Congo red dot test in the early prediction and diagnosis of pre-eclampsia in a tertiary health care centre in India

•This is one of largest single Institute cohort study (N = 378) in India extensively to determine the feasibility and efficiency of the Congo red dot (CRD) test under Indian tertiary clinical setup.•We used CRD test for early prediction of pre-eclampsia in Indian pregnant women and compared the results with the clinical data to determine the correlation. To demonstrate the use of urine congophilia quantification in the prediction and diagnosis of pre-eclampsia using Congo red dot test. A prospective cohort study in 378 consecutive pregnant women was conducted. All eligible, consenting women of gestational age between 10 and 34 weeks were enrolled in the study. The presence of urinary misfolded proteins was screened by a simple dot test technique on unsupported nitrocellulose membrane using Congo red dye. The urinary congophilia was increased in urine from women with pre eclampsia compared to healthy pregnant controls. The mean CRR value of pre eclamptic pregnant women (35.2 ± 9.4%) was five times higher than that of mean CRR value of normotensive pregnant women (6.9 ± 4.7%). The mean gestational age at which Congo red test showed positive was 26.95 ± 2.90 weeks and the time taken from CRD positive to development of PE was 4.92 ± 2.54 weeks of gestation. In our study, the CRD test was not only effective in predicting pre-eclampsia but was also useful in differentiating between pre-eclampsia and other forms of hypertension, as well as early onset and late onset pre-eclampsia, with positive predictive value of 80.36% and negative predictive value of 92.86%