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Complications of Endoscopic Retrograde Cholangiopancreatography: Spectrum of Abnormalities Demonstrated with CT¹

¹ From the Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Md. Presented as a scientific exhibit at the 1999 RSNA scientific assembly. Received April 18, 2000; revision requested June 21; final revision received May 3, 2001; accepted May 3. Address correspondence to H.K.P., Department of Radiology, Johns Hopkins Hospital, 600 N Wolfe St, Baltimore, MD 21287 (e-mail: hpannu@jhmi.edu).

	Abstract

Top Abstract LEARNING OBJECTIVES Introduction ERCP Technique: An Overview... Usefulness of CT in... CT Protocol Specific Complications of ERCP Conclusions References

 
Endoscopic retrograde cholangiopancreatography (ERCP) is an invasive procedure that is performed to diagnose and treat pancreatic and biliary disease. In approximately 5%–10% of cases, the procedure itself causes adverse events. Diagnosis and management of ERCP-induced complications are performed with clinical, laboratory, and radiologic procedures. Evaluation of the type and severity of the complication is necessary and is successfully performed with computed tomography (CT). The most common causes of post-ERCP pain are acute pancreatitis and duodenal perforation. In severe pancreatitis, the pancreas is enlarged and enhances heterogeneously at CT. Pancreatic enhancement is diminished in areas of glandular necrosis. In duodenal perforation, CT may reveal extraluminal air or fluid. CT findings of acute duodenal hemorrhage are duodenal wall thickening and a high-attenuation mass in the duodenal wall. In infection, the bile ducts can be dilated and the attenuation of the bile can be increased at CT. Abscesses appear as hypoattenuating masses with enhancing capsules. CT findings of stent migration are an atypical location of the stent and bowel impaction. Other complications of ERCP are those related to endoscopy and include esophageal, liver, and splenic injury.

Index Terms: Bile ducts, stents and prostheses, 76.46 • Cholangitis, 76.20 • Duodenum, hemorrhage, 73.412 • Duodenum, perforation, 73.715 • Endoscopic retrograde cholangiopancreatography (ERCP), 70.1222 • Endoscopy, 70.458 • Pancreatitis, 770.291

	LEARNING OBJECTIVES

Top Abstract LEARNING OBJECTIVES Introduction ERCP Technique: An Overview... Usefulness of CT in... CT Protocol Specific Complications of ERCP Conclusions References

 
After reading this article and taking the test, the reader will be able to:

• List the two most common complications of ERCP for which CT is performed.
  
• Discuss the role of CT in diagnosis and management of ERCP-induced complications.
  
• Recognize the complications of ERCP on CT scans.
  

	Introduction

Top Abstract LEARNING OBJECTIVES Introduction ERCP Technique: An Overview... Usefulness of CT in... CT Protocol Specific Complications of ERCP Conclusions References

 
Endoscopy of the gastrointestinal tract became practical in the late 1960s, when flexible fiberoptic endoscopes became available (1,2). The primary advantage of endoscopy is that it allows access to target tissues for diagnosis, tissue sampling, and therapy. Diagnostic and therapeutic endoscopic retrograde cholangiopancreatography (ERCP) has been performed for approximately 30 years (3). It is valuable in diagnosis and treatment of pancreatic and biliary disease with less morbidity than surgery (3). In a prospective study performed in patients with abdominal pain, the pre-ERCP clinical diagnosis was changed in 25% of patients who underwent the procedure for the first time (4). Endoscopic therapy also helped avoid other invasive procedures in these patients.

There are multiple indications for performing ERCP. It is used for diagnosis of jaundice, evaluation of known or suspected pancreatic disease, and pre- or postoperative assessment of the biliary tree in patients undergoing laparoscopic cholecystectomy (5,6). In addition to detection of strictures and tumors, it is used to localize the site of duct leakage in pancreatic ascites, check for pancreas divisum, and collect secretions for cytologic and chemical analysis (5,6). Applications of therapeutic ERCP include sphincterotomy, removal of common bile duct stones, lithotripsy, biliary drainage, and stricture dilation (6). The contraindications are few and include severe cardiopulmonary disease and acute pancreatitis not due to gallstone disease (6).

