Serum C3 and uterine artery Doppler indices at 14-20 weeks gestation for preeclampsia screening in low-risk primigravidas: A prospective observational study

•Serum C3 and Uterine artery Doppler for early prediction of PE.•SerumC3 at 14-20 weeks has comparable results to Uterine artery Doppler for early prediction of PE.•Serum C3 has the advantage of being operator independent.

ProblemPreeclampsia affects 2-10% of human pregnancies with poor screening tests. In order to intervene preventively, high risk population should be identified before the 20th week of pregnancy and by a method not subjected to operator efficiency.MethodologyProspective observational study recruiting 825 low risk primigravidas. Serum C3 and uterine artery Doppler indices were measured at 14-20 weeks.ResultsSerum C3 levels at 14-20 weeks of gestation had a sensitivity 83.3%, specificity 100%, PPV 100% and NPV 98.3% when the cut-off value was 53.1 mg/. For the mean RI, the best cut off value found was 0.72 with 100% sensitivity, 99.1% specificity, 92.3% PPV and 100% NPV. For the mean PI the best cut off value was 1.35 with 100% sensitivity, 94.1% specificity, 63.2% PPV and 100% NPV. The combination of serum C3 level and mean uterine artery PI showed 100% sensitivity, 97.4% specificity, 80% PPV and 100% NPV in prediction of PE.ConclusionSerum C3 levels at 14-20 weeks can be used for prediction of PE with comparable results to uterine artery Doppler indices but has the superiority of being operator independent.