The Efficacy of Vaginal Fluid B-hGC Levels for Detecting Premature Rupture of Membranes

Yoon, Sung Do; Kang, Suk Sun

Abstract

Premature rupture of membranes(PROM) means the rupture of amniotic membranes at any time prior to labor during the gestational period. The dilemma of correctly diagnosing rupture of the fetal membranes is well known as the consequences of management based on an incorrect diagnosis. This study was undertaken to determine if the measurement of B-hCG levels in the vaginal fluid is useful for the diagnosis of premature rupture of membranes. HCG is synthesized and secreted by the placental syncytiotrophoblast and it is normally found in amniotic fluid, maternal urine and blood. We used B-hCG for diagnosis of PROM to exclude the cross reaction with other hormones. After irrigating the posterior vaginal fornix with 3 ml of sterile saline and obtaining vaginal washings, we measured B-hCG levels. The groups were classified normal group(group I), confirmed PROM group(group II ), and suspicious PROM group(groupIII) during the third trimester. The median and 95% confidence intervals(CIS) of vaginal fluid B-hCG in each group(normal, confirmed PROM, suspicious PROM group) were 30.99mIU/ml(range: 0.32-209.89mIU/ml), 188.61mIU/ml(range: 9.65-2095.00mIU/ml), 69.63mIU/ml(range 4.76-349.56mIU/ml). There was significant difference between normal and confirmed PROM group(p<0.05), sensitivity was 95.00%, specificity 80.00%, positive predictive value 82.60%, negative predictive value 94.12%, and accuracy 87.50%, using threshold value of 60mIU/ml. There was significant difference between normal and suspicious PROM group(p<0.05) but the result of the B-hCG was not used in the obstetric decision. In terms of these results, the B-hCG level in vaginal fluid is a useful marker of PROM during the third trimester. A new technic is proposed to confirm the diagnosis of rupture of the membranes based on the introduction of B-hCG in vaginal fluid.