Despite the potential benefits of ERCP, the technique is very operator dependent and patients are at risk for developing complications (3,7). Complication rates are lower with increased experience of the endoscopist (7–9). The complications can be secondary to biliary and pancreatic manipulation or related to endoscopy (3,7). Initially, the complication rate was not well documented and was primarily obtained by means of retrospective reviews (3). A review of data published in the late 1970s and 1980s approximated the overall rate of significant complications after sphincterotomy at 10% (8). In the past decade, definitions have been developed for classifying the severity and timing of complications (10). A specific grading system for the major complications such as pancreatitis, perforation, and bleeding has also been proposed (8). In general, complications are classified as mild if the length of hospital stay is less than or equal to 3 nights; complications are classified as moderate if the length of hospital stay is between 4 and 10 nights; and complications are classified as severe if the patient is hospitalized for 10 or more nights, is admitted to an intensive care unit, or requires surgery (7). As regards timing, complications are considered immediate if they occur during or shortly after the procedure; complications are considered early if they occur within a few hours; and complications are considered delayed if they occur within 30 days (7).

In the past few years, prospective studies have also been carried out to more accurately document the rate of complications of ERCP (11). The adverse event data for diagnostic and therapeutic procedures are often presented together in the literature (7). A recent prospective study of diagnostic and therapeutic procedures found a complication rate of 5.6% (12). The therapeutic procedures performed in this study included sphincterotomy, stent replacement, and balloon "sweep" of the common duct. In clinical practice, diagnostic procedures are performed less commonly than therapeutic ones. In a prospective multicenter study of 3,356 ERCP procedures in 2,769 patients, the major complication rate was 1.38% for diagnostic ERCP and 5.4% for therapeutic ERCP procedures such as sphincterotomy, "precut" procedures, and drainage (13). Pancreatitis was the most common adverse event in both groups (13). Cholangitis, hemorrhage, and duodenal perforation were the next most common in the group who underwent a therapeutic procedure. There is variability in the literature, with a prospective study of therapeutic ERCP with biliary sphincterotomy in 2,347 patients reporting an overall complication rate of 9.8% (9). Differences in patient population, study methods, and physician experience are possible reasons for the variability in the complication rate in the literature (14).

In this article, we illustrate the typical computed tomographic (CT) findings of ERCP-induced complications with an emphasis on the more common ones. First, we present an overview of the ERCP technique with associated risks and describe the usefulness of CT in patients with complications and the CT protocol. We then discuss specific complications of ERCP, which include pancreatitis, duodenal perforation, duodenal hemorrhage, infection, stent migration, and complications secondary to endoscopy. CT is performed if patients have severe abdominal pain, elevated white blood cell count, and fever after ERCP. Once the type of complication present is diagnosed, CT is performed if the patient does not improve with conservative treatment or has a deteriorating clinical course.

	ERCP Technique: An Overview with Associated Risks

Top Abstract LEARNING OBJECTIVES Introduction ERCP Technique: An Overview... Usefulness of CT in... CT Protocol Specific Complications of ERCP Conclusions References

 
Patients routinely undergo intravenous sedation, which increases the risk of cardiopulmonary complications (6,15). Patients lie in the left lateral decubitus position for introduction of the endoscope into the duodenum and are then turned into the prone oblique position (16). If cannulation of the biliary tree is difficult, a flexible guide wire or sphincterotome is used (16). A precut sphincterotomy or fistulotomy may be performed. The latter techniques increase the risk of duodenal and ductal perforation. The inferior submucosal papillary sphincter is cut with sphincterotomy, and this can lead to hemorrhage, acute pancreatitis, and perforation (17).

	Usefulness of CT in Patients with Complications

Top Abstract LEARNING OBJECTIVES Introduction ERCP Technique: An Overview... Usefulness of CT in... CT Protocol Specific Complications of ERCP Conclusions References

 
CT is useful in establishing the presence and severity of a complication after ERCP (18,19). In patients who are acutely ill within 24 hours of ERCP, acute pancreatitis and duodenal perforation can be reliably distinguished with CT (3,8,18,19). These are the two most common causes of postprocedure pain, and the initial clinical presentations are similar. In both conditions, patients have pain and an elevated serum amylase level (7,18). An ileus can be present on plain radiographs of the abdomen in both cases, and retroperitoneal air may not be obvious in patients with perforation (18). Extravasation of contrast material at fluoroscopy is seen in only a minority of cases (18). Pancreatic enlargement is present on CT scans with pancreatitis but is usually absent with perforation (18). Patients with perforation have periduodenal fluid and gas (18). In one study, extravasation of contrast material during the ERCP procedure and CT were found to be the most reliable means for distinguishing between pancreatitis and perforation (18). The distinction between pancreatitis and perforation is clinically relevant because a nasobiliary drain or biliary stent is usually placed in cases of duodenal or biliary ductal perforation (20). This decreases the amount of fluid leakage from the perforation site and the risk of sepsis (7). A surgeon is also usually consulted to help care for the patient (7,20). Patients with pancreatitis are treated with hydration, given analgesics, and observed. A nasogastric tube is placed if they have vomiting (20).

