COMPARISON OF VELOCITY WAVE-FORMS OF THE UMBILICAL ARTERY OBTAINED BYPULSED AND COMPUTERIZED CONTINUOUS-WAVE DOPPLER IN 3RD TRIMESTER, UNCOMPLICATED PREGNANCIES

Objective: To assess the difference between pulsed-wave Doppler (PD) a nd computerized continuous-wave Doppler (CW) readings of the umbilical artery of 20 parturients in their third trimester of uncomplicated pr egnancy. Methods: In a prospective double-blind study, the systolic/di astolic ratio in the umbilical artery was measured 20 min apart by two different physicians with two different instruments (PD and CW). The resistance index (RI), as well as the intra- and interobserver variati on were calculated. Results: Interobserver variation was not significa nt for both techniques (P > 0.05). The mean S/D ratio measured by PD ( 2.92 +/- 0.52) was significantly higher than that measured by CW. The mean RI in the PD readings was also significantly higher than that mea sured by CW (0.64 +/- 0.07 vs 0.61 +/- 0.06). The intraobserver variat ion was much smaller for CW readings of the S/D ratio than for the PD readings. Conclusions: The more accurate computerized readings of the CW appear to be the reason for the difference in measurements.