Researchers describe new methods to collect and process bile duct biopsies for evaluation of strictures, in the September issue of Clinical Gastroenterology and Hepatology. These approaches should provide a greater quantity of material for analysis and increase the accuracy of diagnosis.
A biliary stricture is an abnormal narrowing of the common bile duct—the tube that moves bile from the liver to the small intestine. Strictures can be caused by different factors, including tumors, so effective techniques are needed to visualize them and collect samples.
Endoscopic retrograde cholangiopancreatography (ERCP) it is the standard technology used to evaluate disorders of the biliary tract; it combines endoscopy and fluoroscopy to diagnose and treat problems of the biliary or pancreatic duct systems. A newer technique, cholangioscopy, examines bile ducts using a fiberoptic endoscope, which allows for direct visualization of the biliary tree and collection of specific tissues. The SpyGlass direct visualization system of cholangioscopy allows for a peroral rather than percutaneous transhepatic approach. Some bile duct biopsy samples are shown in the below figure.
Douglas Hartman et al. compared 110 consecutive bile duct specimens collected from 89 patients with indeterminate biliary strictures at the University of Pittsburgh Medical Center using either ERCP or the SpyGlass cholangioscopy system (or in some cases, both). Because these techniques collect ductal biopsy fragments of such small size, special procedures were followed to maximize the amount of tissue for histopathology analysis.
They found that more tissue could be obtained using the standard fluoroscopic-guided than the cholangioscopic-directed procedure. Based on follow-up of the patients, fluoroscopy-guided biopsies assessed indeterminate biliary strictures with 88% accuracy, whereas cholangioscopic-directed biopsies assessed them with 78% accuracy. The SpyGlass technique performed better for analysis of proximal than for distal strictures. The rates of malignant and benign diagnoses were similar between the 2 procedures.
Hartman et al. conclude that standard fluoroscopic-guided and SpyGlass-directed biopsies each provide important information for evaluating biliary strictures, with an overall diagnostic accuracy of 85%.
Their study also provided information on how the diagnostic yield and accuracy of these techniques might be improved. Introduction of special laboratory protocols for handling these small biopsy fragments, acquisition of more biopsy fragments by endoscopists, and development of larger biopsy forceps will reduce the number of insufficient specimens and provide more tissue for pathologists to evaluate.
Hartman et al. propose that as pathologists, pathology laboratories, and endoscopists gain more experience with small biopsies collected by cholangioscopy, diagnostic accuracy will continue to improve.
More Information on Bile Duct Strictures:
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Hartman DJ, Slivka A, Giusto DA, et al. Tissue yield and diagnostic efficacy of fluoroscopic and cholangioscopic techniques to assess indeterminate biliary strictures. Clin Gastroenterol Hepatol 2012;1042−1046.