The value of urea, creatinine, prolactin and β-hCG of vaginal fluid in the diagnosis of premature preterm rupture of membranes in pregnancy

Objective: To evaluate the effectiveness of urea, creatinine, prolactin and beta sub-unit of human chorionic gonadotropin (β-hCG) of vaginal fluid in premature preterm rupture of membranes (PROM) diagnosis.

Materials and Methods: In this observational study, 160 pregnant women with gestational age of 28 to 40 weeks were divided into two equal groups: investigation (documented PROM) and control (intact membrane) groups. An amount of 5 cc of normal saline was poured into the vagina of all participants and the spilled liquid was pulled after a few minutes with a syringe. The liquid was sent to a laboratory for examination. Data were analyzed using T-test.

Results: The volume of urea, creatinine, prolactin and β-hCG was significantly different in the two groups (p < 0.001). Based on receiver operating characteristic curve and cut off point, sensitivity, specificity, positive and negative predictive values of β-hCG for detecting PROM were 87.5%, 86%, 86.4% and 87.3%, respectively. Also, the same factors for urea in detecting PROM were 79.7%, 82.5%, 81.8% and 80.4%, respectively. Creatinine had 74.6% sensitivity, 85% specificity, 83% and 77.2% positive and negative predictive values for detecting PROM. Finally, prolactin had 87.5% sensitivity, 90% specificity, 90% positive and 88% negative predictive values for detecting PROM.

Conclusion: Prolactin and β-hCG have more diagnostic value than urea and creatinine in detecting PROM. They can be used in suspected cases.