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

PURPOSE: To 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. METHODS: Secondary 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. RESULTS: Median 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. CONCLUSIONS: Nearly 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.