A 58-year-old man becomes hypotensive with left flank pain and a falling haematocrit four hours after a technically difficult femoral arterial catheterization in which the puncture was made higher than intended. CT shows a large haematoma extending into the posterior pararenal space. Which mechanism best explains this complication?

• A Puncture of the superficial femoral artery distal to the profunda branch
• B Puncture above the inguinal ligament, allowing uncontained retroperitoneal haemorrhage ✓
• C Formation of an arteriovenous fistula between the femoral vessels
• D Guidewire-induced dissection of the common iliac artery

Explanation

The femoral head provides a firm bony backing that allows effective manual compression of a correctly sited puncture below the inguinal ligament. When the artery is entered above the ligament, the posterior wall of the vessel lies against soft tissue with no bone behind it, so blood tracks freely into the retroperitoneum and cannot be compressed externally, producing delayed hypotension and flank pain. Arteriovenous fistula and dissection present differently and do not produce this pattern of uncontained haemorrhage.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.