Variation in the estimation of gallbladder volume using the sum-of-cylinders method.

RATIONALE AND OBJECTIVES

Gallbladder contraction was measured by ultrasound, using the sum-of-cylinders method, as part of a study of the effects of lipid-lowering drugs. Although this method of measurement has been validated in the literature, paired measurements were obtained to provide an additional check on reproducibility.

METHODS

A total of 136 pairs of gallbladder measurements were made on 17 patients using the sum-of-cylinders method of calculating gallbladder volume. Each pair comprised a left posterior oblique and a supine measurement performed at the same ultrasound examination to assess measurement error.

RESULTS

There was a large average coefficient of variation of 21%.

CONCLUSIONS

Marked measurement variability limited the ability of the sum-of-cylinders technique to detect even modest alterations in gallbladder contractility, at least in this population subgroup.