RESUMEN
Vaginal bleeding may be present in up to 30% of patients presenting with signs and symptoms of a rupture of the fetal membranes (ROM). The presence of blood may lead to false positive results with biochemical markers. The data presented in this study came from a multi-centric prospective observational clinical study that, for the first time, systematically evaluated the performance of placental alpha microglobulin-1 (PAMG-1) and insulin-like growth factor binding protein-1 (IGFBP-1) detecting tests in 151 women with vaginal bleedings as well as signs and symptoms indicative of ROM. Our data showed better performance for the PAMG-1 compared with the IGFBP-1 detecting tests in all quality parameters evaluated. In detail, sensitivity (SN) was 97.8% (91.0%), specificity (SP) was 91.5% (75.0%), positive predictive value (PPV) was 94.6% (83.5%) and negative predictive value (NPV) was 96.4% (85.7%) for PAMG-1 tests (and IGFBP-1 tests, respectively). A major difference between both tests was related to the number of non-evaluable test results (e.g., hidden bands due to blood smear on the test strips). While 2% of all results were not evaluable for PAMG-1 tests, this artifact appeared in 11% of the results obtained with IGFBP-1 tests. This difference and also those in Specificity and PPV were statistically significant, demonstrating superiority of PAMG-1 over IGFBP-1 detecting tests. In conclusion, the PAMG-1 detecting test was significantly less susceptible to interference by blood than the IGFBP-1 detecting test.