Background We present a rare complication of trans-sphenoidal adenectomy (TSA) for pituitary macroadenoma: carotid cavernous fistula (CCF) that was treated with endovascular therapy. The incidence of internal carotid artery (ICA) injury following TSA is 1% and may spontaneously heal by packing and rarely manifest as symptomatic CCF/aneurysm. Treatment of post-TSA CCF may be challenging due to the breach of nasal floor and may be prone to recurrence.

Presentation/intervention Uncontrolled intra-operative bleeding during a TSA led to an emergent angiogram to show slow-flow left CCF. Due to clinical deterioration with nasal bleeding, angiography was repeated after 4 h; the fistula had transformed into high flow with significant increase in size, and was therefore embolized using stent-assisted coiling. The fistula recanalized in a month with massive epistaxis and was re-treated using a covered stent graft.

Conclusion This case represents several unique learning points: (1) CCF as a complication of TSA due to close anatomical proximity; (2) the role of endovascular management post-TSA complication; (3) stent-assisted coil embolization of high-flow fistula with moderate ICA laceration; (4) recanalization of CCF causing massive epistaxis; (5) rare use of covered stent graft stent in distal intracranial circulation maintaining integrity and patency of ICA; (6) long-term results after covered stent graft with no in-stent restenosis.