Written by Jason Lesnick
Pregnant patients who present with signs and symptoms concerning for pulmonary embolism (PE) can be safely evaluated using Wells criteria or the YEARS algorithm.
Why does this matter?
PE is one of the most common causes of death in pregnancy in developed countries due to the hypercoagulable state of pregnancy, but there is significant overlap between features of normal pregnancy and possible venous thromboembolism. This study aimed to evaluate diagnostic strategies to efficient, safely and efficiently exclude PE while sparing the pregnant patient and fetus from CT imaging.
Wells, which is it – Wells, YEARS, both, or neither?
This systematic review identified 2 studies including 893 pregnant women and excluded 45. The authors then performed an individual patient data meta-analysis comparing Wells with and without adjusted D-dimer thresholds as well as the YEARS algorithm looking for sensitivity, specificity, failure rate (3-month venous thromboembolism (VTE) incidence after excluding PE without chest imaging), and efficiency (the proportion of patients in whom chest imaging was avoided).
The authors included studies if they enrolled ≥ 50 consecutive pregnant patients with clinically suspected acute PE who were prospectively managed according to a predefined diagnostic strategy, starting with the determination of clinical pretest probability (CPTP) and D-dimer testing. The 2 studies were the CT-PE and Artemis studies, which we have previously covered.
Baseline prevalence of acute PE was 5.4% in the merged database (first trimester: 13%, second trimester: 4.0%, and third trimester: 3.5%) Sensitivity was highest for the Wells rule with a fixed D-dimer threshold and the YEARS algorithm, as both yielded a sensitivity of 98% (95% CI, 89 to 100 and 95% CI, 88 to 100, respectively). The Wells rule with D-dimer threshold dependent on CPTP yielded a sensitivity of 90% (95% CI, 78-96).
The failure rate in patients with non-high pretest probability and a normal D-dimer test was 0.96% (1/104; 95% CI, 0.01-5.8) for the Wells rule with fixed D-dimer threshold, 1.4% (5/365; 95% CI, 0.49-3.3) for the Wells rule with D-dimer threshold dependent on CPTP, and 0.37% (1/272; 95% CI, 0.01-2.3) for the YEARS algorithm. Specificity was highest when applying the Wells rule with D-dimer threshold dependent on CPTP (44%; 95% CI, 40-47), followed by the YEARS algorithm (32%; 95% CI, 29-36), and lowest when applying the Wells rule with the fixed D-dimer threshold (12%; 95% CI, 10-15).
The strategy that yielded the highest proportion of patients in whom chest imaging could be avoided was the Wells rule with D-dimer threshold dependent on CPTP, 43% (95%CI 40-46); which was followed by the YEARS algorithm, 32% (95%CI 29-35); and the least efficient was the strategy applying the Wells rule with the fixed D-dimer threshold, 13% (95%CI 11-15).
There doesn’t seem to be much benefit from compression ultrasound of the lower extremities when patients lack symptoms of DVT. The efficiency of CUS (CTPAs avoided because of confirmed proximal DVT) was low (0.79%; 95% CI, 0.16-2.4; number needed to test 127).
This study is consistent with the latest ESC guidelines recommending structured assessment and D-dimer testing to rule out PE in non-high-risk pregnant women. Based on current evidence, it seems reasonable to use one of the above strategies to rule out PE in pregnant women.
Peer reviewed by Bo Stubblefield
Editor’s note: For simplicity, as I compare these strategies side by side, I need to pick one. I plan to use the pregnancy-adapted YEARS criteria, which seems to strike the balance of high sensitivity, low failure rate, and decent efficiency (scans avoided). ~Clay Smith
Noninvasive diagnostic work-up for suspected acute pulmonary embolism during pregnancy: a systematic review and meta-analysis of individual patient data. J Thromb Haemost. 2023 Mar;21(3):606-615. doi: 10.1016/j.jtha.2022.11.025. Epub 2022 Dec 22.