Uterine artery Doppler patterns in abdominal pregnancy.

Changes in the uterine artery blood flow waveform during pregnancy have been the subject of several studies and are frequently attributed to trophoblastic invasion of the myometrium. We report on a case of a third-trimester abdominal pregnancy in which we performed Doppler velocimetry of the uterine arteries and observed low-resistance flow and absence of notching bilaterally. During the 29th week of gestation, there was an increase in umbilical artery resistance and a decrease in the middle cerebral artery resistance, so we chose to deliver the baby at that stage. The patient was discharged from hospital 7 days following delivery and the child was discharged having gained the necessary weight. Our findings suggest that modification of the uterine artery waveform may occur independently of trophoblast invasion of the spiral arteries. Other theories that may explain the changes in the uterine artery waveform during pregnancy are discussed.