Other causes of pain such as liver and splenic lacerations and esophageal perforation can also be detected with CT. Once the type of complication is diagnosed, the patient can be monitored for development of further complications with additional scans as indicated (19). The role of CT in the management of specific complications is discussed in greater detail in the following sections.

	CT Protocol

Top Abstract LEARNING OBJECTIVES Introduction ERCP Technique: An Overview... Usefulness of CT in... CT Protocol Specific Complications of ERCP Conclusions References

 
Single–Detector Row Scanner
A 750-mL dose of ionic, water-soluble contrast material is given orally. A 120-mL dose of nonionic contrast material is injected intravenously at 2–3 mL/sec. After a 40-second scanning delay, 5-mm-thick sections are acquired with a pitch of 1.6 and a reconstruction interval of 5 mm.

Multi–Detector Row Scanner
Contrast material is given in the same manner as for a single–detector row scanner. The scanning delay is 50 seconds. The detector collimation is 2.5 mm, the section thickness is 5 mm, and the reconstruction interval is 5 mm.

	Specific Complications of ERCP

Top Abstract LEARNING OBJECTIVES Introduction ERCP Technique: An Overview... Usefulness of CT in... CT Protocol Specific Complications of ERCP Conclusions References

 
Pancreatitis
Acute pancreatitis occurs in approximately 5% of diagnostic procedures and 10% of therapeutic procedures (3). A commonly used definition of post-ERCP pancreatitis is abdominal pain for more than 24 hours after the procedure and levels of serum pancreatic enzymes three times above normal (3). This definition excludes the 30%–75% of patients who are asymptomatic and have an elevated amylase level alone (7). Asymptomatic hyperamylasemia peaks 90 minutes to 4 hours after ERCP and resolves within 48 hours (21).

Post-ERCP pancreatitis usually evolves over 2–6 hours and manifests as epigastric or back pain and nausea (3,20). Risk factors for post-ERCP pancreatitis are sphincter of Oddi dysfunction and young age (14). A higher rate of pancreatitis is caused by increased manipulation around the papilla and multiple injections of the pancreatic duct (22). Pancreatitis is also more likely to develop in patients with contrast material visualized in the renal collecting system on a plain radiograph obtained at the conclusion of the procedure (23).

In addition to serum amylase and lipase levels, levels of trypsinogen 2 and trypsin 2–₁-antitrypsin complex can be used to diagnose acute pancreatitis. The former is measured at 6 hours, and the latter is measured at 24 hours; the sensitivity of each is over 90% (22). Measurement of a 4-hour serum amylase level has been suggested to identify outpatients at risk for developing pancreatitis before discharge (21). The pancreatitis is mild or moderate in 90% of cases and resolves with intravenous hydration and analgesia (3,20).

Management of post-ERCP pancreatitis is similar to management of pancreatitis due to other causes (7). General guidelines for performing CT include (a) cases in which the clinical diagnosis is not definite; (b) patients with hyperamylasemia, severe clinical pancreatitis, abdominal distention, tenderness, fever, or leukocytosis; (c) patients whose condition does not improve within 72 hours of commencing conservative treatment; and (d) patients who develop an acute change after initial improvement in their condition (24). The purpose of performing CT is to diagnose possible necrosis and fluid collections and to guide needle aspiration or drainage (20,25). Repeat CT is performed as needed to monitor the progress of the patient (20).

The pancreas can appear relatively normal in cases of mild inflammation (25). Patients may have focal edema or diffuse glandular swelling in post-ERCP inflammation (19). Focal swelling of the pancreatic head has been referred to as pancreatic pseudotumor and can be seen after papillotomy (26). In more severe cases, the entire gland is enlarged and enhances heterogeneously (27). In areas of glandular necrosis, enhancement of the pancreas is diminished with administration of intravenous contrast material (Fig 1) (27). An area of nonenhancing parenchyma larger than 3 cm in diameter or greater than 30% of the pancreatic area is a reliable CT finding for necrosis (25). Pancreatic necrosis accounts for over 70% of deaths from acute pancreatitis because digestive enzymes leak with disruption of the pancreatic duct (28). The necrotic tissue can evolve into an intrapancreatic collection with a pseudocapsule (28). Foci of high attenuation are due to hemorrhage (28).

