Longitudinal quantification of uterine artery blood volume flow changes during gestation in pregnancies complicated by intrauterine growth restriction.

Objective: To quantify and compare longitudinal uterine artery volume flow changes in appropriate for gestational age (AGA) pregnancies and those complicated by intrauterine growth restriction (IUGR).

Design: Serial longitudinal study.

Setting: Large UK Teaching Hospital Obstetrics and Gynaecology Department and Institute of Anatomy, RWTH Aachen, Germany.

Population: Pregnant women with accurately dated singleton pregnancies.

Methods: Quantified uterine volume flow was prospectively measured by colour power angiography in (a) 32 women with abnormal uterine artery Doppler velocimetry at 20 and 24 weeks of gestation and with risk factors for IUGR (IUGR group) and (b) 25 women with normal uterine artery Doppler velocimetry and no risk factors for IUGR (AGA group) between 20 and 38 weeks of gestation. Values obtained from each gestation were compared using unpaired t test.

Main Outcome Measures: Gestational age at delivery, birthweight and total quantified volume flow (mL/min) per gestation in IUGR and AGA pregnancies.

Results: Twenty of the 32 women recruited into the IUGR group and 18 of the 25 controls fulfilled the criteria for inclusion in the analyses. The mean birthweight [SD] and gestational age [SD] at delivery in the IUGR and AGA groups were 2634 [277] versus 3429 [349] g and 39.5 [1.2] and 41.1 [2.3] weeks, respectively. The diameter of the proximal uterine artery just after it crosses the external iliac artery was smaller in the IUGR group from as early as 20 weeks of gestation but this difference only became statistically significant from 24 weeks of gestation and widened as pregnancy advanced. The quantified volume flow in the IUGR group was significantly less than that in the AGA throughout the study period (287 [117] versus 328 [159] mL/min at 20 weeks (P < 0.05), 334 [169] versus 538 [181] mL/min at 24 weeks [P < 0.004] and 534 [332] versus 830 [284] mL/min at 38 weeks of gestation [P < 0.002]). Volume flow in the IUGR group was 12.5% and 36.7% less than that in the AGA group at 20 and 28 weeks of gestation, respectively.

Conclusions: Proximal uterine artery diameter and quantified volume flow change with gestation and show significant differences between AGA pregnancies and those complicated by IUGR. These changes occur early and become more marked as pregnancy advances. Early use of these measurements may identify pregnancies at risk of complications.