Diagnostic accuracy of insulin-like growth factor binding protein-1 for amniotic fluid embolism

Objective: To test whether serum insulin-like growth factor binding protein-1 could be used as a biomarker of amniotic fluid passage into the maternal circulation. Design: Case-control study. Setting: Thirteen centers in France. Patients: This case-control study included a group with amniotic fluid embolism (the amniotic fluid embolism group) and a group with symptoms unrelated to amniotic fluid embolism (the non-amniotic fluid embolism group). Serum insulin-like growth factor binding protein-1 level was measured within 6 hrs from onset of symptoms. We also determined serum insulin-like growth factor binding protein-1 in four additional groups of patients with 1) postpartum hemorrhage, 2) uncomplicated labor, 3) normal pregnancy, and 4) non-pregnant patients with acute pulmonary embolism. Interventions: None. Measurements: Serum insulin-like growth factor binding protein-1 levels were determined using an immuno-enzymatic assay. Main results: The amniotic fluid embolism group included 25 patients, the non-amniotic fluid embolism group had 20 patients, the postpartum hemorrhage group had 24 patients, and the uncomplicated labor group had 50 patients. The serum levels of insulin-like growth factor binding protein-1 were higher in the amniotic fluid embolism group (234 134-635 mu mol/L) compared with the non-amniotic fluid embolism, postpartum hemorrhage, and uncomplicated labor groups, which had serum levels of 56 36-91 mu mol/L, 65 39-91 mu mol/L and 49 30-78 mu mol/L, respectively (p < .001). Serum insulin-like growth factor binding protein-1 level was not different in women during normal pregnancy (57 37-85 mu g/L) compared to the uncomplicated labor group. Patients with acute pulmonary embolism had the lowest insulin-like growth factor binding protein-1 level (52-14 mu g/L). The area under the receiver-operating-characteristic curve for serum insulin-like growth factor binding protein-1 was 0.98 0.97-1.00 for the amniotic fluid embolism diagnostic. Insulin-like growth factor binding protein-1 rose from 56 43-90 mu g/L before symptoms to 458 161-1514 mu g/L after the onset of symptoms in ten patients with available measurements of baseline serum insulin-like growth factor binding protein-1. Conclusion: Increased serum levels of insulin-like growth factor binding protein-1 appear to be a valuable biomarker of amniotic fluid passage into the maternal circulation and may be used to diagnose amniotic fluid embolism. (Crit Care Med 2012; 40:2059-2063)