Preoperative ultrasonographic assessment of the number and size of gallbladder stones: is it a useful predictor of asymptomatic choledochal lithiasis?

OBJECTIVE: To evaluate whether preoperative ultrasonographic assessment of the number and size of gallbladder stones can identify patients at increased risk of having asymptomatic common bile duct stones.
METHODS: Ultrasonographic data for 300 consecutive patients undergoing laparoscopic cholecystectomy were analyzed. Patients were divided into a group in which multiple small (< or = 5 mm) or multiple variably sized (both < or = 5 and > 5 mm) gallbladder stones were present ("positive" stones) and a group with multiple large (> 5 mm) or single gallbladder stones, considered "negative." The ultrasonographic description was compared with surgical findings; finally, the prevalence of asymptomatic common bile duct stones in the 2 groups was compared.
RESULTS: Ultrasonographic classification of gallbladder stones was confirmed at surgery in 285 cases (95%). Asymptomatic common bile duct stones were diagnosed in 9.5% of patients with an ultrasonographic diagnosis of positive gallbladder stones and in only 2.3% of patients with a diagnosis of negative gallbladder stones (P < .05).
CONCLUSIONS: Ultrasonography is able to accurately show gallbladder stones; the appearance of multiple small and variably sized gallbladder stones represent a risk factor for synchronous asymptomatic common bile duct stones.