Do we overestimate the performance of the basket catheter for stone removal if the bile duct is swept with a balloon?

We read with great interest the paper by Ishiwatari et al. published in the April issue of Endoscopy [1]. The authors compared the performance of balloon and basket catheters for the removal of bile duct stones (diameter ≤ 10 mm) during endoscopic retrograde cholangiopancreatography (ERCP) in a multicenter randomized trial. They found that balloon catheter extraction was superior to the basket catheter, especially for the removal of four or more stones. We think the results make an important contribution to the current knowledge as well as to the daily practice of endoscopists. However, there are some points that need to be clarified and discussed further.

After the removal of stones in the basket catheter group, the authors used a balloon catheter to check for duct clearance and residual stones prior to doing a balloon-occluded cholangiography (BOC). This balloon sweep was probably performed to remove any possible filling defect caused by air. However, it is possible that this procedure affected the study results, and further explanation and clarification are required.

A sweep of the bile duct with a balloon catheter is a common practice during ERCP in order to remove any material or debris, such as stones, sludge, parasites, and hydatid membranes. In the current study, this procedure may remove the residual stones and achieve the duct clearance prior to a BOC. The authors did not mention whether any stone was removed during this balloon sweep procedure in the basket catheter group. Moreover, during a balloon sweep, some small stones might be overlooked by the endoscopist owing to position and distance of the scope to the papilla, and the rapid advance of the stones toward the distal duodenum. Therefore, sweeping the duct with a balloon catheter may overestimate the performance of a basket catheter in such a study design, and may represent the success rate of a basket plus balloon catheter instead of a basket catheter alone. The authors concluded that for treatment of fewer than four bile duct stones, the performance of both catheters is similar and both may be used. However, they came to this conclusion with the abovementioned methodological bias. In practice, using both catheters increases the cost of the procedure, and is not warranted as each catheter has a high success rate for stones ≤ 10 mm in diameter.

We think it should be stressed by the authors that use of the balloon in the basket group represented a confounding factor in the study design, and that sweeping the duct with a balloon catheter in the basket group may have potentially affected the study results.

• Reference

• 1 Ishiwatari H, Kawakami H, Hisai H et al. Balloon catheter versus basket catheter for endoscopic bile duct stone extraction: a multicenter randomized trial. Endoscopy 2016; 48: 350-357