Ultrasound examination of the postpartum uterus: what is normal?

Objective: To establish normal ultrasonographic findings for the postpartum uterus after vaginal delivery, and to characterize associated bleeding patterns.Methods: Postpartum women were scanned by transabdominal ultrasound within 48 h after normal vaginal delivery. Uterine length, uterine width, endometrial stripe thickness and endometrial contents were evaluated by a single sonographer. Patients maintained a daily symptom diary for 6 weeks and were interviewed by telephone at 2 weeks. Statistical analysis was performed using χ2, Fisher's exact test, Student's t test and Pearson correlation.Results: Mean endometrial stripe thickness was 1.1±0.6 cm, mean uterine length was 16.1±1.7 cm and mean uterine width was 8.7±1.0 cm. Postpartum bleeding requiring more than four protective pads per day for ≥10 days was associated with a thicker endometrial stripe (1.5±0.7 cm vs. 0.9±0.4 cm, p=0.006). However, no patients experienced postpartum bleeding complications requiring intervention. Of the 40 women evaluated, 16 had echogenic material in the uterine cavity (mean size 12.7±6.9 cm2). The presence of echogenic material was not associated with the amount or duration of bleeding.Conclusions: Frequent postpartum ultrasonographic findings include a thickened endometrial stripe and echogenic material in the uterine cavity. The echogenic material commonly seen in the endometrial cavity of asymptomatic patients was not associated with the development of bleeding complications.