Diagnostic and Therapeutic Endoscopy of Biliary Diseases

DISEASES OF THE BILIARY TRACT, SERIES #6 Rad Agrawal, M.D., Series Editor Diagnostic and Therapeutic Endoscopy of Biliary Diseases by Yamini Subbiah, Shyam Thakkar, Elie Aoun The therapeutic approach to biliary diseases has undergone a paradigm shift over the past decade toward minimally invasive endoscopic interventions. This paper reviews the advances and different diagnostic and therapeutic endoscopic approaches to common biliary diseases including choledocholithiasis, benign and malignant biliary strictures and bile leaks. INTRODUCTION endoscopist to differentiate between benign and malig- ith the introduction of innovative endoscopic nant features, thus guiding decision making in real time. implements and options allowing for unprece- Wdented access to the biliary tree, the therapeutic COMMON BILE DUCT STONES approach to biliary diseases has undergone a significant Over 98% of biliary disorders are linked to gallstones. paradigm shift over the past decade toward minimally Stones are found in the common bile duct (CBD) in up invasive endoscopic interventions. The days where bil- to 18% of patients with symptomatic cholelithiasis (1). iary diseases were exclusively managed surgically are The vast majority of gallstones are cholesterol-rich, long gone, and much has changed since the first form in the gallbladder and gain access to the CBD via reported biliary sphincterotomies in 1974. The recent the cystic duct. De novo CBD stone formation is also developments in peroral cholangioscopy and new well described and is more common in patients of modalities of anchoring high resolution nasogastric Asian descent. These primary duct stones typically scopes in the bile duct offer the opportunity of direct have a higher bilirubin and a lower cholesterol content visualization of the bile duct lumen, which allows for and biliary stasis; further, bacterial infections have not only better identification of the underlying disease been implicated in their pathogenesis (2,3). CBD process but also for targeting of biopsies and directed stones can lead to several complications including bil- lithotripsy. Other modalities that add to the growing iary colic, obstructive jaundice and cholangitis. world of biliary luminal imaging include endoscopic ultrasound (EUS) and intraductal ultrasound, which Diagnostic Imaging Tests enable the endoscopist to assess extrabiliary disorders. While a minority of patients with a straight-forward EUS-assisted fine needle aspiration (FNA) tissue sam- clinical presentation consistent with choledocholithia- pling and immediate preliminary histopathologic analy- sis may immediately be treated with ERCP, the vast sis also assist in immediate decision making and majority will benefit from diagnostic imaging studies therapeutics. Other recent advances include cutting- to confirm the diagnosis. Performing a diagnostic edge molecular imaging technology that allows the ERCP with no prior imaging is not optimal due to the potential risks associated with the procedure. Current imaging modalities available for this purpose include Yamini Subbiah, MD; Shyam Thakkar, MD; Elie Aoun, MD, MS, West Penn Allegheny Health System, Divi- transabdominal ultrasound, regular- and high-resolu- sion of Gastroenterology, Hepatology and Nutrition, Pittsburgh, PA. (continued on page 32) 30 PRACTICAL GASTROENTEROLOGY • JULY 2011 Diagnostic and Therapeutic Endoscopy of Biliary Diseases DISEASES OF THE BILIARY TRACT, SERIES #6 (continued from page 30) hCTC remains underused due to its limited availability as compared with MRCP. Over the past few years, the use of EUS as a diagnostic imaging modality for CBD stones has gained significant momentum. While more invasive than the above methods, its associated risks and complications are lower than those with ERCP. The sensitivity and specificity at detecting CBD stones are 95% and 98%, respectively, with a total accuracy of 96% (14,15). Figure 1. Endoscopic ultrasound showing stone in the Furthermore, studies have shown that in cases with common bile duct; B) Gallstone extraction during ERCP. moderate or low clinical suspicion for choledocholithiasis, the use of EUS may prevent up to 30% of unnec- tion computed tomography (CT) scans, magnetic reso- essary ERCPs (16). Figure 1A illustrates an EUS nance cholangiopancreatography (MRCP) and EUS. showing a stone in the CBD. A transabdominal ultrasound remains the initial test of choice in suspected cases of choledocholithiasis because of its wide-spread availability and relatively Endoscopic Therapy lower costs. Dilated ducts seen on ultrasound are Prior to the introduction of ERCP with sphincterotomy highly suggestive of biliary obstruction; however, in the 1970s, choledocholithiasis was mainly managed normal caliber