D-Dimer levels during pregnancy and postpartum: non-applicability of regularly used cut-offs for diagnosis of suspected pulmonary embolism.

purposeTo assess D-dimer levels during pregnancy and postpartum period and evaluate the appropriateness of commonly used cut-offs for ruling out pulmonary embolism (PE) in this population.

methodsSecondary analysis of the prospective PPH 1300 study conducted at the University Hospital Zurich, including 1309 women between 25 + 0 and 42 + 3 weeks of gestation without acute thromboembolic events. D-Dimer levels were measured at admission for delivery and 24-48 h postpartum, stratified into four gestational age groups.

resultsMedian D-dimer values were 1.56 mg/L (IQR 1.20-2.12) antepartum and 1.78 mg/L (IQR 1.25-2.84) postpartum. Antepartum, 99.3% of women had levels ≥ 0.5 mg/L and 88.8% ≥ 1.0 mg/L; postpartum, 98.8% and 88.1% exceeded these cut-offs, respectively. Antepartum values showed an increasing trend with gestational age, whereas postpartum values remained uniformly elevated. No clinically relevant thromboembolic events occurred during the index hospitalization.

conclusionsNearly all pregnant and postpartum women exceed conventional D-dimer thresholds also in the absence of thromboembolism. Standard cut-offs of 0.5 and 1.0 mg/L are therefore unsuitable in obstetric practice, limiting the applicability of general diagnostic algorithms, such as YEARS and Geneva, unless specifically adapted. Trimester- and postpartum-adjusted thresholds or alternative biomarkers are needed to reduce unnecessary imaging and improve clinical management.