesenteric artery (arrowhead) just below the transverse portion of the duodenum (D). I = ileal loops. (c) CT scan of the lower abdomen shows the superior mesenteric artery (arrowhead), which is displaced anteriorly by the entrapped bowel loops. Dilated and converging vessels (arrows) are seen in the mesentery; dilated ileal loops (I) are seen in the left midabdomen. (d) Diagram (coronal view) of the surgical findings shows that the fossa of Waldeyer (light gray area) is 10 cm in diameter. At laparotomy performed 2 hours after CT, 350 cm of strangulated small intestine, located 70 cm from the ligament of Treitz, was found. Because the withdrawn bowel loops were purple, jejunostomy was performed without resection.
|
|
|
Transmesenteric Hernia
|
|---|
Anatomy
The small bowel mesentery is a broad, fan-shaped fold of peritoneum that suspends the loops of the small intestine from the posterior abdominal wall (1,22). The two layers of peritoneal reflection form the mesentery, which extends from its origin at the ligament of Treitz to the right toward the ileocecal valve (Fig 1, D).
Nearly 35% of transmesenteric hernias occur during the pediatric period and are probably caused by a congenital mechanism. Mesenteric defects are usually 2–5 cm in diameter and are located close to the ligament of Treitz or the ileocecal valve (2,3). Three etiologic hypotheses have been proposed for congenital mesenteric defects: (a) partial regression of the dorsal mesentery, (b) fenestration during the developmental enlargement of an inadequately vascularized area, and (c) an ileocecal mesentery with considerable and rapid lengthening in fetal life (32). In adults, most mesenteric defects are probably the result of surgery, trauma, or inflammation.
Features
Transmesenteric and transmesocolic hernias account for 8% of all internal hernias (1–3). Because of the absence of a limiting hernial sac, mechanical SBO usually occurs in cases of transmesenteric hernia (Fig 8), and it is impossible to differentiate closed-loop obstructions caused by herniation through the mesenteric defect from those caused by prolapse of the intestine under adhesive bands. A volvulus may further complicate the process and cause rapid hernial strangulation and intestinal gangrene (Fig 9) (1,3,32). A transmesenteric hernia usually manifests in association with proximal small bowel dilatation, with a transition zone to a normal or collapsed intestine. Because the bowel mesenteric defect itself is not visualized, observation of the clustering of small bowel loops and abnormalities of the mesenteric vessels plays an important role in diagnosis of transmesenteric hernia. CT shows that the mesenteric vascular pedicle is characteristically engorged, stretched, and crowded; in addition, converging mesenteric vessels are located at the entrance of the hernial sac (34) and there is displacement of the main mesenteric trunk (9,10,32).
View larger version (100K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8a. Transmesenteric hernia in a 36-year-old woman with lower abdominal pain of 10 days duration. She was treated conservatively for 20 days by means of decompression with a nasogastric tube or long intestinal tube, intravenous fluids, and antibiotics because of an undiagnosed SBO. However, the SBO developed despite treatment. (a) Contrast-enhanced CT scan of the midabdomen shows dilated and fluid-filled small bowel loops (S) and crowded and stretched vessels (arrow). (b) CT scan of the pelvis shows crowded and converging vessels (arrow) at the hernial orifice. (c) Image obtained with enteroclysis performed through the intestinal tube shows the SBO (arrow). (d) Diagram (coronal view) of the surgical findings shows that approximately 180 cm of strangulated ileum (arrows), located 5 cm from the ileocecal valve, was herniated through the mesenteric defect (arrowheads). At laparotomy, a segment of gangrenous ileum was resected. (e) Intraoperative photograph shows the hernial orifice, which is oval and 4 cm in diameter.
|
|
View larger version (106K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8b. Transmesenteric hernia in a 36-year-old woman with lower abdominal pain of 10 days duration. She was treated conservatively for 20 days by means of decompression with a nasogastric tube or long intestinal tube, intravenous fluids, and antibiotics because of an undiagnosed SBO. However, the SBO developed despite treatment. (a) Contrast-enhanced CT scan of the midabdomen shows dilated and fluid-filled small bowel loops (S) and crowded and stretched vessels (arrow). (b) CT scan of the pelvis shows crowded and converging vessels (arrow) at the hernial orifice. (c) Image obtained with enteroclysis performed through the intestinal tube shows the SBO (arrow). (d) Diagram (coronal view) of the surgical findings shows that approximately 180 cm of strangulated ileum (arrows), located 5 cm from the ileocecal valve, was herniated through the mesenteric defect (arrowheads). At laparotomy, a segment of gangrenous ileum was resected. (e) Intraoperative photograph shows the hernial orifice, which is oval and 4 cm in diameter.
|
|
View larger version (155K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8c. Transmesenteric hernia in a 36-year-old woman with lower abdominal pain of 10 days duration. She was treated conservatively for 20 days by means of decompression with a nasogastric tube or long intestinal tube, intravenous fluids, and antibiotics because of an undiagnosed SBO. However, the SBO developed despite treatment. (a) Contrast-enhanced CT scan of the midabdomen shows dilated and fluid-filled small bowel loops (S) and crowded and stretched vessels (arrow). (b) CT scan of the pelvis shows crowded and converging vessels (arrow) at the hernial orifice. (c) Image obtained with enteroclysis performed through the intestinal tube shows the SBO (arrow). (d) Diagram (coronal view) of the surgical findings shows that approximately 180 cm of strangulated ileum (arrows), located 5 cm from the ileocecal valve, was herniated through the mesenteric defect (arrowheads). At laparotomy, a segment of gangrenous ileum was resected. (e) Intraoperative photograph shows the hernial orifice, which is oval and 4 cm in diameter.
