A 62-year-old man with a history of hypertension and chronic aspirin use presents with severe epistaxis. Anterior rhinoscopy shows no obvious bleeding site. Endoscopic examination reveals bleeding from the posterolateral nasal cavity. What is the most common cause of posterior epistaxis in adults?

Explanation

## Posterior Epistaxis — Etiology and Hemodynamics **Key Point:** Sphenopalatine artery (SPA) bleeding is the most common cause of posterior epistaxis, accounting for the majority of severe, recurrent epistaxis cases requiring intervention. ### Sphenopalatine Artery — Anatomy & Pathophysiology The sphenopalatine artery is the terminal branch of the maxillary artery (itself a branch of the external carotid). It enters the nasal cavity through the sphenopalatine foramen and supplies: - **Posterolateral nasal wall** - **Posterior nasal septum** - **Posterior turbinates** ### Why SPA Bleeding Causes Severe Epistaxis | Feature | Anterior (Kiesselbach's) | Posterior (SPA) | |---------|--------------------------|----------------| | **Frequency** | 90% of epistaxis | 5–10% of epistaxis | | **Severity** | Usually self-limiting | Often severe, recurrent | | **Presentation** | Blood from nostrils | Blood in pharynx, hemoptysis | | **Vessel caliber** | Small capillary plexus | Large artery (3–5 mm) | | **Transfusion need** | Rare | Common | | **Intervention rate** | <5% | >50% | ### Risk Factors for SPA Bleeding **High-Yield:** Posterior epistaxis is more common in: - **Older adults** (>60 years) — atherosclerosis, hypertension - **Anticoagulation / antiplatelet therapy** — aspirin, warfarin, DOACs - **Hypertension** — vessel wall stress - **Coagulopathy** — hemophilia, thrombocytopenia - **Nasal trauma or surgery** — iatrogenic vessel injury ### Management Algorithm for Posterior Epistaxis ```mermaid flowchart TD A[Posterior Epistaxis<br/>SPA Bleeding]:::outcome --> B{Hemodynamically stable?}:::decision B -->|Yes| C[Topical vasoconstrictor<br/>+ Hemostatic agent]:::action B -->|No| D[IV access, fluid resuscitation<br/>Cross-match blood]:::action C --> E{Bleeding controlled?}:::decision D --> F[Posterior packing or<br/>Endoscopic SPA ligation]:::action E -->|Yes| G[Admit for observation<br/>Remove pack in 48–72 hrs]:::outcome E -->|No| F F --> H[Definitive hemostasis<br/>Consider angiography if recurrent]:::action ``` **Clinical Pearl:** Posterior packing (traditional Foley balloon or specialized packs) is increasingly being replaced by **endoscopic sphenopalatine artery ligation (ESPAL)**, which has higher success rates (>95%) and lower morbidity than posterior packing. **Mnemonic:** **SPA-POSTERIOR** — **S**phenopalatine artery causes **P**osterior epistaxis in older, hypertensive patients on **A**ntiplatelet agents. [cite:Scott-Brown's Otolaryngology 8e Ch 23]