Refinement of the positive predictive value of gallbladder nonvisualization after morphine administration for acute cholecystitis based on the temporal pattern of common bile duct activity

The authors previously reported two major patterns in the time-activity cur ve of the common hepatic bile duct (BD) after morphine administration in pa tients with gallbladder nonvisualization. The first pattern consists of a g radual increase in BD activity (of variable duration) occurring during a si multaneous decrease in liver parenchymal activity (BD up arrow), representi ng the physiologic effects of morphine administration. The second pattern c onsists of a continuous decrease in BD activity that parallels the activity in the liver parenchyma (BD down arrow), representing lower or no physiolo gic effects of morphine administration. The authors hypothesize that gallbl adder nonvisualization associated with a continuous decrease in BD activity after morphine administration will have a lower positive predictive value (PPV) for acute cholecystitis than gallbladder nonvisualization associated with an increase in BD activity. Methods: Thirty-six patients who had morphine-augmented cholescintigraphy w ere divided into two groups: 19 with BD up arrow after morphine administrat ion and 17 with BD down arrow. Results: Of the 36 patients, 22 had acute cholecystitis. The positive predi ctive value (PPV) of gallbladder nonvisualization was 61%. All of the remai ning 14 had chronic cholecystitis. Of 19 patients with BD up arrow, 15 had acute cholecystitis (PPV = 79%), whereas only 7 of 17 patients with BD up a rrow (PPV = 41%) had acute cholecystitis (P = 0.023 by the one-tailed and 0 .038 by the two-tailed Fisher exact tests). Conclusions: Gallbladder nonvisualization after morphine administration wit h the pattern of BD down arrow is not as reliable (intermediate probability in this series) for the diagnosis of acute cholecystitis as is nonvisualiz ation of the gallbladder in patients with a pattern of BD up arrow (high pr obability).