What is the Best Way to Assess Bile Duct Strictures?

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.

Bile duct biopsy sections, stained with H&E (100×). Panel A shows a biopsy sample that is insufficient for analysis, composed entirely of blood and fibrin, with no tissue or detached epithelial cells. Panel B shows an adequate bile duct biopsy of benign tissue, with a denuded luminal surface (toward the top of image), detached epithelial cells (*), and a cluster of peribiliary glands within the stromal tissue (arrow). Panel C shows a bile duct biopsy of benign tissue, with a denuded luminal surface (toward the top-right of image) and detached epithelial cells (*); even though no peribiliary glands are present, this sample is adequate for analysis. Panel D shows a biopsy of malignant tissue, with a partially intact luminal surface and 2 strips of benign surface epithelium (*), but infiltration of the stroma by malignant glands (indicated by the arrows); even though no peribiliary glands are present, the malignancy can be identified.

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:

Read the article online.
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.

About Kristine Novak, PhD, Science Editor

Dr. Kristine Novak is the science editor for Gastroenterology and Clinical Gastroenterology and Hepatology, both published by the American Gastroenterological Association. She has worked as an editor at biomedical research journals and as a science writer for more than 12 years, covering advances in gastroenterology, hepatology, cancer, immunology, biotechnology, molecular genetics, and clinical trials. She has a PhD in cell biology and an interest in all areas of medical research.
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