Gravid Patient Protocol: Standard VTE algorithms (Wells, PERC) are invalidated by pregnancy. This pathway strictly utilises the LEFt rule for suspected DVT and the Pregnancy-Adapted YEARS algorithm for suspected PE to safely rule out thrombosis and minimise foetal radiation exposure.
1. Target Pathology
2. Clinical Evaluation
Sequential Diagnostic Output
Academic Pearls & Pathophysiology
1. Pathophysiology: Why the LEFT Leg?
Over 80% of deep vein thromboses during pregnancy occur in the left lower extremity. This is due to the anatomical compression of the left common iliac vein by the right common iliac artery and the expanding gravid uterus (May-Thurner anatomy exacerbated by pregnancy). This starkly contrasts with the non-pregnant population where DVT is equally distributed.
2. [CLINICAL PITFALL] D-Dimer in the 3rd Trimester
Practice Pearl: D-dimer levels naturally and progressively rise throughout a normal pregnancy due to physiologic hypercoagulability (preparation for placental separation). By the late 2nd and 3rd trimesters, D-dimer is often naturally elevated > 500 ng/mL. Therefore, attempting to rule out VTE using D-dimer late in pregnancy has a very low yield, and you will frequently be forced to proceed to imaging regardless.
3. Illness Scripts: Dyspnoea in Pregnancy
Pulmonary Embolism Presentation: Sudden onset dyspnoea, pleuritic chest pain, tachycardia out of proportion to baseline pregnancy elevation. Discriminator: Hypoxaemia. (Normal pregnancy causes hyperventilation but NOT hypoxaemia).
Physiologic Dyspnoea of Pregnancy Presentation: Gradual onset "air hunger", mostly in 3rd trimester. Patient feels they cannot take a deep breath. Discriminator: Normal O₂ saturation, normal lung exam, no sudden acute decompensation.
Peripartum Cardiomyopathy Presentation: Dyspnoea on exertion, orthopnoea, paroxysmal nocturnal dyspnoea appearing late in pregnancy or early postpartum. Discriminator: Basilar crackles, JVP elevation, peripheral oedema (bilateral).
Abbreviations: VTE (Venous Thromboembolism) · PE (Pulmonary Embolism) · DVT (Deep Vein Thrombosis) · CTPA (Computed Tomography Pulmonary Angiography) · V/Q (Ventilation/Perfusion Scan) · FEU (Fibrinogen Equivalent Units) · DDU (D-Dimer Units) · FOGSI (Federation of Obstetric and Gynaecological Societies of India)
Algorithm References & Evidence Base
Bistervels IM, et al. Pregnancy-Adapted YEARS Algorithm for Diagnosis of Suspected Pulmonary Embolism. N Engl J Med. 2019;380(12):1139-1149.
Righini M, et al. Clinical prediction rules for the diagnosis of deep vein thrombosis in pregnancy: The LEFt rule. Ann Intern Med. 2013;159(8):527-531.
FOGSI Good Clinical Practice Recommendations on Venous Thromboembolism in Pregnancy and Puerperium. Federation of Obstetric and Gynaecological Societies of India.
How to Cite This Tool
AMA Style: Umakanth S. Gravid VTE Exclusion Pathway. MEDiscuss. Published 2026. Accessed .
Vancouver Style: Umakanth S. Gravid VTE Exclusion Pathway [Internet]. MEDiscuss.org; 2026 [cited ]. Available from:
