Usefulness of the insulin-like growth factor binding protein-1 bedside test for ruptured fetal membranes

ObjectiveWe evaluated whether phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) in blood or from other sources interferes with the vaginal IGFBP-1 dipstick test in rupture of fetal membranes (ROM). DesignCross-sectional study. SettingAntenatal Clinic, University Hospital. PopulationA total of 247 pregnant women consulting the emergency obstetric unit with self-reported amniotic fluid leakage. MethodsVaginal samples were tested with the IGFBP-1 dipstick test and the concentrations of different IGFBP-1 isoforms were measured by two immunoenzymometric assays. Main outcome measureIGFBP-1 dipstick test result in the presence or absence of blood and different phosphoisoforms of IGFBP-1. ResultsThe dipstick test was positive in 37.2% of women and negative in 62.8% of women. Vaginal bleeding was present in 19.4%. In women with a positive test and clinical evidence of ROM, both IGFBP-1 and phIGFBP-1 concentrations in vaginal fluid were lower in women with than in women without bleeding (p=0.025 and p=0.031, respectively). No difference was found in concentrations of IGFBP-1 and phIGFBP-1 in women with a positive dipstick test without ROM, with or without vaginal bleeding. In women with a negative test the concentrations of IGFBP-1 and phIGFBP-1 remained below the cut-off for the test, regardless of bleeding. IGFBP-1 concentration did not differ by cervical status, but phIGFBP-1 concentration was higher in women with a ripe cervix (p=0.001). ConclusionsRapid vaginal dipstick test can be used in the detection of ROM irrespective of the presence or absence of blood. Positive tests near term indicate either ROM or leakage of less phIGFBP-1 associated with onset of delivery.