Comparison of the diagnostic efficacy of the two rapid bedside immunoassays and combined clinical conventional diagnosis in prelabour rupture of membranes

ObjectiveDiagnosis of prelabour rupture of membranes (PROM) may be challenging. Conventional diagnostic methods such as speculum examination, ferning pattern, and pH detection are not satisfactorily accurate. Two relatively new, commercially available rapid bedside immunoassay strip tests, for placental alpha microglobulin-1 (PAMG-1) and insulin-like growth factor binding protein-1 (ILGFBP-1), are alleged to be more accurate. We compared the diagnostic efficacy of PAMG-1 and ILGFBP-1 immunoassay tests and combined conventional clinical diagnostic methods in PROM.Study design167 pregnant women with signs and/or symptoms of PROM were prospectively evaluated with a combination of conventional clinical tests including speculum examination, nitrazine, ferning pattern, and pooling, in addition to PAMG-1 and ILGFBP-1 immunoassays. Differences in sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of the diagnostic methods were compared.ResultsAlthough the PAMG-1 assay was more accurate, the PAMG-1 immunoassay, ILGFBP-1 immunoassay, and combined conventional clinical diagnosis were, in fact, all highly accurate with no significant difference in sensitivity, specificity, PPV, NPV, or accuracy.ConclusionBoth rapid bedside strip tests may be used in clinical practice with similar efficacy in diagnosing PROM, particularly as a backup when diagnosis is still in doubt following a combination of conventional diagnostic methods.