The value of hepatobiliary scans in fasted patients receiving total parenteral nutrition

Hepatobiliary scanning is considered to be a highly accurate method for the diagnosis of acute cholecystitis. False-positive scans (failure to visualize the gallbladder in the absence of cholecystitis) have been reported to occur in fasted patients receiving total parenteral nutrition (TPN). To determine the prevalence of false-positive scans in this patient population and identify factors that might be associated with scan outcome, hepatobiliary imaging was performed in fasted patients receiving TPN and without clinical evidence of acute cholecystitis. Gallbladder nonvisualization occurred in 18 of 50 (36%) patients. In the group whose gallbladders did not visualize, a significantly higher male to female ratio (15:3 versus 17:15; p = 0.016), alkaline phosphatase (346 +/- 84 IU/L versus 212 +/- 32 IU/L, p less than 0.04), total bilirubin (1.7 +/- 0.3 mg/dl versus 1.0 +/- 0.2 mg/dl, p less than 0.02), and lower serum albumin (2.4 +/- 0.01 gm/dl versus 2.8 +/- 0.2 gm/dl, p less than 0.02) levels were noted. In 18 patients, gallbladder ultrasonography was also performed, and the presence of sludge or a thickened gallbladder wall did not correlate with scan outcome. The prevalence of false-positive hepatobiliary scans in fasted patients receiving TPN is significant and does not always correlate with a syndrome of acute gallbladder inflammation. The results of such scans must therefore be interpreted with caution in these patients.