To the Editor Dr Sheffield and colleagues1 found that on a patient level, intraoperative cholangiography was associated with reduced risk of common bile duct injury during cholecystectomy, presumably by laying out a roadmap for the surgeon. This is consistent with other appropriately powered studies of the topic. A secondary, instrumental variable analysis was performed to control for the unmeasured confounding in this study based on administrative data, but it is unclear whether this was appropriate.
Flum DR. Intraoperative Cholangiography During Cholecystectomy. JAMA. 2013;310(24):2672-2673. doi:10.1001/jama.2013.282648