Significance of detecting insulin-like growth factor binding protein-1 in cervicovaginal secretions: comparison with nitrazine test and amniotic fluid volume assessment

OBJECTIVES: The diagnosis of premature rupture of membranes (PROM) is sometimes challenging, and common diagnostic tests are of limited value in the diagnosis. We aimed to study the accuracy of detecting insulin-like growth factor binding protein-1 (IGFBP-1) in vaginal fluid by a rapid dipstick method in comparison with the nitrazine test and amniotic fluid index (AFI) and we studied the predictivity of these methods on the latency of pregnancy in patients with suspected PROM. MATERIAL AND METHOD: One hundred and fifty-one patients (36 definite PROM, 35 no PROM and 80 suspected PROM) at 20-42 weeks' gestation were included in the study. Patients with preterm labor and PROM, patients at <20 gestational weeks, and those with multiple pregnancies were excluded. IGFBP-1 in the cervicovaginal fluid was measured by a rapid dipstick method (PROM test). AFI was measured by the four-quadrant method and an AFI of <80 mm was considered as oligohydroamnios. RESULTS: The sensitivity, specificity and accuracy of the nitrazine test, the PROM test and AFI were 97, 16 and 56%, 97, 97 and 97% and 94, 91 and 92%, respectively. The nitrazine test results were affected by vaginal discharge but the PROM test results were not affected. Only a positive PROM test was associated with delivery within 7 days [odds ratio (OR) 12; 95% confidence interval (CI) 4.2-35, p < 0.001]. CONCLUSION: The dipstick method of detecting IGFBP-1 in the vaginal fluid is a rapid, reliable and noninvasive method. The PROM test is the most accurate diagnostic test and predictor of latency in patients with suspected PROM.