Strategies to Reduce Advanced Imaging in Antenatal Pulmonary Embolism Diagnostics

Advanced imaging to diagnose pulmonary embolism (PE) during pregnancy increases costs, ionizing radiation exposure, and the risk of overdiagnosis. D-dimer testing can exclude PE and compression ultrasonography can diagnose deep vein thrombosis (DVT), both reducing advanced imaging needs. How these 2 strategies are used in community PE diagnostics is unknown.

To analyze the use and efficiencies of D-dimer and ultrasonography for the diagnosis of antenatal PE.

This retrospective cohort study was performed in 21 US community hospitals from October 1, 2021, to March 31, 2023. Participants included pregnant patients who underwent D-dimer testing, compression ultrasonography, or advanced imaging for suspected PE.

D-dimer testing or ultrasonography.

The main outcome was avoidance of advanced imaging, measured by the number needed to test (NNT) to avoid 1 advanced imaging study using low to intermediate D-dimer values or a positive ultrasonography finding. Variables associated with D-dimer and ultrasonography were evaluated using quasi-Poisson regression reported as adjusted relative risks (ARRs).

A total of 720 outpatient encounters in 699 patients were included in the analysis (median age, 30.2 [IQR, 24.3-36.1] years). D-dimer testing was obtained in 524 patients (72.8%). Advanced imaging was not pursued in 149 of 155 patients (96.1%) with low (<0.5 mg/L) and 82 of 179 (45.8%) with intermediate (0.5 to <1.0 mg/L) D-dimer values, yielding an NNT to avoid 1 advanced imaging study of 2.3 (95% CI, 2.0-2.6). No 90-day venous thromboembolism or death occurred following rule-outs. D-dimer testing was less commonly used in third (vs first) trimester (ARR, 0.85; 95% CI, 0.75-0.97); with unilateral signs or symptoms of DVT (vs none) (ARR, 0.67; 95% CI, 0.54-0.82), and during labor and delivery unit (vs emergency department) evaluation (ARR, 0.27; 95% CI, 0.20-0.35). Compression ultrasonography was performed in 229 patients (31.8%), with DVT diagnosed in 3 (1.3%). Advanced imaging was not pursued in 2 of these patients, yielding an NNT to avoid 1 advanced imaging study of 115 (95% CI, 32-417). Ultrasonography use and results varied by DVT symptoms. Among 55 patients with DVT symptoms, 46 (83.6%) underwent ultrasonography, with positive findings in 3 (yield of 6.5%). Among 665 patients without symptoms, 183 (27.5%) underwent ultrasonography, with negative findings in all (yield of 0).

In this cohort study, use of D-dimer testing was efficient and safe with opportunities for expansion across settings and patients. These findings suggest that ultrasonography efficiency was low but could be improved with symptom-driven use in antenatal PE diagnostics.