Diagnostic Accuracy of B-HCG and Nitrazine Paper Test in Vaginal Washings Taking Amniotic Fluid Pooling as Gold Standard of Diagnosing Premature Rupture of Membranes

Abstract

Background: Premature Rupture of Membranes (PROM) is common in obstetrics and management of such patients depends on whether the rupture has occurred or not. With membranes ruptured the fetus is deprived of protection provided within the amniotic cavity. Beta-Human chorionic gonadotrophin (β-HCG) is a hormone and is present in high concentration in amniotic fluid as well as in the blood and urine of the mother and is studied as possible predictor of preterm labour and as marker of PROM.
 Objective: To compare the diagnostic accuracy of B-hCG & nitrazine paper test in vaginal washings taking amniotic fluid pooling as gold standard for diagnosing premature rupture of membranes.
 Material & Methods: It was a comparative cross-sectional study conducted at Unit Department, of Obstetrics & Gynecology, Lahore General Hospital, Lahore. After that vaginal washings were taken for β-hCG testing. A pregnancy test kit (Accu Check) was used for detection of β-hCG in vaginal fluid washings. According to amount of µ-hCG in the washings the result has been positive as early as 40 Seconds but for labeling the result negative 5 minutes complete reaction time has been observed. On netrizine kit, the positive test is indicated by distinct colour band on both; control and test side.
 Results: Mean age of women was 27.17+4.55 years. Mean age of gestation was 36.16 + 3.30 weeks. Sensitivity & specificity of Nitrazine Paper Test were 92.17% & 66.67%. However the PPV & NPV for Nitrazine Paper Test was 98.15% & 30.77% respectively. Sensitivity & specificity of β-hCG Test was 94.35% & 75%. However the PPV & NPV for β-hCG test was 98.64% & 40.91% respectively.
 Conclusion: Results of this stud y showed that B-subunit of hCG measured by over-the-counter available pregnancy test kit is a dependable quick and easy test for detection of premature rupture of membranes. This test can be performed on the bed side of the patient without Lab involvement. This test can be promoted as an additional help for the diagnosis of doubtful and ambiguous cases of premature rupture of membranes.