Screening utility of umbilical artery Doppler indices in patients with preeclampsia

Background: Doppler indices of umbilical artery are used as indicator of fetal well being.
Objective: To compare Doppler parameters of umbilical artery including pulsatility index (PI) and resistance index (RI) in patients with preeclampsia with those of normal pregnancies and to evaluate the diagnostic characteristics of these parameters in preeclampsia.
Materials and Methods: In a case control study, umbilical artery pulsatility and resistance indices were calculated at a free loop of umbilical cord in 25 preeclamptic patients and 75 uneventful pregnancies. Measurements were compared and diagnostic characteristics of the indices were determined.
Results: Mean of pulsatility and resistance index were significantly higher in preeclampsia patients than the control group. Besides, patients with severe preeclampsia showed significantly higher values of PI and RI in comparison to those with mild preeclampsia. For PI, the cut-off of ≥0.98 yielded the highest sensitivity and specificity. Also, RI of 0.64 acquired a sensitivity of 100% and specificity of 44%.
Conclusion: Umbilical artery pulsatility index and resistance index increase in preeclampsia and these changes tend to be greater in severe preeclampsia. Umbilical artery PI and RI seem to be more appropriate in excluding preeclampsia rather than confirming it, and we propose the cut-off values of 0.98 for PI and/or 0.64 for RI, to rule-out the disease.