Vaginal fluid human chorionic gonadotropin for detection of rupture of membranes

To evaluate the accuracy of qualitative and quantitative human chorionic gonadotropin (hCG) assays to detect ruptured amniotic membranes (ROM) in term patients.

We conducted a prospective cohort study enrolling 100 term pregnancies with intact membranes. Samples were collected before and immediately following ROM, and at 2 and 4 hours post-ROM. Quantitative and qualitative hCG assays were performed on all samples. Outcome measures included the detection and measured amount of hCG before and after ROM. Sensitivity, specificity and positive predictive values for the qualitative assays were determined.

A total of 98% pre-ROM and 100% post-ROM qualitative assays tested positive with mean quantitative hCG levels of 181.30 mIU/mL and 208.24 mIU/mL, respectively. The qualitative post-ROM sensitivity was 100%; however, the pre-ROM specificity was only 2%. The positive predictive value for detecting ROM was 50%.

Qualitative and quantitative hCG assays are not useful for determining ROM in term pregnancies.