View larger version (149K): [in this window] [in a new window] [Download PPT slide]   Figure 1a.   Post-ERCP pancreatitis in a 50-year-old man. ERCP was performed to check for a mass in the pancreatic tail, and the entire pancreatic duct was well opacified. The patient was readmitted 3 days after ERCP with abdominal pain and low-grade fever. CT was performed with oral and intravenous contrast material. (a) CT scan shows heterogeneous attenuation of the pancreas. Low-attenuation areas (*) suggest necrosis. Stranding of the peripancreatic fat is due to inflammation. There is thickening of the wall of the antrum of the stomach (arrow) secondary to local inflammation. (b) CT scan obtained inferior to a shows extensive stranding of the fat and thickening of the Gerota fascia on the right side (arrow). (c) CT scan shows fluid (arrow) in the dependent portion of the pelvis, a finding compatible with ascites.

View larger version (150K): [in this window] [in a new window] [Download PPT slide]   Figure 1b.   Post-ERCP pancreatitis in a 50-year-old man. ERCP was performed to check for a mass in the pancreatic tail, and the entire pancreatic duct was well opacified. The patient was readmitted 3 days after ERCP with abdominal pain and low-grade fever. CT was performed with oral and intravenous contrast material. (a) CT scan shows heterogeneous attenuation of the pancreas. Low-attenuation areas (*) suggest necrosis. Stranding of the peripancreatic fat is due to inflammation. There is thickening of the wall of the antrum of the stomach (arrow) secondary to local inflammation. (b) CT scan obtained inferior to a shows extensive stranding of the fat and thickening of the Gerota fascia on the right side (arrow). (c) CT scan shows fluid (arrow) in the dependent portion of the pelvis, a finding compatible with ascites.

View larger version (143K): [in this window] [in a new window] [Download PPT slide]   Figure 1c.   Post-ERCP pancreatitis in a 50-year-old man. ERCP was performed to check for a mass in the pancreatic tail, and the entire pancreatic duct was well opacified. The patient was readmitted 3 days after ERCP with abdominal pain and low-grade fever. CT was performed with oral and intravenous contrast material. (a) CT scan shows heterogeneous attenuation of the pancreas. Low-attenuation areas (*) suggest necrosis. Stranding of the peripancreatic fat is due to inflammation. There is thickening of the wall of the antrum of the stomach (arrow) secondary to local inflammation. (b) CT scan obtained inferior to a shows extensive stranding of the fat and thickening of the Gerota fascia on the right side (arrow). (c) CT scan shows fluid (arrow) in the dependent portion of the pelvis, a finding compatible with ascites.

View larger version (146K): [in this window] [in a new window] [Download PPT slide]   Figure 2a.   Renal involvement by ERCP-induced pancreatitis in a 75-year-old woman. ERCP was performed for a dilated common bile duct, and the duct was "swept" for stones. After the procedure, the patient had clinically evident pancreatitis, which was also demonstrated at multiple CT studies. She developed a perinephric fluid collection, which showed no evidence of infection at fine-needle aspiration. The collection was not drained and persisted for several weeks. CT was performed with intravenous contrast material 28 days after ERCP. (a) CT scan shows stranding of the fat (arrow) adjacent to the head of the pancreas and the duodenum. A heterogeneous fluid collection is present in the perirenal space (*). (b) CT scan obtained inferior to a shows the fluid collection displacing the intestine and abutting the psoas muscle (arrow).

View larger version (132K): [in this window] [in a new window] [Download PPT slide]   Figure 2b.   Renal involvement by ERCP-induced pancreatitis in a 75-year-old woman. ERCP was performed for a dilated common bile duct, and the duct was "swept" for stones. After the procedure, the patient had clinically evident pancreatitis, which was also demonstrated at multiple CT studies. She developed a perinephric fluid collection, which showed no evidence of infection at fine-needle aspiration. The collection was not drained and persisted for several weeks. CT was performed with intravenous contrast material 28 days after ERCP. (a) CT scan shows stranding of the fat (arrow) adjacent to the head of the pancreas and the duodenum. A heterogeneous fluid collection is present in the perirenal space (*). (b) CT scan obtained inferior to a shows the fluid collection displacing the intestine and abutting the psoas muscle (arrow).

Once the diagnosis of necrosis or fluid collection is made, CT can be used to guide percutaneous diagnostic interventions and therapy. Image-guided fine-needle aspiration of necrosis is performed as frequently as clinically indicated to exclude superimposed infection (29). Clinical indications for fine-needle aspiration include the presence of systemic inflammation (25,29). Necrotic tissue can be treated with a large-bore catheter and irrigation or surgically débrided, whereas fluid collections can be drained percutaneously (28). In a retrospective review of 32 patients with pancreatic necrosis, the amount of necrosis was stable over time in two-thirds of the patients and surgical débridement was performed more often in those with necrosis of more than 75% of the gland (30). In a small subset of patients who were treated conservatively, a focal fatty cleft developed after several weeks (30).

