Assessment of Doppler velocimetry versus nonstress test in antepartum surveillance of high risk pregnancy
Keywords:Doppler velocimetry, High risk pregnancy, Nonstress test, Perinatal outcome
Background: High risk pregnancies increase the maternal and fetal morbidity and mortality; and there is a need for appropriate investigation which can diagnose it early and predicts the morbidity and mortality. The objectives of this study were to compare the efficacy of Doppler velocimetry studies and NST in predicting fetal compromise in utero and compare their ability in predicting the perinatal outcome in cases of high risk pregnancies.
Methods: It was a prospective cross-sectional hospital based study conducted at Central Referral Hospital (CRH) which is a teaching hospital of Sikkim Manipal Institute of Medical Sciences (SMIMS). The study was conducted over a period of eighteen months between November 2012 and April 2014. One hundred consecutive cases of high risk pregnancies were enrolled into the study and investigated with NST (non-stress test) and Doppler velocimetry and results were correlated with perinatal outcome. In all cases, accurate gestational age was established from detailed menstrual history and ultrasonographic evidence of gestational age. Detailed examination, history and investigation were undertaken in each patient. Inclusion criteria were patients with singleton pregnancy beyond 34 weeks having one or more high risk factors. In these patients antenatal surveillance was done by Doppler and NST and results of these tests were correlated with perinatal outcome. Based on the Doppler velocimetry and NST results, the study population was divided in to four groups. Pregnant women below 34 weeks, multiple pregnancy and women with no risk factors were excluded from the study.
Results: Maximum (63%) patients belonged to pregnancy induced hypertension (PIH) group, followed by oligohydramnios (11%), and gestational diabetes mellitus (GDM). The study showed that patients with both NST and Doppler waveform abnormal (group D) had the highest percentage of neonatal complication, NICU admissions and perinatal deaths. Even those patients with NST normal but Doppler velocimetry abnormal (group B) had comparatively higher neonatal complications. However, in group with NST abnormal and Doppler velocimetry normal (group C) had no fetal compromise. It was observed that normal NST and normal Doppler velocimetry were not statistically different in predicting fetal compromise and prediction value was low. But abnormal Doppler had statistically significant (p value = 0.021) predictive value in detecting fetal compromise. In cases with abnormal Doppler and fetal compromise, NST was still normal showing that abnormal Doppler waveform was better in predicting the bad perinatal outcome. Three out of 100 cases had absent end diastolic flow (AEDF) and all 3 were associated with perinatal morbidity with 2 perinatal deaths. Cerebroplacental ratio was < 1.08 in seven cases and all seven had neonatal complications including 3 neonatal deaths which also had AEDF. Thus, cerebroplacental ratio was better in detecting fetal compromise as compared to NST.
Conclusions: Doppler velocimetry was better in predicting fetal compromise in comparison to NST in high risk pregnancies. Normal NST and normal Doppler velocimetry were not significantly different in prediction of fetal outcome. Abnormal Doppler value was better in predicting fetal compromise in comparison to abnormal NST.
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