The Role of Doppler Velocimetry in the Management of High Risk Pregnancies

Abstract

Objective To determine whether knowledge of the result of Doppler velocimetry of the umbilical artery is beneficial to the management of a high risk pregnancy. Design Randomised controlled trial. The trial was of the management type, designed to assess benefit accruing from additional information supplied by Doppler velocimetry. Setting Tygerberg Hospital, Cape Town, South Africa. The hospital serves a population from the lower socio-economic groups. Subject Women with pregnancies 28 or more weeks gestation with hypertensive diseases and/or suspected small for gestational age fetuses were referred for Doppler velocimetry. From this population, three subsets were formed: 1. those with fetuses with absent end-diastolic velocities (20 fetuses); 2. those with hypertension but with fetuses with end-diastolic velocities (89 fetuses); and 3. those with fetuses suspected of being small for gestational age but with end-diastolic velocities (104 fetuses). Interventions Doppler velocimetry on all subjects. The study group consisted of 10 cases with absent end-diastolic velocities, 47 cases with hypertensive diseases with end-diastolic velocities and 51 cases with suspected small for gestational age fetuses but with end-diastolic velocities in which the result was revealed to the clinician. The control group consisted of 10, 42 and 53 cases, respectively, in which the Doppler results were not revealed. All other routine investigations (sonar and antenatal fetal heart rate monitoring) were available to the clinicians. Standard management protocols were followed in all groups. Main outcome measures Perinatal mortality and morbidity, antenatal hospitalisation, maternal intervention, admission to the neonatal intensive care unit and hospitalisation until discharge from the neonatal wards. Results In the study and control groups the gestational age at entry to the study, maternal age, parity and various complications were not significantly different. In the subset with absent end-diastolic velocities, there was one neonatal death in the study group, but in the control group there were six deaths, five intrauterine and one perinatally related infant death (P= 0.029). Because of this significant finding, the study was stopped. There were no differences in outcome in the subset where there was hypertensive disease with end-diastolic velocities between the study and control groups. In the subset in which small for gestational age fetuses were suspected, but in which end-diastolic velocities were present, the women in the study group had significantly fewer days in hospital before delivery (P < 0.001) and tended to have fewer maternal interventions (study group = 27%, control group = 43%; P= 0.07; odds ratio (OR) 0.49, 95% confidence limits (CL) 0.2 and 1.25) and caesarean sections (study group =13%, control group = 27%; P= 0.08; OR 0.43, 95% CL 0.14 and 1.32). The infants of the study group in this subset also spent significantly less time in the neonatal wards (P= 0.029). Conclusions Within the confines of this study, knowledge of the Doppler velocimetry result was beneficial in the subsets with absent end-diastolic velocities and in which intrauterine growth retardation was suspected. In the subset in which women had hypertension but whose fetuses had end-diastolic velocities, there was no beneficial or adverse effect.