Patients with acute pancreatitis can develop pseudocysts after the initial attack has subsided (27). These are encapsulated collections that can have a barely perceptible wall or a thick, enhancing wall and communicate with the pancreatic duct (25,27). Other possible complications of acute pancreatitis are pseudoaneurysms, pleural effusions, and ascites (27). Involvement of the extraperitoneal portions of the colon can lead to perforation and stricture formation (Fig 3) (31).

View larger version (107K): [in this window] [in a new window] [Download PPT slide]   Figure 3.   Colonic involvement by ERCP-induced pancreatitis due to retroperitoneal spread of inflammation in a 38-year-old woman. Multiple attempts were made to cannulate the pancreatic duct without success. The patient had postprocedure pain and an elevated amylase level with imaging evidence of acute pancreatitis. CT was performed with oral and intravenous contrast material 1 day after ERCP. CT scan shows inflammatory change (*) in the retroperitoneum abutting the ascending colon. The wall of the ascending colon is thickened (arrow) due to dissection of peripancreatic fluid and inflammation along the anterior pararenal space into the paracolic gutter to surround the cecum and ascending colon. The patient was treated with medical therapy, and follow-up CT performed 3 weeks later showed a decrease in colonic inflammation.

Duodenal Perforation
Perforation of the duodenum or distal duct occurs in 1.3% of cases, usually with sphincterotomy (8). Risk factors include a deep incision outside the papilla, precut papillotomy, guide-wire perforation, nondilated ducts, sphincter of Oddi disease, and Billroth II surgery (3,7). Free retroperitoneal air has been seen in 29% of asymptomatic patients on a CT scan obtained within 24 hours of the procedure (32). This finding may occur due to insufflation of air into the duodenum for endoscopy, which can lead to pneumatosis and extraluminal air (32–34). Pneumatosis can also occur with misdirection of the catheter tip during duct cannulation and submucosal injection of contrast material and air (19).

The presence of retroperitoneal air at CT does not correlate with the severity of the complication or the need for surgery (3,32). The quantity of air seen is due to continued endoscopic insufflation of air after the injury has occurred (3,17). Patients with only evidence of free air usually recover with conservative treatment, which consists of bowel rest and antibiotics (33,34). However, infection of bile and leakage of fluid through the perforation in cases of failed biliary drainage correlate with increased morbidity (3,35). In cases of medical treatment failures, there is a high mortality rate of 50% due to sepsis (8,33).

Attempts have been made to distinguish patients who can be treated conservatively from those who require surgery. In the literature, three and four separate categories have been proposed (33,34). In the four-category classification, retroperitoneal air alone is one category and is not considered to represent a true perforation (33). The remaining three categories are distal ductal perforation by a guide wire, periampullary duodenal perforation, and duodenal perforation remote from the ampulla (33,34). Fever, elevated white blood cell count, and abdominal pain are usually not helpful in determining which patients should undergo surgery (33). As the injury is primarily retroperitoneal, peritonitis is a late sign (33).

The first two categories are usually diagnosed during ERCP by extravasation of contrast material and retroperitoneal air (8,34). Performance of imaging studies is variable and at the discretion of the patient’s physician (3,8,33,35). If patients have an increase in their white blood cell count or pain and fever, CT is recommended (20). The presence of a fluid collection at CT indicates that surgical management or percutaneous image-guided drainage is needed (21,33). Patients are treated nonsurgically if there is minimal extravasation and no fluid collection (33). Conservative therapy includes stent placement or nasobiliary tube drainage and intravenous antibiotics (3,34). A fluoroscopic study at 8 hours and CT at 8 hours and 48 hours have also been suggested to confirm that the leak is sealed and that there are no fluid collections (8,33). Repeat scans are suggested to monitor the patient until there is clinical recovery (20,33).

The third category is duodenal perforation by the endoscope that is remote from the papilla (34). The diagnosis may not be made until the patient presents with peritoneal signs, unless clinical suspicion is high and CT is performed early (34). These perforations are large, and patients require immediate surgery (33). Uncommonly, perforation of the cystic or hepatic duct occurs with ERCP (Fig 4) (36).

View larger version (144K): [in this window] [in a new window] [Download PPT slide]   Figure 4a.   Perforation of the right hepatic duct in a 35-year-old man with a history of sclerosing cholangitis. Dilation of the common bile duct was performed for a stricture. Owing to persistent pain, fever, and retroperitoneal fluid at CT, repeat ERCP was performed and showed leakage of contrast material from the right hepatic duct. A stent was placed, and the patient recovered within 1 week. CT was performed with oral and intravenous contrast material 2 days after ERCP. (a) CT scan shows fluid and extensive inflammation in the retroperitoneum due to bile leakage. The right ureter is surrounded (open arrow). The fluid tracked inferiorly from the gallbladder fossa. Solid arrow = left ureter. (b) CT scan shows inflammatory change and fluid in the presacral space (*). Arrow = rectum.

