Using the Pancreas for Common Bile Duct Cannulation?

Selective opacification and deep cannulation of the bile ducts is one of the most difficult features of therapeutic biliary endocopy. ”Random” opacification with a catheter in the common duct has a diagnostic yield of approximately 70 % with pancreatography and 30 % with cholangiography, and represents a typical problem for beginners in endoscopic retrograde cholangiopancreatography (ERCP). Selective cannulation of the common bile duct (CBD) depends on finding the orifice and the correct axis at the correct level. It is widely accepted that selective CBD cannulation should be successful in at least 95 % of the cases for senior endoscopists. There are some rules, based on a knowledge of detailed papillary anatomy, that may help standardize the technique of biliary cannulation. The roof of the orifice has to be approached from below and slightly from the right. Thereafter, the catheter has to go from the left to the right to follow the ”frontal” anatomy of the distal CBD, before coming back to the initial position (Figures [1]- [3]). In this approach, expert endoscopists are not only following the anatomy but following changes induced in the ductal anatomy due to catheter pressure. In some cases, such as peridiverticular papillas, or after Billroth I gastrectomy, the prepapillary segment of the CBD may be distorted, and the maneuvers are more difficult. It was for these particular indications that we described the use of a guide wire inserted into the pancreas to facilitate biliary cannulation [1] by straightening of the papillary region.

Figure 1 Technique of CBD cannulation. The catheter is inserted at 11 o'clock, tangentially to the papilla to get an opacification.

Figure 2 The side wheel is turned left and the endoscope slightly pulled back to follow the anatomy.

Figure 3 The side wheel is turned back to the right and the catheter pushed into the bile duct.

In the current issue of Endoscopy [2], Maeda et al. describe preinsertion of a guide wire into the pancreatic duct in every ”difficult” case of biliary cannulation, defined as failure to introduce the catheter after attempting to do so for 10 min, and they report a significantly higher success rate using this method (93 % vs. 58 %). This suggests that the guide wire may straighten the distal shape of the papillary region and help cannulation. Other experts recommend immediately using a guide wire to enter the bile duct in order to avoid pressure on the papilla with a catheter, but this technique has never been formally evaluated in comparison with the classic insertion of a catheter.

However, these data are not sufficient to allow recommendation of the extended use of pancreatic guide-wire insertion to facilitate biliary cannulation, for the following reasons:

The authors did not succeed in cannulating the bile duct within 10 min in 53 of 107 cases and, when persisting without pancreatic wire insertion, they again failed in 11 of 26 cases. This provides a global success rate for cannulation using the standard technique that is below 80 %, clearly inadequate for experienced endoscopists. They carried out direct pancreatic opacification and then inserted a guide wire using a single-lumen catheter. This is associated with a risk of overinjection (of air and contrast medium) into the pancreatic ducts, with possible acinarization, which is a recognized major risk factor for pancreatitis in most of published series 3 4 5. They report significant hyperamylasemia in the group benefiting from pancreatic guide-wire insertion, with no incidence of acute pancreatitis. These data are not sufficient to claim that the risk of pancreatitis will not be increased, a) because of the small numbers of patients in the report; b) because of the very low rate of therapeutic procedures (only 43 of 107 patients), which are mainly associated with an increased risk of pancreatitis; and c) because of the use of confounding medications such as isosorbide dinitrate (which may reduce the incidence of acute pancreatitis associated with diagnostic ERCP) 6 and urinostatin.

Pancreatitis is the most common and the most severe complication of ERCP. Difficult biliary cannulation is a factor associated with the risk of pancreatitis [3], and facilitating deep CBD cannulation might then reduce the risk of complication. However, placing a guide wire in the pancreas is associated with pancreatic duct opacification and possible acinarization, which are both factors associated with the occurrence of post-ERCP pancreatitis [3] [4] [5] [7]. I would therefore be extremely cautious and reluctant about recommending any manipulation of a normal pancreatic duct in order to facilitate bile duct cannulation, especially in inexperienced hands and in cases in which the therapeutic impact is limited, as in the study by Maeda et al. [2]. The only manipulation that can be justified is transient placement of a pancreatic stent in order to prevent acute pancreatitis in patients who are at very high risk of pancreatitis and are undergoing biliary sphincterotomy due to sphincter of Oddi dysfunction [8].

Using any available trick is rarely a good solution in the absence of proper expertise in ERCP, and the use of the precut technique is another example of the same type. While it seems to be safe and extremely effective in the hands of very experienced endoscopists [9] [10], it frequently appears to be one of the most common independent factors affecting the incidence of pancreatitis in large multicenter studies [4] [5], in which levels of expertise are more variable. The precut technique can, however, be justified when the therapeutic indication is clear and after appropriate instruction to senior endoscopists who already have extensive technical knowledge of ERCP.

Finally, the best method of avoiding complications or failure of ERCP is to limit the number of indications; in the era of magnetic resonance cholangiopancreatography and endoscopic ultrasonography, the proportion of diagnostic ERCPs should undoubtedly be less than one-third of the examinations, even in nonreferral centers.

References

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• 2 Maeda S, Hayashi H, Hosokawa O. et al . Prospective randomized pilot trial of selective biliary cannulation using pancreatic guide-wire placement.  Endoscopy. 2003;  35 721-724
• 3 Freeman M L, Di Sario J A, Nelson D B. et al . Risk factors for post-ERCP pancreatitis: a prospective, multicenter study.  Gastrointest Endosc. 2001;  54 425-434
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• 6 Sundhindran S, Bromwich E, Edwards P R. Prospective randomized double-blind placebo-controlled trial of glyceryl trinitrate in ERCP-induced pancreatitis.  Br J Surg. 2001;  88 1178-1182
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