Choledocholithiasis Mimicking Sphincter of Oddi Dysfunction

Case Report

A 36-year-old woman without any significant medical or surgical history developed biliary-type right upper quadrant, epigastric abdominal pain, and liver function tests (LFTs) revealed alanine aminotransferase and aspartate aminotransferase elevations of three times the normal levels, for which she was admitted to our hospital for further care and management. The patient had had five similar episodes over the previous 2 years and had been treated in various emergency departments, never having been admitted prior to this episode.

The patient presented to our emergency department in January 2006, with complaints of nausea and abdominal pain. Abdominal computed tomography (CT) scan was unremarkable (Figure 1). Ultrasound of the abdominal right upper quadrant revealed a dilated common bile duct (CBD) measuring approximately 10 mm, but without visible stones or intrahepatic biliary duct dilation (Figure 2). In addition, no filling defect was seen within the ductal system. Gallbladder lumen appeared normal in size, and there was no gallbladder wall thickening, peri-cholecystic fluid, sludge, or cholelithiasis evident.

Figure 1.

Normal computed tomography scan of the patient's abdomen at presentation. Arrows point to the common bile duct.

Figure 2.

Ultrasound showing dilated common bile duct without any obvious stones.

Because biliary-type abdominal pain is commonly associated with dilated CBD on ultrasound and abnormal LFTs, the patient was clinically diagnosed with sphincter of Oddi dysfunction (SOD) and scheduled to undergo endoscopic retrograde cholangiopancreatography (ERCP) with sphincter of Oddi manometry (SOM). ERCP revealed extensive amounts of biliary sludge and numerous stones stacked up in the CBD, although the gallbladder itself did not contain stones (Figures 3 and 4).

Figure 3.

Endoscopic retrograde cholangiopancreatography showing stones in the common bile duct.

Figure 4.

Endoscopic retrograde cholangiopancreatography showing dilated common bile duct filled with stones.

Discussion

First described less than three decades ago, SOD is a clinical syndrome best categorized by the Milwaukee Classification system based on laboratory, clinical, and radiologic features in patients with recurrent abdominal pain, biliary pain, elevated aminotransferase levels, and dilated CBD on imaging studies, all of which are criteria that have been evaluated in multiple studies. ^1–5

SOD is a benign noncalculous obstruction of bile or pancreatic drainage at the level of the sphincter of Oddi. This condition is clinically associated with either biliary pain or idiopathic pancreatitis, depending on the portion of the affected sphincter. Patients with suspected SOD can be subdivided into type I, II, or III SOD, depending on associated clinical evidence. Multiple noninvasive tests have been utilized to aid in diagnosis but have been complicated by poor sensitivity and specificity. Until several years ago, the gold standard for studying and treating this pathologic condition was ERCP. Currently, SOM is the gold standard for confirming diagnosis, although questions remain regarding its sensitivity and specificity. Sphincterotomy of the affected portion of the sphincter is the treatment of choice and has been shown to be effective for the palliation of symptoms in type I, and occasionally in type II, SOD.

The differential diagnosis in our patient included SOD, papillary stenosis, ampullary lesions, and chol-edocholithiasis. What makes this case particularly interesting is that conventional imaging studies such as ultrasound and CT scan of the abdomen were negative, except for a mildly dilated CBD. This case reinforces that choledocholithiasis and cholelithiasis are the most important differential diagnoses for right upper quadrant pain with elevated liver enzyme levels, and emphasizes that choledocholithiasis should always be taken into consideration, even if the usual imaging studies (ie, sonography and CT scanning) are negative.

ERCP is highly accurate in diagnosing choledo-cholithiasis, but it is the most invasive of the available methods. Complications of ERCP include a mortality rate of 0.1–1.3% and a morbidity rate of 5–19%,⁶ with a 3–30% incidence of post-ERCP pancreatitis. Less invasive methods for the diagnosis of choledocholithiasis include ultrasonography (US), magnetic resonance cholangiopancreatography (MRCP), CT, and endoscopic ultrasonography (EUS). In a study comparing the results of US, MRCP, and ERCP in 83 patients who had a suspicion of biliary disease, the sensitivity and specificity for ERCP in detecting stones were 98% and 100%, respectively, which were better than any other imaging modality. The sensitivity and specificity for US were 71% and 97.2%,⁷ respectively, whereas the sensitivity and specificity for MRCP were 97.4% and 97.2%, respectively, in the diagnosis of choledocholithiasis (n=38) for both procedures. In contrast, CT has a high specificity (94%), but low sensitivity (35–85%), due to its inability to detect noncalcified stones.⁸ EUS is another extremely accurate test in the diagnosis of choledocholithiasis, with a risk of complications similar to that of upper gastrointestinal endoscopy. In a retrospective chart review of 30 patients who underwent EUS, with or without ERCP, for suspected choledocholithiasis, ERCP did not identify any new cases of choledocholithiasis following a negative EUS in 21 patients.⁶ In a separate prospective study examining 32 patients with suspected biliary pancreatitis, the sensitivity of US, CT, MRCP, and ERCP for identifying choledocholithiasis was 20%, 40%, 80%, and 90%, respectively.⁹

Nevertheless, choledocholithiasis still occurs in 10% of patients presenting with cholecystectomy.¹⁰ Effective treatment includes both repeat cholecystectomy and clearance of the entire biliary tract. There is evidence that elective and emergent clearance of the bile duct by ERCP has advantages over open bile duct exploration, which is usually combined with open cholecystectomy. In the elective setting, ERCP therapy and laparoscopic bile duct clearance are equivalent for the majority of stones. In a research study conducted from September 21, 1989, to December 31, 2001, 3,580 patients presented with symptomatic biliary tract disease and laparoscopic cholecystectomy was performed in 3,527 patients (99.5%).¹⁰ Of the 3,417 laparoscopic cholangiograms, 344 (9.7%) were abnormal. Laparoscopic common bile duct exploration successfully cleared the duct in 317 of the 344 patients with abnormal cholangiograms (92.2%).

Conclusion

When possible, elective management of choledocholithiasis via the endoscopic approach (ie, ERCP) should be offered. The role for ERCP in the management of acute calculous bile duct disease remains central and optimal. Following successful endoscopic bile duct clearance, most patients should undergo laparoscopic cholecystectomy as early as possible to reduce the risk of a further biliary event or to treat any cholecystitis that may be present. However, for the small group of elderly or frail patients who are considered a high surgical risk for laparoscopic cholecystectomy, judicious conservative management of the in situ gallbladder is justified and acceptable.