Why should a supine position be avoided in ERCP procedures?

The supine position is typically avoided in Endoscopic Retrograde Cholangiopancreatography (ERCP) procedures primarily because it is associated with increased difficulty in cannulating the bile duct. In this position, the anatomical orientation can make access to the duodenum and the papilla more challenging for the endoscopist. The supine position may also obscure the duodenum's natural curves, complicating the navigation of the endoscope toward the ampulla of Vater, where the bile duct opens.

When the patient is positioned in a left lateral decubitus or prone position, it can often enhance visibility and access to the duodenum, facilitating easier cannulation of the biliary tree. This positioning allows for better gravity-assisted flow and alignment of the endoscope's tip with the target structures.

Therefore, the choice to avoid the supine position is directly linked to improving procedural success rates and reducing complications related to difficult cannulation.