Diagnosis of PE in Pregnancy: Applying a Simple Algorithm to Reduce the Need for CT Manuela Noriega, DO and Christopher Perry, MD
T
he diagnosis of pulmonary embolism (PE) in pregnancy represents one of the most challenging scenarios faced by emergency medicine physicians. Pregnant patients are not only at higher risk for venous thromboembolism (VTE), but also present a number of unique diagnostic challenges for the clinician. The rate of VTE among pregnant or postpartum patients has been estimated at 1.72 per 1000 deliveries,1 with a relative risk of 4.29%.2 Exacerbating the issue is that fears of radiation exposure and iodinated contrast to the mother and fetus often make the clinician, and the patient, hesitant to proceed with necessary imaging studies.
diagnosis was felt to be PE. A d-dimer level was also measured in parallel with this assessment.
Unfortunately, a scarcity of strong data on the subject has led to a lack of consensus recommendations from international societies on how to proceed in the management of pregnant patients presenting to the ER with signs or symptoms suggestive of PE.3-5
Over the course of the study, 510 consecutive pregnant women with clinically suspected pulmonary embolism were screened, of whom 12 were excluded. Of the 498 remaining patients, 252 (51%) met none of the three YEARS criteria, and 246 (49%) met at least one of the criteria. Of those who met at least one of the criteria, 19 (7.7%) had hemoptysis, 47 (19%) had clinical signs of deep-vein thrombosis, and 218 (89%) were considered to have PE as the most likely diagnosis.
In 2019, the Artemis Study Investigators6 adapted the previously validated YEARS criteria7 to pregnant patients with clinically suspected PE. In this multi- center, international study, pregnant patients over the age of 18 were prospectively screened over a five year period if they were suspected to have a PE, based on having new onset chest pain or dyspnea with or without hemoptysis or tachycardia. Management followed the pregnancy-adapted YEARS criteria (Figure 1). Three criteria were assessed: presence of clinical signs of deep venous thrombosis (DVT), reported hemoptysis, and whether the most likely Figure 1: Pregnancy Adapted YEARS Criteria
If a patient had signs suggestive of DVT, two-point (inguinal and popliteal) compressive ultrasonography of the deep veins of the symptomatic leg was performed. If this confirmed DVT, then the diagnosis of PE was felt to be established and no further diagnostic imaging was performed. Otherwise, the rest of the algorithm was followed. The diagnosis of PE was considered ruled out if a patient met none of the three YEARS criteria and the d-dimer level was less than 1000 ng per milliliter, or if they met one or more of the criteria and the d-dimer level was less than 500 ng per milliliter. If PE was not ruled out, the patient underwent CT pulmonary angiography (CTPA).
In four patients, proximal deep venous thrombosis was diagnosed. Three of these had clinical signs of DVT and the fourth met both the criterion of PE as most likely diagnosis as well as d-dimer >1000. Acute PE was diagnosed in 16 patients on the basis of CTPA or V/Q scanning, 15 of whom met at least one YEARS criteria and had a d-dimer level above the threshold. The one patient diagnosed with PE who met none of the three YEARS criteria had a d-dimer above the pre-specified threshold. Patients in whom the diagnosis of PE was considered ruled out were then followed over a three month period, during which time none were diagnosed with PE. Even in a worst-case scenario, where all the patients who had been lost to follow-up during this period had developed a PE, the incidence among those not undergoing CTPA would have
been 0.42% (2 of 478 patients; 95% CI, 0.11 to 1.5).6 The results of the study showed that a pregnancy-adapted version of the YEARS algorithm was capable of safely ruling out PE in pregnant women who
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COMMON SENSE MAY/JUNE 2022