|
|
View larger version (41K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8d. Transmesenteric hernia in a 36-year-old woman with lower abdominal pain of 10 days duration. She was treated conservatively for 20 days by means of decompression with a nasogastric tube or long intestinal tube, intravenous fluids, and antibiotics because of an undiagnosed SBO. However, the SBO developed despite treatment. (a) Contrast-enhanced CT scan of the midabdomen shows dilated and fluid-filled small bowel loops (S) and crowded and stretched vessels (arrow). (b) CT scan of the pelvis shows crowded and converging vessels (arrow) at the hernial orifice. (c) Image obtained with enteroclysis performed through the intestinal tube shows the SBO (arrow). (d) Diagram (coronal view) of the surgical findings shows that approximately 180 cm of strangulated ileum (arrows), located 5 cm from the ileocecal valve, was herniated through the mesenteric defect (arrowheads). At laparotomy, a segment of gangrenous ileum was resected. (e) Intraoperative photograph shows the hernial orifice, which is oval and 4 cm in diameter.
|
|
View larger version (132K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8e. Transmesenteric hernia in a 36-year-old woman with lower abdominal pain of 10 days duration. She was treated conservatively for 20 days by means of decompression with a nasogastric tube or long intestinal tube, intravenous fluids, and antibiotics because of an undiagnosed SBO. However, the SBO developed despite treatment. (a) Contrast-enhanced CT scan of the midabdomen shows dilated and fluid-filled small bowel loops (S) and crowded and stretched vessels (arrow). (b) CT scan of the pelvis shows crowded and converging vessels (arrow) at the hernial orifice. (c) Image obtained with enteroclysis performed through the intestinal tube shows the SBO (arrow). (d) Diagram (coronal view) of the surgical findings shows that approximately 180 cm of strangulated ileum (arrows), located 5 cm from the ileocecal valve, was herniated through the mesenteric defect (arrowheads). At laparotomy, a segment of gangrenous ileum was resected. (e) Intraoperative photograph shows the hernial orifice, which is oval and 4 cm in diameter.
|
|
View larger version (111K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9a. Transmesenteric hernia in a 12-year-old girl who experienced 36 hours of diffuse abdominal pain and sudden development of cramps. Abdominal examination showed severe distention and tenderness at the midabdomen. Laboratory investigations revealed a hemoglobin level of 8.4 g/dL. (a) Nonenhanced CT scan of the midabdomen shows diffuse mesenteric fluid and haziness (arrows) and mildly dilated small bowel loops. The attenuation of the intraluminal fluid is increased (arrowheads) because red blood cells may have been released in the lumen. Laparotomy was performed 12 hours after CT. (b) Intraoperative photograph shows the hernial orifice (arrow), which is 3 cm in diameter. Approximately 260 cm of small intestine, located 100 cm from the ileocecal valve, was herniated through the mesenteric defect and twisted 360°; 230 cm was gangrenous and was thus resected.
|
|
View larger version (92K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9b. Transmesenteric hernia in a 12-year-old girl who experienced 36 hours of diffuse abdominal pain and sudden development of cramps. Abdominal examination showed severe distention and tenderness at the midabdomen. Laboratory investigations revealed a hemoglobin level of 8.4 g/dL. (a) Nonenhanced CT scan of the midabdomen shows diffuse mesenteric fluid and haziness (arrows) and mildly dilated small bowel loops. The attenuation of the intraluminal fluid is increased (arrowheads) because red blood cells may have been released in the lumen. Laparotomy was performed 12 hours after CT. (b) Intraoperative photograph shows the hernial orifice (arrow), which is 3 cm in diameter. Approximately 260 cm of small intestine, located 100 cm from the ileocecal valve, was herniated through the mesenteric defect and twisted 360°; 230 cm was gangrenous and was thus resected.
|
|
|
Transomental Hernia
|
|---|
Transomental hernias constitute approximately 1%–4% of all internal hernias. There are two types: In the first type, herniation occurs through a free greater omentum; this type is more common, and no sac is present. In the second type, which is rare, herniation into the lesser sac occurs through the gastrocolic ligament (33,35,36).
In the first type, the hernial orifice on the greater omentum is located in the periphery near the free edge (Fig 10) and is usually a slitlike opening from 2 to 10 cm in diameter (1–4,37). The cause of the omental defect has not been identified, but it has been suggested that most have a congenital origin, although inflammation, trauma, and circulation may also cause omental perforations. Small bowel loops, the cecum, and the sigmoid colon are involved in this defect. The clinical and radiologic findings are almost identical to those of transmesenteric hernias (Fig 11) (1,3,38).
View larger version (115K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10a. Transomental hernia in a 76-year-old woman with a 6-day history of lower abdominal pain. (a) Contrast-enhanced CT scan of the pelvis shows a cluster of fluid-filled small bowe | |
Top
Abstract
LEARNING OBJECTIVES FOR TEST...
