Longitudinal Doppler sonographic measurements of vascular impedance in thecentral and peripheral spiral arteries throughout pregnancy

Purpose. We assessed vascular impedance in the spiral arteries in the centr al and peripheral placental bed throughout uncomplicated pregnancies. Methods. Transabdominal color Doppler sonography was used to measure the pu lsatility index (PI), resistance index (RI), and peak systolic velocity in the central and peripheral spiral arteries in 94 women with uncomplicated s ingleton pregnancies. Sonographic examinations took place approximately eve ry 5 weeks from 10 to 40 weeks' menstrual age. Results. PI, RI, and peak systolic velocity were not different in the centr al versus the peripheral segments of the spiral arteries. The PI and RI val ues of central spiral arteries after 25 weeks' menstrual age. The PI and RI values of peripheral arteries decreased after 20 weeks' menstrual age. Conclusions. Additional subjects are needed to clarify changes in the imped ance of central and peripheral spiral arteries over the course of normal an d complicated pregnancies. (C) 2000 John Wiley & Sons, Inc.