Umbilical artery velocity waveforms in early pregnancy: A transvaginal color Doppler study

✍ Scribed by Dr. Domenico Arduini; Giuseppe Rizzo

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 389 KB
• Volume: 19
• Category: Article
• ISSN: 0091-2751
• DOI: 10.1002/jcu.1870190603

✦ Synopsis

In a cross-sectional study, umbilical artery velocity waveforms were re- corded in 214 low-risk pregnancies a t 7 weeks to 16 weeks, menstrual age, by means of transvaginal color and pulsed Doppler ultrasonography. In all the cases studied, end diastolic velocities were absent until the 10th week. From this age onward end diastolic velocities were present in a percentage of pregnancies, progressively increasing with gestation and reaching 100% a t 15 weeks. Similarly, the percentage of cardiac cycles in which end diastolic velocities were absent progressively decreased with advancing menstrual age. The normal range for the pulsatility index was constructed and a quadratic function was found to optimally fit its fall during gestation. No differences in pulsatility index values were found at these menstrual ages in 12 pregnancies that later developed intrauterine growth retardation andlor pregnancy-induced hypertension, suggesting that placental alterations causing abnormalities in umbilical velocity waveforms occur later in gestation. Indexing Words: Umbilical circulation * Early pregnancy * Transvaginal ultrasonography -Doppler ultrasonography There is an increasing interest in the application to obstetric practice of Doppler ultrasound examination of umbilical artery (UA) velocity waveforms.' Several studies have shown a progressive increase in diastolic velocities of UA with advancing menstrual age, implying a gradual reduction in placental vascular resistance.233 However, there is still a scarcity of reports on the modifications of UA velocity waveforms in early g e ~t a t i o n ~, ~ and no reference limits for the first trimester of pregnancy have been established.

In this investigation we report our experience on 214 low-risk pregnancies at 7 weeks to 16 weeks, menstrual age (MA), in which velocity waveforms were recorded from the UA by means of transvaginal color Doppler ultrasonography.