Objective: To evaluate the effectiveness of urea, creatinine, prolactin, and the beta sub-unit of human chorionic gonadotropin (β-hCG) of vaginal fluid in the diagnosis premature preterm rupture of membranes (PROM).
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. Five cubic centimeters of normal saline was poured into the vagina of all participants and the liquid was extracted after a few minutes using a syringe. The liquid was sent to a laboratory for examination. Data were analyzed using a 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, and 83% and 77.2% positive and negative predictive values for detecting PROM. Finally, prolactin had 87.5% sensitivity, 90% specificity, and 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, and can be used in suspected cases.
Keywords: Premature preterm rupture of membranes; Prolactin; creatinine; urea; vaginal fluid; β-hCG.