A 70-year-old with a 5.8 cm infrarenal abdominal aortic aneurysm undergoes endovascular aneurysm repair (EVAR). Post-procedure CT angiogram at 12 months shows persistent contrast within the aneurysm sac after the endograft is deployed, without a graft defect. The contrast enters the sac from the inferior mesenteric artery origin (IMA) which was covered by the graft proximally but fills retrogradely from the internal iliac collaterals. This is classified as:

• A Type II endoleak — retrograde flow into the aneurysm sac from a patent side branch (IMA or lumbar arteries) ✓
• B Type I endoleak — attachment site leak at the proximal or distal seal zone
• C Type III endoleak — device failure (graft fabric tear or modular junction disconnection)
• D Type IV endoleak — graft porosity during the periprocedural period

Explanation

Endoleaks are classified by source: Type I = seal zone leak (proximal Ia or distal Ib — most dangerous, requires urgent treatment); Type II = retrograde filling from aortic side branches (IMA, lumbar arteries — most common, often managed conservatively but treated if sac enlarges); Type III = graft component separation or fabric defect; Type IV = graft fabric porosity (early, self-limiting). The IMA filling retrogradely from internal iliac collaterals into the sac is the definition of a Type II endoleak.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.