Roscoe Miller award. Fatty-meal sonography for evaluating patients with suspected partial common duct obstruction

We evaluated the efficacy of fatty-meal sonography for identifying patients with partial common duct obstruction. The test consisted of initial control measurements of common duct diameter followed by repeated measurements every 15 min for 60 min after a fatty meal consisting of Lipomul (1.5 ml/lb). The rationale proposed for the fatty-meal test is that in the presence of partial common duct obstruction, fat-induced increases in bile flow related to increased circulating levels of cholecystokinin are associated with an increase in the diameter of the common duct. Initial analysis of our data indicated that a change in diameter of +/- 1 mm was within the range of measurement error or possibly physiologic variation. In 44 control subjects (24 without a gallbladder), the common duct diameter either remained unchanged, showed an insignificant change of +/- 1 mm, or decreased (greater than or equal to 2 mm). The common duct diameter never showed an increase of more than 1 mm. The results of fatty-meal sonography in 47 patients with suspected partial common duct obstruction were negative in all 28 true-negative cases (specificity, 100%) and were positive (common duct increased by greater than or equal to 2 mm) in 14 of 19 true-positive cases (sensitivity, 74%). Thus, in this study a positive test finding always indicated partial common duct obstruction. Of the true-positive cases, fatty-meal sonography correctly identified seven of eight patients with cryptic obstructive sphincter-of-Oddi dysfunction (stenosis or dyskinesia) and five of nine patients with commun duct stones. We conclude that fatty-meal sonography is a useful noninvasive screening test for evaluating patients with suspected partial common duct obstruction.