Vaginal fluid urea and creatinine, an untapped diagnostic tool for premature rupture of membranes

Abstract

Purpose: The diagnosis of premature rupture of membranes (PROM) can be difficult in equivocal cases. This study was designed to test the validity of vaginal fluid urea and creatinine in the diagnosis of PROM against the gold standard, the Amnisure ROM test™ METHODS: The study was a prospective observational study. All consenting eligible pregnant women between gestational ages of 28 weeks to 41 weeks + 6 days were recruited from the obstetrics emergency and antenatal clinic of the Federal medical centre, Keffi. Patients with history of drainage of liquor were recruited as the case group, and controls who match for age, parity and gestational age were recruited from the antenatal clinic to constitute the control group. Vaginal fluid aspirated was assessed in the laboratory for urea and creatinine levels and an Amnisure ROM test™ done. The sensitivity, specificity, negative and positive predictive values of vaginal fluid urea and creatinine were assessed in the diagnosis of PROM.

Results: Vaginal fluid urea and creatinine had sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), respectively, of 94%, 82%, 93.18% and 83.93%, and 98%, 90%, 97.82% and 90.74%. The cutoff values for vaginal fluid urea and creatinine were 1.25 mg/dl and 0.23 mg/dl, respectively.

Conclusions: This study has found that vaginal fluid urea and creatinine are very effective tests in diagnosis of PROM. It is a cheaper and more readily available alternative to the Amnisure test. It is especially useful in our environment, especially in cases of equivocal PROM, as a cost-effective means to confirm the diagnosis.

Trial registration number (nigeria clinical trial registry): 72961653, retrospectively registered on the 2020-07-09.

Keywords: Amnisure; Creatinine; Urea; Vaginal fluid.