Gallstone Size and Risk of Pancreatitis


Synopsis: Patients with acute pancreatitis were more likely to have at least one gallstone smaller than 5 mm, 20 or more stones, a mulberry-shaped stone, and lower gallstone weight than those with uncomplicated pain.

Source: Diehl, et al. Arch Intern Med 1997;157:1674-1678.

Diehl and colleagues studied a total of 551 patients, 398 of whom were Mexican-American. They had detailed pathologic and clinical data including whether the patients had uncomplicated pain or acute pancreatitis, and the size, number, and shape of the stones. By performing a univariate and logistic regression analysis and then comparing the data to the socio-demographic data, they are able to come up with results that have clinical applicability. Those patients with acute pancreatitis are more likely to have one gallstone smaller than 5 mm in diameter, 20 or more gallstones, mulberry-shaped gallstones, or a lower total gallstone weight than patients who have uncomplicated pain. They looked at patient age, gender, ethnic or racial back ground, educational attainments, smoking habits, alcohol use, body mass index, parity, co-existing diabetes, and cirrhosis. They did not find any of these parameters to have any effect on pancreatitis with gallstones. Most interestingly, they found a four-fold increased risk of presentation with acute biliary pancreatitis in patients who had a gallstone smaller than 5 mm in diameter.


The number of cholecystectomies in the United States has dramatically increased to 500,000 a year, especially since 1991 when the laparoscopic approach became popular. Most clinicians watched "silent" gallstones found on ultrasound, but those patients who have symptomatic gallstones were harder to figure out. Some believe that they should have an immediate cholecystectomy, yet recent guidelines state that at the first episode of pain, the patient may choose to observe "the pattern" before deciding about surgery. These guidelines come from no less an authority than the American College of Physicians.

Wouldn’t it be great if we could figure out which patients should not observe their pattern or should have a cholecystectomy? Unfortunately, before this study, there has been meager research done to identify those patient characteristics.

By looking at the patients with gallstones and knowing their clinical and socio-demographic histories, Diehl et al were able to find out that those patients with gallstones smaller than 5 mm in diameter have four times the risk of acute biliary pancreatitis. This is near revolutionary. Smaller is worse. I imagine that we will see more routine estimations of gallstone size on imaging studies from our radiologic colleagues.

The authors also found, although it was buried in the article, that there is approximately a 1% annual incidence of pancreatitis among patients with gallstones. It makes it hard to watch the patients.

I, for one, am going to review the scans on patients who have gallstones to find out if any of them have a small gallstone, less than 5 mm in diameter. If so, I’ll warn the patient, and perhaps we’ll be moving into more laparoscopic surgery. If my patients have multiple gallstones, less than 20, and all of them are larger than 5 mm in diameter, I might tell them that waiting will put them at risk for a 1% incidence of pancreatitis.