View larger version (132K): [in this window] [in a new window] [Download PPT slide]   Figure 4b.   Perforation of the right hepatic duct in a 35-year-old man with a history of sclerosing cholangitis. Dilation of the common bile duct was performed for a stricture. Owing to persistent pain, fever, and retroperitoneal fluid at CT, repeat ERCP was performed and showed leakage of contrast material from the right hepatic duct. A stent was placed, and the patient recovered within 1 week. CT was performed with oral and intravenous contrast material 2 days after ERCP. (a) CT scan shows fluid and extensive inflammation in the retroperitoneum due to bile leakage. The right ureter is surrounded (open arrow). The fluid tracked inferiorly from the gallbladder fossa. Solid arrow = left ureter. (b) CT scan shows inflammatory change and fluid in the presacral space (*). Arrow = rectum.

View larger version (120K): [in this window] [in a new window] [Download PPT slide]   Figure 5.   Intramural duodenal air after ERCP in a 55-year-old woman. ERCP was performed for evaluation of an ampullary tumor. Cannulation of the common bile duct was unsuccessful, and extravasation of contrast material from the duodenum was seen during the procedure. CT was performed with oral and intravenous contrast material 3 days after ERCP. CT scan shows air (arrow) in the dependent wall of the duodenum, which represents pneumatosis. The common bile duct is dilated, a finding compatible with the history of ampullary tumor. The patient was treated medically, and repeat CT performed 11 days later showed no evidence of an abscess.

View larger version (140K): [in this window] [in a new window] [Download PPT slide]   Figure 6a.   Duodenal perforation after ERCP in a 49-year-old woman. ERCP was performed for evaluation of right upper quadrant pain and revealed a stricture in the common bile duct and nonfilling of the gallbladder, findings compatible with acute cholecystitis. The patient had pain immediately after the procedure and a significant amount of free air. CT was performed without contrast material on the day of ERCP. (a) CT scan obtained with a soft-tissue window shows free air (*) diffusely in the peritoneal cavity, retroperitoneum, and subcutaneous tissues. (b) CT scan obtained inferior to a shows extensive free air in the root of the mesentery (arrow). Air also dissected superiorly into the mediastinum and right pleural cavity. (c) Follow-up CT scan obtained 2 days later at the same level as in a shows a significant decrease in the amount of free air (*). There is thickening of the wall of the gallbladder (arrow) due to cholecystitis. The patient recovered within a few days with conservative treatment.

View larger version (124K): [in this window] [in a new window] [Download PPT slide]   Figure 6b.   Duodenal perforation after ERCP in a 49-year-old woman. ERCP was performed for evaluation of right upper quadrant pain and revealed a stricture in the common bile duct and nonfilling of the gallbladder, findings compatible with acute cholecystitis. The patient had pain immediately after the procedure and a significant amount of free air. CT was performed without contrast material on the day of ERCP. (a) CT scan obtained with a soft-tissue window shows free air (*) diffusely in the peritoneal cavity, retroperitoneum, and subcutaneous tissues. (b) CT scan obtained inferior to a shows extensive free air in the root of the mesentery (arrow). Air also dissected superiorly into the mediastinum and right pleural cavity. (c) Follow-up CT scan obtained 2 days later at the same level as in a shows a significant decrease in the amount of free air (*). There is thickening of the wall of the gallbladder (arrow) due to cholecystitis. The patient recovered within a few days with conservative treatment.

View larger version (135K): [in this window] [in a new window] [Download PPT slide]   Figure 6c.   Duodenal perforation after ERCP in a 49-year-old woman. ERCP was performed for evaluation of right upper quadrant pain and revealed a stricture in the common bile duct and nonfilling of the gallbladder, findings compatible with acute cholecystitis. The patient had pain immediately after the procedure and a significant amount of free air. CT was performed without contrast material on the day of ERCP. (a) CT scan obtained with a soft-tissue window shows free air (*) diffusely in the peritoneal cavity, retroperitoneum, and subcutaneous tissues. (b) CT scan obtained inferior to a shows extensive free air in the root of the mesentery (arrow). Air also dissected superiorly into the mediastinum and right pleural cavity. (c) Follow-up CT scan obtained 2 days later at the same level as in a shows a significant decrease in the amount of free air (*). There is thickening of the wall of the gallbladder (arrow) due to cholecystitis. The patient recovered within a few days with conservative treatment.

