How to improve biopsy sampling of bile duct strictures: use small- or large-cup biopsy forceps or imagine another kind of forceps!

We read with interest the article by Ikeda et al. about the use of large-capacity forceps for obtaining tissue in cases with extrahepatic biliary strictures [1]. In this study, the authors compared two different sized biopsy forceps in 32 patients with extrahepatic biliary strictures to determine pathologic diagnostic rate, specimen adequacy, and submucosal tissue sampling rates. They found that biopsies obtained using the large-cup forceps (2.4 mm) yielded a significantly higher diagnostic sensitivity than biopsies obtained using the standard small-cup forceps (1.8 mm). This was particularly true in cases with bile duct cancer (92 % vs. 50 %, respectively). To date, this is the highest rate of diagnosis reported in the literature, where the range is from 43 % to 81 % [2] [3] [4]. Overall, including patients with extrahepatic biliary strictures other than bile duct cancer, Ikeda et al. found that large-cup forceps provided a higher pathologic diagnostic rate (70 % vs. 43 %) and were reported to be much better in adequacy and submucosal tissue sampling than small-cup biopsy forceps [1].

The authors in this article indicated that they obtained tissue specimens with a 100 % success rate [1]. Bile duct cancers can cause complex strictures that often do not allow biopsy forceps to engage the stricture and in some cases even passage of a wire-guided brush is not possible. In those cases we use internal bougienage dilation to facilitate tissue sampling. It is interesting that the authors apparently did not need to dilate the stricture prior to obtaining biopsies. The authors also noted that in 30 cases (94 %) a histologic diagnosis was obtained; 70 % of large-cup and 43 % of small-cup biopsy samples resulted in a specific pathologic diagnosis. We are uncertain as to whether some cases were diagnosed only by small-cup biopsy sampling and some cases only by large-cup biopsy sampling. We believe this clarification is important as small-cup forceps can be much easier to open fully within these strictures and large-cup forceps will not be able to open fully due to luminal distortion/constriction. It is also interesting that in this series 12 patients had biliary strictures due to pancreas cancer, two from gallbladder cancer, two from chronic pancreatitis, two from lymph node metastasis from cancer of other organs, one hepatocellular and one duodenal cancer. The authors state a 56 % pathologic diagnostic rate in large-cup forceps biopsies in these 20 cases. It is difficult to believe that in more than half of cases with secondary cancers the tissue extended into the inner lumen of the bile duct. In these patients with extrinsic biliary pathologies and bile duct strictures, we prefer to use other methods to obtain tissue such as endosonography (EUS)- and computed tomography-guided biopsies. This is in spite of the fact that the diagnostic sensitivity of EUS-guided biopsies for extrahepatic bile duct cancers is as low as 45 % [5].

In the present article, two cases were diagnosed based on clinical course without histology. Absence of histopathologic diagnosis in these patients results in miscalculation of diagnostic and tissue adequacy rate obtained by forceps biopsies. The authors also did not mention whether or not the pathologist was blinded to the sampling method. Another flaw in the present study is that the order of biopsy forceps used was determined randomly using sealed envelopes. However, the number of first biopsies taken by the small-cup biopsy forceps is not mentioned. This is important because if most of the first two biopsies taken were with small-cup forceps then the submucosal tissue sampling rate would be lower. In fact, this may have allowed deeper tissue sampling from the subsequent large-cup forceps.

Another problem is that biliary forceps tissue sampling is technically demanding and time-consuming even for the most experienced endoscopists. To overcome this, we use an introducer device for wire-guided biopsy forceps (Cook Endoscopy, Winston-Salem, North Carolina, USA) or a new wire-guided forceps (MTW Endoscopy, Wesel, Germany), which has a design similar to a sphincterotome. A handle allows tension to be applied to a wire that causes the tip of the biopsy forceps to curve in an upward direction into the papillary orifice and toward the bile duct, which facilitates biliary cannulation. However, the cost of this device is much higher than standard biopsy forceps, but is helpful in cases where biliary access is difficult.

References

• 1 Ikeda M, Maetani I, Terada K et al. Usefulness of endoscopic retrograde biliary biopsy using large-capacity forceps for extrahepatic biliary strictures: a prospective randomized study.  Endoscopy. 2010;  42 837-841
• 2 Ponchon T, Gagnon P, Berger F. Value of endobiliary brush cytology and biopsies for the diagnosis of malignant bile duct stenosis: results of a prospective study.  Gastrointest Endosc. 1995;  42 565-572
• 3 Pugliese V, Conio M, Nicolò G et al. Endoscopic retrograde forceps biopsy and brush cytology of biliary strictures: a prospective study.  Gastrointest Endosc. 1995;  42 520-526
• 4 Kubota Y, Takaoka M, Tani K et al. Endoscopic transpapillary biopsy for diagnosis of patients with pancreaticobiliary ductal strictures.  Am J Gastroenterol. 1993;  88 1700-1704
• 5 Byrne M F, Gerke H, Mitchell R M et al. Yield of endoscopic ultrasound-guided fine-needle aspiration of bile duct lesions.  Endoscopy. 2004;  36 715-719