We used real-time ultrasonography to study gallbladder kinetics in 11 nonpregnant women, 17 women using steroid contraceptives, and 33 pregnant women. Gallbladder volume was determined after an overnight fast and serially for 90 minutes after a standard liquid meal. After the first trimester of pregnancy, gallbladder volume during fasting and residual volume after contraction were twice as large as in control subjects. The rate of emptying and the percentage emptied were reduced. In early pregnancy the only important abnormality was a 30 per cent decrease in emptying rate. Gallbladder function was not affected by contraceptive steroids. Incomplete empyting of the gallbladder in late pregnancy leaves a large residual volume and may cause retention of cholesterol crystals, a prerequisite for cholesterol-gallstone formation. These findings are consistent with the view that pregnancy increases the risk of cholesterol gallstones. The increased incidence of gallstones associated with contraceptive steroids does not involve abnormal gallbladder kinetics.
PIP: Pregnancy has been known to increase the risk of developing cholesterol cholelithiasis in women of childbearing age. This study describes the use of real-time ultrasonography in measuring gallbladder function and in determining the effect of pregnancy and contraceptive steroids in gallstone formation. 61 healthy, young, premenopausal, nonobese women participated in the study: 11 were nonpregnant controls; 17 were taking contraceptive steroids; and 33 were 9-37 weeks pregnant. The subjects had an overnight fast and were given a standard liquid test meal the next day. Gallbladder volume during fasting and residual volume after contraction were twice as large in women in their first trimester of pregnancy as in controls. A reduction in the rate of emptying and percentage emptied was observed. A 30% decrease in emptying rate was observed during early pregnancy. Contraceptive steroids did not affect gallbladder function. In later pregnancy, incomplete emptying of the gallbladder may lead to the retention of cholesterol crystals, a precursor of cholesterol-gallstone formation.