On CT pulmonary angiography (CTPA), which finding in the main pulmonary artery reliably indicates massive (central) pulmonary embolism with high haemodynamic risk?

• A Unilateral small pleural effusion
• B A 'saddle embolus' straddling the bifurcation of the main pulmonary artery ✓
• C A peripheral wedge-shaped opacity (Hampton's hump) on the same study
• D Mild enlargement of a single segmental pulmonary artery

Explanation

A saddle embolus is a large thrombus straddling the bifurcation of the main pulmonary artery, simultaneously obstructing both pulmonary arteries. This constitutes massive central PE associated with haemodynamic compromise, high mortality, and is an indication for thrombolysis or surgical embolectomy. Hampton's hump (peripheral wedge opacity abutting pleura = pulmonary infarct) is a complication but not a measure of PE magnitude. Unilateral effusion is a non-specific finding. Segmental artery involvement indicates submassive or segmental PE.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.