Contribution of blood detection of insulin-like growth factor binding protein -1 for the diagnosis of amniotic-fluid embolism: a retrospective multicentre cohort study.

OBJECTIVE To assess the contribution of maternal blood detection of IGFBP-1 for the diagnosis of amniotic-fluid embolism in clinical daily practice. DESIGN A retrospective multicentre cohort study. SETTING Three tertiary care obstetric units in France. SAMPLE Data of 86 women for whom amniotic-fluid embolism had been suspected and maternal serum detection of IGFBP-1 had been performed between 2011 and 2019 were analysed. METHODS The criteria defined by the United Kingdom Obstetric Surveillance System (UKOSS) were used for the retrospective diagnosis of amniotic-fluid embolism. The more structured definition proposed by the Society for Maternal-Fetal Medicine and the Amniotic Fluid Embolism Foundation (SMFM) was also used as secondary endpoint. MAIN OUTCOME MEASURES Agreements between biological and clinical assessments were tested. The performance of blood detection of IGFBP-1 for the diagnosis of amniotic-fluid embolism according to the UKOSS criteria, and to the SMFM definition, was also assessed. RESULTS There was only slight agreement between clinical and laboratory diagnosis of amniotic-fluid embolism (Cohen's Kappa coefficient: 0.04). Blood detection of IGFBP-1 had a sensitivity of 16%, a specificity of 88%, a positive and a negative likelihood ratio of 1.3 and 0.95, respectively, and a positive and a negative predictive value of 58% and 50%, respectively, for the diagnosis of amniotic-fluid embolism based on the UKOSS criteria. The use of the more structured SMFM definition of amniotic-fluid embolism did not substantially change the results. CONCLUSION These results question the usefulness of blood detection of IGFBP-1 for the early diagnosis of amniotic-fluid embolism in daily clinical practice.