From the AGA Journals

Bile Duct Stones: Adequate Dilation Time Cuts Pancreatitis Risk

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Choosing EPBD Over ES

Endoscopic papillary balloon dilation (EPBD) using small diameter balloons (less than 10 mm) as an alterative to endoscopic sphincterotomy (ES) for removal of small bile duct stones is not new. Potential advantages of EPBD over ES are avoidance of bleeding and perforation while preserving biliary sphincter function. Potential disadvantages are potential for post-ERCP pancreatitis (PEP) and recurrence of choledocholithiasis, particularly in patients with an intact gallbladder.

Data on EPBD has been accrued from Asian populations, where the short-term and long-term outcomes are favorable, though with a significantly higher but acceptable risk of PEP. Unfortunately, the one randomized study from the U.S. was stopped prematurely due to two deaths from PEP. This has led to divergence in acceptance of EPBD between endoscopists in the East and West leading to the need for ways to reduce PEP after EPBD, including varying the duration of balloon inflation. In the present meta-analysis by Dr. Liao and his colleagues, longer duration of balloon dilation was found to be associated with less PEP than shorter duration. This finding may seem counterintuitive as longer duration would be expected to lead increased edema and obstruction of the pancreatic duct.

One factor not considered was the rapidity of dilation from zero pressure to the maximum. I believe this factor may be more important than duration since it influences shearing stress and force, tearing of tissue and subsequent peripapillary edema. Could it be that rapid inflation was more common when shorter-duration of inflation was performed? In short, the findings of Dr. Liao and his associates might influence the technique of EPBD in the East, but a more important question might be will these findings increase acceptance of EPBD in the West? Perhaps, but other ways to prevent PEP after EPBD, including the use of pancreatic duct stents and rectally administered non-steroidal anti-inflammatory agents, are more likely.

Todd Baron, M.D., is a professor of medicine and director of pancreaticobiliary endoscopy at the Mayo Clinic, Rochester, Minn. He has no relevant disclosures.



When treating choledocholithiasis, a shorter duration of endoscopic papillary balloon dilation increases, rather than decreases, the risk of postprocedure pancreatitis, reported Dr. Wei-Chih Liao and his colleagues in Clinical Gastroenterology and Hepatology.

"This meta-analysis contradicts the common belief that pancreatitis results from direct pancreatic duct compression during balloon dilation, and thus dilation duration should be short," he and his colleagues wrote. On the contrary, "[endoscopic papillary balloon dilation] with an adequate duration (around 5 minutes) has lower complication rates than the current standard of endoscopic sphincterotomy, and may be used as the first-line treatment for bile duct stones."

Dr. Liao, of the National Taiwan University College of Medicine, Taipei, conducted a systematic review of Medline, the Cochrane databases, and to identify randomized controlled trials of endoscopic papillary balloon dilation (EPBD), endoscopic sphincteroplasty, endoscopic balloon sphincter dilation, and endoscopic balloon dilation. Studies were excluded if dilation duration was not clearly reported.

Overall, 12 studies were included in the analysis: 11 compared EPBD with endoscopic sphincterotomy (EST); 4 compared short-duration EPBD (1 minute or less) with EST; and 7 looked at long-duration EPBD (more than 1 minute) versus EST.

Only one study compared long-duration EPBD with short-duration EPBD, they wrote (Clin. Gastroenterol. Hepatol. 2012 [doi: 10.1016/j.cgh.2012.05.017]).

First, the authors looked at the risk of pancreatitis when comparing EST to short-duration EPBD. They found that the latter had a significantly higher pancreatitis risk, with a pooled odds ratio of 3.87 for developing pancreatitis post procedure, compared with EST (95% confidence interval, 1.08-13.84).

However, long-duration EPBD did not pose a significantly higher risk compared with EST (OR, 1.14; 95% CI, 0.56-2.35).

Similarly, looking at overall complications, the researchers noted a trend toward a higher overall complication rate in short-duration EPBD compared with EST (OR, 1.71; 95% CI, 0.67-4.35). "By contrast, long EPBD seemed to have a lower overall complication rate (pooled OR, 0.61; 95% CI, 0.36-1.04)," wrote the authors.

The researchers also calculated the regression coefficient of dilation duration, and found it to be –0.69, "meaning that every 1-minute increase in dilation duration up to 3 minutes was associated with a 49.8% (95% CI, –9.4% –77.0%) reduction in OR," they wrote.

The finding was similar for overall complications, with every 1-minute increase in dilation duration up to 5 minutes associated with a 45.1% reduction in OR.

In an attempt to explain the findings, Dr. Liao noted that recent evidence suggests that EPBD with dilation duration of 1 minute or less "carries a higher risk of inadequate sphincter loosening, which increases the risks of pancreatitis and failed stone extraction."

"An inadequately loosened sphincter from short-duration EPBD may limit volume expansion of its encircled contents as in a compartment syndrome, thus [worsening] compression of the pancreatic duct from post-EPBD edema and [increasing] pancreatitis risk."

The researchers added that the longest reported EPBD duration is 5 minutes.

"It is unknown whether dilation duration longer than 5 minutes may further reduce pancreatitis risk, but the degree of sphincter loosening can only increase to a certain point. ... Further studies on EPBD with different durations will be helpful to corroborate our findings and determine the optimal duration."

The study was funded by grants from the Royal Society, London; the National Science Council, Taiwan; and the National Taiwan University Hospital, Taipei. The authors stated that they had no individual conflicts to disclose.

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