Uterine artery Doppler velocimetry in relation to trophoblast migration into the myometrium of the placental bed.

OBJECTIVE

To test the hypothesis that an abnormally high resistance in the uterine artery indicates impaired trophoblast migration into the myometrium of the placental bed.

METHODS

Doppler velocimetry in the uterine artery was carried out in 43 pregnant women within 7 days before cesarean delivery and placental bed biopsy. A pathologist evaluated the placental bed biopsies histologically. Trophoblast migration was absent in 28 cases (impaired migration group) and present in 15 (migration group). Clinical characteristics were compared between these two groups.

RESULTS

There was no significant difference in the mean gestational ages at delivery in the two groups, but those with impaired migration included a higher incidence of small for gestational age infants (46.4 versus 6.7%, P < .01) and a lower mean (+/- standard deviation) birth weight (1622 +/- 528 versus 2287 +/- 748 g, P < .01). The systolic-diastolic ratio (S/D) in the uterine artery was higher in the impaired migration group (2.45 +/- 0.81 versus 1.92 +/- 0.34, P < .05). The absence of migration could be deduced from the S/D of the uterine artery, with a predictive value of 92.3% when we set the cutoff value of the ratio at 2.5.

CONCLUSION

The results suggest that abnormal uterine artery flow velocity waveforms may indicate impaired trophoblast migration into the myometrium of the placental bed.