Maternal ophthalmic artery Doppler velocimetry in pre-eclampsia in Southwestern Nigeria

Abstract

Background: Pre-eclampsia (PE) poses a serious challenge to maternal and fetal health in Africa. It is associated with hemodynamic changes that may affect the internal carotid/ophthalmic artery circulation with consequent neuro-ophthalmic manifestations. Ophthalmic artery Doppler (OAD) ultrasound is an important tool that can be used to detect hemodynamic changes in PE and monitor its severity. In this study, we evaluated hemodynamic changes on OAD ultrasound in the ophthalmic arteries of pre-eclamptic women and compared these with values in healthy pregnant women.

Methods: OAD parameters, such as, peak systolic velocity, peak diastolic velocity, end diastolic velocity, pulsatility index, and peak ratio, were measured on transorbital triplex ultrasound scan with a 7-10 MHz multifrequency linear transducer in 42 consenting pre-eclamptic patients and 41 pregnant controls matched for maternal age, gestational age, and parity at the Department of Radiology, University College Hospital, Ibadan. Univariate, bivariate, and receiver operating characteristic curve data analyses were performed. P<0.05 was considered to be statistically significant.

Results: Mean resistivity index, pulsatility index, and peak systolic velocity were significantly lower in pre-eclamptic patients than in the controls. Mean peak diastolic velocity, end diastolic velocity, and peak ratio were significantly higher in the pre-eclamptic group. The receiver operating characteristic curve showed that the resistivity index (sensitivity 75%, specificity 77.8%) could distinguish mild from severe PE while the peak ratio (sensitivity 90.5%, specificity 81.3%) could accurately detect PE.

Conclusion: OAD ultrasound can be used to monitor patients with PE for early detection of progression to severe forms before cerebral complications develop. OAD screening of patients at high risk for PE can also detect early changes of hemodynamic derangement.

Keywords: Doppler parameters; hemodynamic changes; ophthalmic artery; ultrasound.

Figure 1

Pie chart representation of study recruitment shows approximately equal proportions of pre-eclamptic patients and normotensive subjects.

Figure 2

Bar chart representation of the mean values of clinicodemographic characteristics of the normotensive and pre-eclamptic participants in the study. Note the similarity in the maternal and gestational ages of the pre-eclamptic patients and the normotensive patients. Abbreviations: BP, blood pressure; PE, pre-eclampsia.

Figure 3

Box plots for right RI, PI, PR, and EDV in control subjects at GA of 23±2 weeks (n=50), control subjects at GA of 32±2 weeks (n=41) and pre-eclamptic patients (n=42). (A) Box plots for right RI showing a positively skewed distribution in pre-eclamptics. Note that pre-eclamptic patients have lower RI values. (B) Box plots for the right PI showing a normal distribution in all the groups. Note that pre-eclamptic patients have lower PI values. (C) Box plots for the right PR showing a positively skewed distribution in control subjects. Note that pre-eclamptic patients have higher PR values. (D) Box plots for right EDV. A positively skewed distribution is shown in the control subjects. Abbreviations: GA, gestational age; PR, peak ratio; RI, resistivity index; EDV, end diastolic velocity; PI, pulsatility index; Rt, right.

Figure 4

Box plots of MAP, RI, and PI among the pre-eclamptic subjects (mild pre-eclampsia [n=24], severe pre-eclampsia [n=18]). (A) Box plots for mean arterial pressure in those with mild pre-eclampsia and in those with severe pre-eclampsia. (B) Box plots for right RI among those with mild pre-eclampsia and those with severe pre-eclampsia. (C) Box plots for right PI among those with mild pre-eclampsia and those with severe pre-eclampsia. Abbreviations: PE, pre-eclampsia; RI, resistivity index; PI, pulsatility index; MAP, mean arterial pressure.

Figure 5

ROC curves for OAD parameters to predict pre-eclampsia and its severity. (A) ROC curve for PDV to predict pre-eclampsia (AUC 0.69; 95% CI 0.59–0.79). (B) ROC curve for EDV to predict pre-eclampsia (AUC 0.657; 95% CI 0.55–0.76). (C) ROC curve for PR to predict pre-eclampsia (AUC 0.900; 95% CI 0.84–0.96). (D) ROC curve for RI to predict mild pre-eclampsia (AUC 0.709; 95% CI 0.54–0.88). Abbreviations: AUC, area under the curve; CI, confidence interval; ROC, receiver operating characteristic; PR, peak ratio; RI, resistivity index; PDV, peak diastolic velocity; EDV, end diastolic velocity; OAD, ophthalmic artery Doppler.