Umbilical artery doppler abnormalities and associated factors in women with pre-eclampsia at Mulago Hospital- a cross sectional study

Abstract

Background: Umbilical artery (UA) Doppler velocimetry detects foetuses at risk of asphyxia from IUGR before changes in the CTG and biophysical score are evident. This has made it a primary fetal surveillance tool in pre-eclampsia in developed countries with resultant reduction in perinatal mortality by 29%. Iatrogenic preterm deliveries related to pre-eclampsia are a key contributor to neonatal intensive care admissions at Mulago hospital due in part to limited use of UA Doppler velocimetry to optimize delivery because of high patient load.

Objective: The objective was to determine the prevalence and factors associated with UA Doppler abnormalities in women with preeclampsia from 28 weeks of pregnancy so as to identify a subpopulation who would require routine UA Doppler velocimetry to improve perinatal outcomes in a resource limited context.

Study design: This was a cross-sectional analytical study. Maternal age, Gestational age, Parity, and Blood pressure were recorded. Degree of proteinuria, Platelet count, serum creatinine and liver transaminases were analysed and UA Doppler sonography was performed to determine the RI, S/D ratio, AEDV and RF patterns. These data were entered into EPIDATA 3.1 and exported to STATA version 12 for analysis. Bivariate and Multivariate analysis were deployed to identify factors associated with Doppler abnormalities.

Study Setting: The study was conducted on the labour and maternal-fetal medicine wards of Mulago National Referral hospital, Kampala Uganda between June and September 2014.

Subjects: A total of 155 women with pre-eclampsia between 28 and 42 weeks of pregnancy were consented/assented and recruited for the study. Critically ill  patients and those in active phase of labour or premature rupture of membranes were excluded.

Results: The overall prevalence of UA Doppler abnormalities was 31.6%. High RI, high S/D ratio, AEDV and RF were found in 25.8%, 31.6%, 7.7% and 4.5% of the population respectively. Key factors associated with UA Doppler abnormalities were gestational age below 35 weeks (AOR=8.1, 95% CI: 2.91- 22.76, P<0.001), severe pre-eclampsia with heavy proteinuria (AOR=7.3, 95% CI: 2.82-18.87, P<0.001), and multiparity (AOR=5.3, 95% CI: 1.52-18.53, P<0.001). Severe pre-eclampsia comprised 61% (n=95) of the study population. Maternal age and pre-eclampsia with light proteinuria had no association with UA Doppler abnormalities.

Conclusion: UA Doppler abnormalities are very common in pre-eclampsia. Gestational age below 35 weeks and heavy proteinuria are the key associated factors of these abnormalities.