View larger version (135K): [in this window] [in a new window] [Download PPT slide]   Figure 7.   Duodenitis after ERCP in a 37-year-old man. Cannulation of the common bile duct was difficult, and sphincterotomy could not be performed. The patient experienced pain and vomiting after the procedure and recovered within 10 days with conservative treatment. CT was performed with oral and intravenous contrast material on the day of ERCP. CT scan shows marked thickening of the wall of the duodenum (arrow) secondary to inflammation from ERCP. There is also fluid in the right perirenal space and thickening of the Gerota fascia.

View larger version (146K): [in this window] [in a new window] [Download PPT slide]   Figure 8.   Duodenal perforation with air and fluid leakage in a 51-year-old woman. The patient underwent ERCP and sphincterotomy and developed postprocedure abdominal pain. Initial CT showed free retroperitoneal air. Repeat CT showed retroperitoneal fluid and a decrease in free air. CT scan obtained with oral and intravenous contrast material 5 days after ERCP shows minimal free air (arrow) and free fluid (*) in the retroperitoneum. The patient was treated conservatively and discharged after 10 days.

View larger version (136K): [in this window] [in a new window] [Download PPT slide]   Figure 9a.   Fluid collection secondary to duodenal perforation in a 79-year-old woman. The patient underwent sphincterotomy and placement of a stent in the pancreatic duct. CT was performed with oral contrast material 7 days after ERCP. (a) CT scan shows thickening of the wall of the duodenum (solid arrow). An extraluminal collection of air and contrast material lies posterior to the duodenum (open arrow). There is thickening of the Gerota fascia on the right side. (b) CT scan obtained inferior to a shows fluid in the right anterior pararenal space (arrow), a finding compatible with leakage of enteric contents from the duodenum. The perforation was treated conservatively, and follow-up CT did not show progression of the fluid collection. The patient recovered within 3 weeks.

View larger version (140K): [in this window] [in a new window] [Download PPT slide]   Figure 9b.   Fluid collection secondary to duodenal perforation in a 79-year-old woman. The patient underwent sphincterotomy and placement of a stent in the pancreatic duct. CT was performed with oral contrast material 7 days after ERCP. (a) CT scan shows thickening of the wall of the duodenum (solid arrow). An extraluminal collection of air and contrast material lies posterior to the duodenum (open arrow). There is thickening of the Gerota fascia on the right side. (b) CT scan obtained inferior to a shows fluid in the right anterior pararenal space (arrow), a finding compatible with leakage of enteric contents from the duodenum. The perforation was treated conservatively, and follow-up CT did not show progression of the fluid collection. The patient recovered within 3 weeks.

Delayed bleeding occurs 24 or more hours after the procedure due to sloughing of the coagulum or restarting anticoagulation (3). Freeman et al (9) defined significant hemorrhage as clinical evidence of bleeding with melena or hematemesis with an associated decrease in hemoglobin concentration of at least 2 g/dL or need for a blood transfusion. In their prospective study of 2,347 patients, clinically significant hemorrhage occurred in 2%, 70% of whom needed transfusion (9). Delayed hemorrhage is treated with repeat endoscopy and epinephrine injection, embolization, or surgery (3,7,8).

ERCP-induced hemorrhage is monitored clinically and with laboratory tests (20). Therefore, intraluminal bleeding is primarily recognized, although intramural hemorrhage has been reported (37). CT is not typically performed for diagnosis of hemorrhage; however, blood may be detected if CT is performed for another indication. CT findings of acute duodenal hemorrhage are duodenal wall thickening and a high-attenuation mass in the duodenal wall (Fig 10) (38). Over time, the attenuation of the fluid decreases and a pseudocapsule may form (38).

View larger version (140K): [in this window] [in a new window] [Download PPT slide]   Figure 10a.   Hemorrhage and perforation after ERCP in a 67-year-old woman. Cannulation of the common bile duct was unsuccessful, and the patient experienced pain after the procedure. CT was performed with intravenous contrast material on the day of ERCP. (a) CT scan shows free retroperitoneal air (solid arrow) between the duodenum and pancreatic head and just posterior to the gastroduodenal artery (open arrow). The small amount of fluid and the stranding of fat in the right anterior pararenal space (*) are secondary to inflammation. The common bile duct is dilated. (b) CT scan obtained inferior to a shows a high-attenuation hematoma (arrow) between the duodenum and pancreas. (c) CT scan obtained inferior to b shows a high-attenuation mass (arrow) that appears to be abutting the lumen of the duodenum, a finding compatible with an intramural hematoma. The patient was treated conservatively and recovered within 3 days.

