Spatial Configuration of the Uterine Artery Cervical Segment in 3-Dimensional Reconstruction at 11 to 14 Weeks' Gestation.

Uterine artery blood flow measurement is an important component of preeclampsia screening in the first trimester. Transabdominal measurement of the uterine artery pulsatility index has been reported to have relatively low interobserver reproducibility, mainly because the uterine artery is not sampled in the same place every time. We assessed the uterine artery pathway using 3-dimensional power Doppler reconstruction. We found that the artery always forms a loop at the level of the uterine cervix, with anterior descending and posterior ascending segments. The loop spatial position and the appearance of its segments vary according to the parity. In nullipara, the loop is most times regular, with some variations in orientation. It has an anteroposterior position above or at the level of the internal os, and it represents the most inferior point of the uterine artery at this level. In multipara, the loop is almost always rotated; its segments are tortuous and more elongated. The loop is often not the most inferior point of the uterine artery, and its anterior afferent segment sometimes descends below to the level of the loop. Three-dimensional reconstruction can clearly show the appearance of the uterine artery at the level of the cervix. Understanding the spatial arrangement of the uterine artery could enhance the performance of pulsatility index measurement.