ducts do not exclude a CBD stone. with surgical extraction and open bile duct exploration Furthermore, differentiating between causes of (17). Now, endoscopic techniques are first-line therapy obstruction may also be difficult using this imaging for CBD stones. modality. Even still, while the transabdominal ultra- ERCP should be reserved for patients in whom a sound’s sensitivity in detecting choledocholithiasis is therapeutic intervention is likely to occur. Neverthe- low (ranging between 25% and 58%), its specificity less, in certain rare situations where the diagnosis can be greater than 95% (4–6). remains uncertain despite multiple imaging modalities, MRCP has catapulted to the frontlines of diagnos- ERCP may be required. Once the diagnosis is sus- tic imaging and is typically the next test physicians pected or established, stone extraction and ductal perform following an indeterminate transabdominal clearance become the therapeutic goals. Using a side- ultrasound. Its sensitivity and specificity is 95% and viewing scope which allows direct visualization and 97%, respectively, in detecting the presence and level easy access to the papilla, cannulation of the bile duct of biliary obstruction. However, its sensitivity in detect- can be performed using a variety of available instru- ing stones is a function of stone size. While it ranges ments including cannulas and sphincterotomes. In the from 67%–100% for stones larger than 1 cm, it can be hands of an experienced endoscopist, cannulation suc- as low as 33%–71% in stones less than 6 mm (7–9). cess rates average ~95% (18). Once ductal access is Conventional CT scans have relatively good accu- established, contrast can be used to opacify and visu- racy (70%–94%) when it comes to identifying both the alize the lumen. Typically stones are identified on the presence and the cause of biliary obstruction (10,11). cholangiogram as filling defects around which the con- A newer technique, the helical CT cholangiography trast flows. Opacification of the ducts also allows for (hCTC), is yet another diagnostic option and allows measurement of the severity of the dilation proximal to for three-dimensional reconstitution of images through the stone if any. Frey et al quote the accuracy of ERCP the use of volumetric data after the administration of at detecting CBD stones to be at 96% (19). both oral and intravenous (IV) contrast. It has proven Once the stone is identified, the focus shifts to to be beneficial in detecting CBD stones with a sensi- extracting it from the duct. Figure 1B shows gallstone tivity of ~87% and a high specificity of 97%, account- extraction during ERCP. In the majority of cases, a bil- ing for an overall accuracy of 95% (12,13). However, iary sphincterotomy is needed prior to stone removal. 32 PRACTICAL GASTROENTEROLOGY • JULY 2011 Diagnostic and Therapeutic Endoscopy of Biliary Diseases DISEASES OF THE BILIARY TRACT, SERIES #6 In certain cases where such a cut may be problematic, ERCP pancreatitis. Readmission is more likely to occur such as in patients on anticoagulation, the endoscopist in patients who have one or more of the following risk may elect to balloon dilate the sphincter area. It should factors: suspected sphincter of Oddi dysfunction, cir- be noted though that there are reports of higher risks of rhosis, difficult bile duct cannulation, precut sphinctero- post-ERCP pancreatitis in cases where balloon dilation tomy, or combined percutaneous-endoscopic procedure. has been used (20). In cases where cannulation is diffi- The majority of complications requiring readmission cult to achieve, a needle knife papillotome can be used occur within six hours following the procedure (28). in a technique known as “precutting” to establish direct access into the bile duct. Once access is achieved, a PREVENTING RECURRENCE variety of instruments are available to attempt ductal Recurrent CBD stones occur most frequently in patients clearance. Most stones up to 15 mm in size can be with concurrent choledocholithiasis and cholelithiasis removed by sweeping the ducts with an extraction bal- (29). A study of 371 patients who underwent an ERCP loon, or alternatively by using a Dormia basket pro- with sphincterotomy but who did not undergo subse- vided that a large enough sphincterotomy has been quent cholecystectomy over a span of 7.7 years found a performed (21). In certain instances, though, the stone 10% recurrence rate of choledocholithiasis (30). A size may be too large to extract, and as such, alternative smaller study of 120 patients who had undergone a bil- methods such as lithotripsy should be considered. iary sphincterotomy for CBD stones and who were ran- Different lithotripsy modalities are available domized to laparoscopic cholecystectomy or a “wait including mechanical,

Load more