Treatment protocol used at our institution for the embolization of idiopathic posterior epistaxis

Step	Action	Clarification
1	Angiogram of il^* ICA	Verify supply to the OphA and choroidal blush from the ICA; rule out an ICA source of bleeding; check for extensive supply to nasal mucosa from the EAs
2	Angiogram of il ECA	Rule out vascular anomalies; check for dangerous anastomoses between ECA and ICA; rule out nonidiopathic causes of epistaxis
3	Embolization of il IMA	Selective catheterization of IMA, distal to MDTA, and embolization with suspension of PVA particles (250–350 μm) in contrast medium; sometimes followed by 1 or 2 Gelfoam pledgets
4	Embolization of il FA	Performed if significant supply to nasal mucosa from FA; selective catheterization of FA, distal to SMA, and embolization with suspension of PVA particles (250–350 μm) in contrast medium
5	Repeat 1–4 on cl^* side	Due to collaterals between il and cl vasculature, we routinely include the cl side in our protocol
6	Transfer to ENT department	The packs are usually removed the following day by the ENT department

Note:—il indicates ipsilateral; cl, contralateral; ENT, ear-nose-throat; EAs: ethmoidal arteries (anterior and posterior); ICA, internal carotid artery; OphA, ophthalmic artery; ECA, external carotid artery; IMA, internal maxillary artery; MDTA, middle deep temporal artery; PVA, polyvinyl alcohol; FA, facial artery; SMA, submandibular artery.
* il and cl indicate the side of bleeding or, if the patient bleeds from both nostrils, the side where bleeding started.