Randomized Controlled Trial of Short Versus Long Wire and Small Versus Standard Sphincterotomes for Initial Biliary Cannulation

1.0 BACKGROUND

Bile duct access is the most difficult part of endoscopic retrograde cholangiography (ERCP) performed for the biliary indications of bile duct stones, leak, and stricture. In the past decade there has been an evolution in the technology and approach used to achieve selective biliary cannulation, In the classic approach a standard cannula is placed into the biliary orifice and contrast injected to confirm placement. Subsequently, a long wire is passed by the assistant deeply into the duct and the cannulatome exchange for a sphincterotome which is used to perform papillotomy.

The first major change in cannulation approach has been the widespread use of the sphincterotome to obtain initial biliary access in lieu of the cannulatome. This is in part driven by economics. With the advent of endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP) almost all ERCP is therapeutic and sphincterotomy is typically part of this approach.1 Thus it is sensible to forgo the step of using the cannulatome which enables only diagnostic ERCP. In addition to cutting, the wire on the distal tip of the sphincterotome enables variable flexion in the direction of the bile duct, a feature lacking for the cannulatome.

Additionally, high quality comparison trials suggest that the sphincterotome is superior to the cannulatome for initial access. Schwacha et al prospectively randomized patients to bile duct cannulation with the standard cannulatome versus the sphincterotome.2 After five attempts bile duct access was achieved in 62% of those in the standard catheter group compared to 84% in the sphincterotome group. Cortus et al randomized patients to <15 attempts to access with bile duct with the cannulatome versus the sphincterotome and found that initial biliary access was obtained in 67% in the former versus 97% in the latter groups.3 In addition the mean number of cannulation attempts and time to achieve selective biliary cannulation was also less in the sphincterotome group. Given these considerations most American endoscopists use sphincterotomes for initial biliary cannulation.4

Most modern sphincterotomes have two to three lumens to enable simulatenous passage of contrast and wire into the bile duct. Traditionally, contrast was first injected to confirm that the bile duct as opposed to the pancreatic duct had been accessed. In 2004 Lella randomized 400 patients to the standard approach of contrast injection versus the passage of the guidewire to confirm bile duct cannulation.5 In the contrast group 4% of patients developed pancreatitis compared to none in the wire guided group and high pancreatic enzyme levels (5 times the upper limit of normal) developed in 20% of contrast guided versus 5% of wire guided cases. Subsequent large randomized trials have consistently demonstrated post ERCP pancreatitis rates of 2-9% in wire guided versus 10-17% in contrast guided ERCP.6-7 Wire guided cannulation has also been shown to shorten cannulation and fluoroscopy times.8