Prospective evaluation of blood flow in the myometrium and uterine arteries in the puerperium.

OBJECTIVE

Heavy bleeding in the late postpartum has, in some cases, been attributed to subinvolution of the placental bed and enhanced myometrial vascularity (EMV) as seen on color Doppler imaging. The aim of this study was to investigate the incidence and spontaneous evolution of areas of enhanced vascularization over the whole thickness of the myometrium in asymptomatic women after uncomplicated term pregnancy.

METHODS

This was a prospective descriptive study involving 93 consecutive women who were examined on day 3 (mean 2.6 +/- 1.5) and at 6 weeks (mean 6.5 +/- 1.3) after delivery following an uncomplicated term pregnancy. EMV was defined as the presence of marked flow over the full thickness of the myometrium reaching the uterine cavity. Doppler flow examination within the area of EMV and of both uterine arteries was performed.

RESULTS

The mean patient age was 29.1 years and average parity was 1.7. The mean gestational age at delivery was 39.1 weeks. Areas of EMV were visualized in 50.5% of patients on day 3 vs. 3.9% at 6 weeks. None of the patients required therapy for bleeding problems. The mean pulsatility index and peak systolic velocity in the area of EMV on day 3 were 0.45 +/- 0.30 and 0.37 +/- 0.20 m/s, respectively. A consistent increase in vascular resistance and decrease in blood flow velocity was observed in both uterine arteries between day 3 and week 6.

CONCLUSIONS

Most areas of EMV reflect intermediate stages in the involution of the placental bed and do not cause abnormal postpartum bleeding. EVM is common in the puerperium, disappears spontaneously in the vast majority of cases, and does not warrant treatment if asymptomatic. Further research is needed to predict the rare cases in which subinvolution of the placental bed leads to heavy bleeding in the late postpartum.