Intervillous and spiral artery flows in normal pregnancies between 5 and 10 weeks of amenorrhea using color Doppler ultrasonography.

OBJECTIVE

The aim of our study was to investigate early placental circulation development and spiral and uterine artery flows in normal 1st-trimester pregnancies.

METHODS

A prospective study of intervillous and spiral artery flows in 49 normal pregnancies (5-10 weeks of amenorrhea) was performed. Transvaginal color and pulsed-wave Doppler techniques (6-MHz probe) were used as routine ultrasound scanning modalities before pregnancy termination for psychosocial reasons.

RESULTS

In all pregnancies, between 5 and 10 weeks, continuous nonpulsatile intervillous flow (mean V(max) 3.55 cm/s) and spiral artery flow (mean peak systolic velocity 16.2 cm/s, mean diastolic index D/S 0.49 +/- 0.089) were detected. In the 47 women in whom the uterine artery flow was measured, the mean peak systolic velocity was 67.5 cm/s, the mean diastolic index was 0.12, and bilateral notching was observed.

CONCLUSIONS

In all cases, between 5 and 10 weeks, slow and continuous nonpulsatile intrachorionic flow could be detected, whereas pulsatile flow was detected in spiral arteries. The true nature of this early intervillous circulation remains to be determined.