The incidence and outcome of pregnancy-related biliary sludge/stones and potential risk factors

Diseases of the gall bladder have been reported to be the most common cause for non-obstetrical hospitalizations during the first year postpartum. Therefore we designed a prospective study to evaluate the incidence and natural outcome of pregnancy-related biliary sludge and stones, and to define the potential risk factors in a population of pregnant women in Sari, Iran.

A total of 380 pregnant women were scheduled for three ultrasound assessments: 1) during the first trimester of pregnancy (9 - 12 weeks),   2) during the early third trimester (26 - 32 weeks), and 3) during the fourth to sixth weeks postpartum. The incidence of biliary sludge, new stones and progression from sludge to stones in addition to the probable risk factors were analyzed with the t-test and chi-square test as appropriate (SPSS software, version 15).

According to the first ultrasonography, 14 (3.7%) participants had evidence of biliary sludge and 3 (0.7%) had gallstones. Among those with normal baseline ultrasound findings, 28 (7.7%) developed biliary sludge and 7 (1.9%) formed stones by their second ultrasound examination (P < 0.05). Among the 14 participants with biliary sludge in their first ultrasound assessment, 1 (7.1%) developed gall stone and sludge remained in the other 13 as seen on the third trimester ultrasound results. According to the third ultrasound (performed postpartum), out of 41 participants with prior biliary sludge, 16 (39%) had no evidence of sludge, 22 (53.7%) had persistent sludge, and 3 (7.3%) developed stones. Out of 11 participants with prior gallstones, 1 had a normal ultrasound postpartum, but stones persisted in the other 10 (P < 0.05). In those with stones, 9.1% underwent cholecystectomies postpartum. The incidence of sludge and stones significantly correlated with the number of pregnancies and higher age at pregnancy.

Since the annual rate of pregnancy is high in Iran, pregnancy-related biliary disorders are important in this country. According to our results, the number of parities and age at pregnancy are potentially modifiable risk factors for lowering pregnancy-related biliary disorders.