Comparison of ELISA and Three Rapid HCG Dipsticks in Diagnosis of Premature Rupture of Membranes

Background: The importance of accurate diagnosis of premature rupture of membranes (PROM) is quite apparent while trying to diminish false negative or positive results as much as possible. This study compares Enzyme- Linked Immunosorbent Assay (ELISA) and three rapid human chorionic gonadothropin (HCG) dipsticks in diagnosis of premature rupture of membranes. Methods: During 2008-2009, 181 pregnant women with single pregnancy from 14 to 41 weeks of gestation who referred to Ayatollah Taleghani Hospital in Tehran, Iran were divided into two groups, 91 patients with PROM and 90 controls with matched gestational weeks. All patients underwent speculum examination for cervicovaginal washing fluid, HCG three rapid tests and ELISA. Results: The HCG concentration of vaginal fluid was significantly different between the two groups. Using receiver operating characteristic (ROC) curve and determining the threshold as 19 mIU/mL for HCG by ELISA method, the sensitivity was 94.5%; specificity, 91%; positive predictive value, 91.5%; negative predicted value, 94.2% and accuracy was 92.2%. In rapid diagnostic test, the most sensitivity was for ACON and the most specificity for DIMA. Comparing the four methods, DIMA strip showed the highest accuracy and the highest value in early diagnosis of ROM. Conclusion: The reliability of three rapid diagnostic tests in diagnosis of ROM in cervicovaginal discharge was acceptable.