Objectives: To define the ultrasonographic appearance of the uterus and the uterine cavity, including its contents, in normal women making an uncomplicated postpartum recovery.
Methods: Forty women were scanned on days 7, 14, and 21 postpartum. At each scan the uterine and cavity volumes were estimated, and the appearance of the uterine cavity contents was documented. The amount and duration of postpartum vaginal bleeding, and method of infant feeding were also recorded.
Results: The mean duration of postpartum bleeding was 24.5 (range 14-45) days. Fifty-one percent (95% confidence interval 34-68) of the subjects scanned at 7 days postpartum, 21%(8-36) at 14 days, and 6%(0.8-20) at 21 days, had an echogenic mass within the uterine cavity. Statistical analysis revealed no difference, in terms of bleeding duration, between women with a uterine cavity echogenic mass noted at 7, 14, or 21 days postpartum, and those without (unpaired t-test, P = 0.42, 0.39, and 0.06). The presence of an echogenic mass was not associated with heavier bleeding at the time of any of the scans (chi-squared test, P = 0.58, 0.56, and 0.28). Statistical analysis revealed no correlation between the duration or amount of bleeding, and the uterine or cavity volume, at any of the three scans.
Conclusion: In this study, ultrasound evaluation of the uterine cavity revealed an echogenic mass in 51% of women with normal postpartum bleeding at 7 days, 21% at 14 days, and 6% at 21 days postpartum. This questions the significance of echogenic material within the uterine cavity in the postpartum period.