Unexpected para-aortic venous migration of n-butyl cyanoacrylate during transarterial sac embolization for a type II endoleak: A technical pitfall.

We report an unusual case of para-aortic venous migration of n-butyl cyanoacrylate (NBCA) during transarterial sac embolization for a type II endoleak after endovascular aneurysm repair. Preprocedural computed tomography and angiography demonstrated no venous communication. During progressive NBCA injection, sequential opacification of the fourth lumbar vein and a para-aortic venous structure became apparent, prompting immediate cessation of embolization. The patient remained asymptomatic, and follow-up imaging demonstrated stable aneurysm size without complications. This case highlights a rare technical pitfall and emphasizes careful fluoroscopic monitoring during NBCA sac embolization despite initially negative imaging findings.