Evaluation of a rapid strip test for insulin-like growth factor binding protein-1 in the diagnosis of ruptured fetal membranes

Abstract

We evaluated the clinical usefulness of a new bedside test (PROM TEST) for insulin-like growth factor binding protein-1 (IGFBP-1) in the detection of ruptured fetal membranes (ROM). Cervicovaginal secretion was sampled between 15 and 37 weeks of gestation from asymptomatic women with apparently intact membranes and from women with clinically confirmed ROM, as well as from symptomatic women with suspected ROM based on history. IGFBP-1 in samples was detected with a dipstick based on immunochromatography. The test result was positive in 100% of cases with unequivocal ROM and in 5.3% of cases with apparently intact membranes. Furthermore, the PROM TEST was positive in 64 of 181 patients evaluated for suspected ROM based on history, but in whom the diagnosis could not be clinically confirmed at the initial evaluation. Fifty of the 64 women (78.1%) were delivered prematurely (< 37 weeks). Five of the 117 PROM-negative patients had elective cesarean section for reasons unrelated to ROM before 37 weeks and 10 of the remaining 112 patients (8.9%) had preterm delivery. Women with equivocal ROM and a positive test result had a 6.9-fold increased relative risk (95% confidence interval 4.2–11.4) of preterm delivery compared with women who had a negative result at the time of evaluation. Multiple logistic regression including PROM TEST result, contractions, vaginal bleeding and cervical changes indicated that a positive PROM TEST result was an independent predictor of preterm delivery ( P = 0.0001). In summary, a positive PROM TEST result identifies ROM with high sensitivity and a negative result effectively excludes those with intact membranes. In patients with suspected but clinically unconfirmed ROM, the positive test result is associated with increased risk of preterm delivery, suggesting that microruptures of fetal membranes can also be detected by the PROM TEST.