Preoperative assessment of bile duct stones with sonography

(Ultrasound Review) Surgeons at Parma University School of Medicine have shown that ultrasound can accurately predict the likelihood of asymptomatic common bile duct stones (CBDS) in patients with gallbladder stones.

The patient was considered to have small gallstones when some or all of the calculi measured 5mm or less. They analyzed the prevalence of asymptomatic common bile duct stones in patients with and without small gallbladder calculi.

"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," they discovered. Their research was published in the Journal of Ultrasound in Medicine.

Three hundred patients were scanned prior to surgery. Results demonstrated that ultrasound correctly showed the size and number of gallstones in 95% of patients. There were two reasons for an inaccurate sonographic description of gallbladder size in 15 cases. Either multiple variable sized stones were thought only to be large stones or acoustic shadowing, caused by a single large stone prevented, visualization of smaller stones.

They reported a four times increased risk for CBDS in patients with gallbladder calculi found at ultrasound compared with patients with a negative ultrasound. Although the specificity (44.8%) and accuracy (47.3%) were low, the high sensitivity (84.2%) suggests that ultrasound should be included as part of the preoperative work-up for patients undergoing laparoscopic cholecystectomy, they said.

Results showed that less than half of the patients with CBDS were asymptomatic, but using their criteria only 15.8% of patients with CBDS would be left untreated. They recommend that "in the case of negative stones (and no CBDS or common bile duct dilatation) on ultrasonography, no other investigation of the common bile duct should be performed."

The authors concluded "the ultrasonographic evidence of small or multiple variably sized gallbladder stones represents a risk factor for synchronous asymptomatic CBDS." When ultrasound demonstrates small or multiple gallbladder calculi, and a dilated common duct before surgery, they strongly advise that radiologists use their scoring system to assist with surgical planning.

Preoperative ultrasonographic assessment of the number and size of gallbladder stones: is it a useful predictor of asymptomatic choledochal lithiasis?
Costi, R et al.
Istituto Clinica Chirurgia Generale e Terapia Chirurgica, Parma, Italy.

By Ultrasound Review
November 7, 2002

Copyright © 2002

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