Review Article
Role of endoscopic evaluation in idiopathic pancreatitis: a systematic review

https://doi.org/10.1016/j.gie.2006.02.024Get rights and content

In approximately 20% of patients with acute pancreatitis, a cause is not established by history, physical examination, routine laboratory testing, and abdominal imaging. For those with a single unexplained attack, the role of invasive evaluation with endoscopic retrograde cholangiopancreatography is unsettled but has been generally limited to those patients with suspected bile duct stones or malignancy. Recent studies suggest that microlithiasis is causative in up to 75% of patients with an unexplained attack and gallbladder in situ, whereas sphincter of Oddi dysfunction is most prevalent in those with recurrent attacks who have previously undergone cholecystectomy. EUS has been shown to be highly accurate for the identification of gallbladder sludge, common bile duct stones, and pancreatic diseases. Given this apparent diagnostic utility, an EUS-based strategy may be a reasonable approach to evaluate patients with a single idiopathic attack. ERCP and sphincter of Oddi manometry should generally be reserved for patients with multiple unexplained attacks and negative EUS results, especially for those patients who have previously undergone cholecystectomy.

Section snippets

Methods

Our systematic review was conducted according to previously proposed criteria.22 We searched PubMed (1966–January 1, 2006; English language) using the search terms “idiopathic pancreatitis, unexplained pancreatitis, and recurrent pancreatitis.” We also searched using the term “genetic testing in idiopathic pancreatitis.” We retrieved potentially relevant articles and reviewed their reference list to identify studies that our search strategy may have missed. We also searched our personal

Defining idiopathic pancreatitis

There are no agreed-on criteria for what constitutes an appropriate evaluation before an attack is labeled as being idiopathic. Generally, an attack is considered idiopathic after history, physical examination, laboratory studies, and US and CT imaging reveal no cause. Intuitively, the prevalence of idiopathic pancreatitis will necessarily depend on the epidemiologic setting, the criteria used to define specific causes, and the extent of the diagnostic evaluation. Nevertheless, for unclear

Role of microlithiasis

Although gallstones have been recognized as a cause of acute pancreatitis for about a century, only recently have biliary sludge and microlithiasis been linked to acute biliary pancreatitis.27, 28, 29, 30 Microlithiasis is often referred to as small stones less than 3 mm in diameter.27, 28, 30, 31 Biliary sludge is defined as a suspension of crystals (usually cholesterol monohydrate), mucin, glycoproteins, cellular debris, and proteinaceous material within bile.16 Sludge may be visualized by

ERCP

As noted above, current practice has traditionally been to more aggressively evaluate patients after multiple attacks rather than after the first idiopathic attack, presumably because of the inherent complications of ERCP.23, 24 However, to our knowledge, there have been only 2 studies, only one of which was prospective, whose primary focus was evaluating such a cohort, and in only one was follow-up reported. In the earliest study, Ballinger et al52 retrospectively identified 31 patients with

ERCP

Studies performed early on after the birth of ERCP suggested a potential role for pancreatography in patients with idiopathic pancreatitis,56 and a number of centers worldwide have now reported their experience with ERCP in RIP10, 53, 54, 55, 59, 60, 61, 62, 63, 64 (Table 2). Many of the initial studies are flawed by the inclusion of patients with only a single attack11, 54 or inclusion of those with gallbladder stones55 and outdated by the technologic infancy of US and CT and by failure of

Recommendations for evaluation

The majority of patients with acute pancreatitis will have a diagnosis established with use of routine investigations. Recent studies with EUS used after conventional evaluation underscore that the true prevalence of idiopathic pancreatitis depends on the extensiveness of the evaluation. Long-term follow-up has not been commonly performed in most studies and, thus, the true importance of some causes, on the basis of the recurrence of pancreatitis, remains less well defined.

On the basis of the

Areas for future investigation

The data presented above clearly demonstrate the importance of biliary sludge in the genesis of idiopathic pancreatitis. Although duodenal sampling for crystal analysis and EUS have shown promise, additional studies are warranted to determine whether initial EUS and, if results are negative, microscopic examination of bile for crystals is the appropriate diagnostic strategy. Additional studies are also warranted to better determine the ideal method for microscopic examination of bile for

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