Which is more accurate vaginal fluid creatinine or human chorionic gonadotropin in diagnosis of premature rupture of membranes

Background: diagnosis of premature rupture of membranes is of utmost importance in the field of obstetrics to decrease possible complications and prevent unneeded intervention. However, there is no gold standard marker for diagnosis of premature rupture of membranes. Aim of the work: This prospective case control study was done to compare the reliability of vaginal fluid creatinine and quantitative human chorionic gonadotropin for diagnosis of premature rupture of membranes. Patients and Methods: The study included 150 pregnant women between 25-34 weeks of gestation attending Al-Azhar University Hospitals. They were divided into three groups: Group (I) (confirmed PROM) consisted of 50 patients with positive history of vaginal leakage and positive fluid leakage observed using sterile Cusco speculum. Group (II) (Suspected PROM) consisted of 50 patients with positive history of vaginal leakage and negative fluid leakage observed using sterile Cusco speculum. Group (III) consisted of 50 pregnant women without any complaint or complication. All patients underwent full history, general examination, abdominal examination and sterile Cusco speculum examination. The vagina was washed by injection with a syringe filled with 3ml of saline solution, and 3ml the washing fluid was collected from the posterior vaginal fornix. The collected fluid was sent immediately to the laboratory for measuring of vaginal fluid creatinine & quantitative HCG. Results: The study showed that there was no significant statistical difference between confirmed, suspected and control groups as regard maternal age, parity and gestational age. There was significant statistical difference between confirmed, suspected and control groups as regard amniotic fluid index. The number of patients with AFI≤ 9 cm was 32 patients in confirmed group, 17 patients in suspected group and 4 patients in the control group. On the other hand the patients with the AFI >9 cm was 18 patients in confirmed group, 33 patients in suspected group and 46 patients in the control group. Analysis of results using Receiver operator characteristic (ROC) curve showed that the best cutoff point for vaginal fluid creatinine among the studied groups in our study was 0.7 mg/dl with sensitivity, specificity, +ve predictive value, +ve predictive value and accuracy were all 100%. In addition, analysis of results using ROC curve showed that the best cutoff point for vaginal fluid HCG among the studied groups in our study was 47.0 mIU/mL with sensitivity 94%, specificity 86%, +ve predictive value 93.1%, +ve predictive value 87.8% and accuracy 91.3%. Conclusion: both vaginal fluid creatinine and HCG concentrations are good predictors of PROM but measurement of vaginal fluid creatinine is more reliable and less expensive than measurement of vaginal fluid HCG in diagnosing PROM.