To prospectively determine the range of abdominopelvic ultrasonographic findings, including Doppler resistance index (RI) of uterine arteries, 2 and 24hours after uncomplicated delivery.

Women who delivered vaginally or after cesarean section without complication from January 2012 to April 2012 in a tertiary care hospital were prospectively included. Abdominopelvic ultrasonography, including uterine artery resistance index (RI) at duplex Doppler ultrasonography, was performed 2hours and 24hours after delivery.

Ninety-two women (mean age, 32.7 years) were included. Sixty-one (66%) delivered vaginally and 31 (34%) had cesarean section. Twenty-four hours after vaginal delivery, endometrial and anterior wall thicknesses dropped and uterine width increased (P<0.001). No changes in uterine length and posterior wall thickness were observed between 2 and 24hours after delivery. Transient pelvic free-fluid effusion was observed in 1/92 woman (1%). Uterine artery RI increased significantly from 2 to 24hours (0.50 vs 0.57, respectively; P<0.001).

Pelvic free-fluid effusion is exceedingly rare in the early course of uncomplicated delivery. A significant increase in uterine artery RI during the 24hours following uncomplicated delivery is a normal finding. It can be anticipated that familiarity with these findings would result in more confident diagnosis of complications.