View larger version (142K): [in this window] [in a new window] [Download PPT slide]   Figure 10b.   Hemorrhage and perforation after ERCP in a 67-year-old woman. Cannulation of the common bile duct was unsuccessful, and the patient experienced pain after the procedure. CT was performed with intravenous contrast material on the day of ERCP. (a) CT scan shows free retroperitoneal air (solid arrow) between the duodenum and pancreatic head and just posterior to the gastroduodenal artery (open arrow). The small amount of fluid and the stranding of fat in the right anterior pararenal space (*) are secondary to inflammation. The common bile duct is dilated. (b) CT scan obtained inferior to a shows a high-attenuation hematoma (arrow) between the duodenum and pancreas. (c) CT scan obtained inferior to b shows a high-attenuation mass (arrow) that appears to be abutting the lumen of the duodenum, a finding compatible with an intramural hematoma. The patient was treated conservatively and recovered within 3 days.

View larger version (145K): [in this window] [in a new window] [Download PPT slide]   Figure 10c.   Hemorrhage and perforation after ERCP in a 67-year-old woman. Cannulation of the common bile duct was unsuccessful, and the patient experienced pain after the procedure. CT was performed with intravenous contrast material on the day of ERCP. (a) CT scan shows free retroperitoneal air (solid arrow) between the duodenum and pancreatic head and just posterior to the gastroduodenal artery (open arrow). The small amount of fluid and the stranding of fat in the right anterior pararenal space (*) are secondary to inflammation. The common bile duct is dilated. (b) CT scan obtained inferior to a shows a high-attenuation hematoma (arrow) between the duodenum and pancreas. (c) CT scan obtained inferior to b shows a high-attenuation mass (arrow) that appears to be abutting the lumen of the duodenum, a finding compatible with an intramural hematoma. The patient was treated conservatively and recovered within 3 days.

The diagnosis of infection is made by the presence of pain, fever, and elevated white blood cell count (20). If there is no biliary obstruction, the patient is treated with antibiotics and CT may be performed to check for a liver abscess (20). At CT, the bile ducts can be dilated and the attenuation of bile can be increased due to the presence of debris (40). Thickening of the wall of the ducts and pneumobilia may also be observed. Abscesses appear as hypoattenuating masses with an enhancing capsule (40). The lesions may be clustered together, and gas is present in a minority of cases.

Stent Migration
Migration of a common bile duct or pancreatic duct stent occurs in up to 5.9% of cases (7). Migration can occur into the proximal duct or into the gut. Risk factors associated with proximal stent migration are malignant strictures, large stent diameter, and short stent length (7). Distally migrating stents are usually expelled with stool, whereas proximally migrating stents are removed endoscopically. Stents can also be incorrectly placed at the time of the procedure. Imaging findings in stent migration are atypical location of the stent (Fig 11) and bowel impaction in colonic diverticula (7).

View larger version (138K): [in this window] [in a new window] [Download PPT slide]   Figure 11a.   Stent misplacement or migration in a 23-year-old man with a history of common bile duct stones. CT was performed with intravenous contrast material 1 day after ERCP. (a) CT scan shows a linear area of increased attenuation (arrow) in the right lobe of the liver, which represents a biliary stent. (b) CT scan obtained inferior to a shows the tip of the stent in the proximal common bile duct (solid arrow). The contrast material in the duct (open arrow) and gallbladder is from the recent ERCP. The stranding of the adjacent fat is due to inflammatory change.

View larger version (143K): [in this window] [in a new window] [Download PPT slide]   Figure 11b.   Stent misplacement or migration in a 23-year-old man with a history of common bile duct stones. CT was performed with intravenous contrast material 1 day after ERCP. (a) CT scan shows a linear area of increased attenuation (arrow) in the right lobe of the liver, which represents a biliary stent. (b) CT scan obtained inferior to a shows the tip of the stent in the proximal common bile duct (solid arrow). The contrast material in the duct (open arrow) and gallbladder is from the recent ERCP. The stranding of the adjacent fat is due to inflammatory change.

	Conclusions

Top Abstract LEARNING OBJECTIVES Introduction ERCP Technique: An Overview... Usefulness of CT in... CT Protocol Specific Complications of ERCP Conclusions References

 
CT is useful in diagnosing the cause of acute abdominal pain after ERCP. It allows differentiation between acute pancreatitis and perforation, which are the two most common complications. CT is also beneficial in monitoring patients for subsequent complications and for guiding percutaneous interventions.

	Footnotes

 
Abbreviation: ERCP = endoscopic retrograde cholangiopancreatography

	References

Top Abstract LEARNING OBJECTIVES Introduction ERCP Technique: An Overview... Usefulness of CT in... CT Protocol Specific Complications of ERCP Conclusions References

 

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