A 68-year-old man with atrial fibrillation develops sudden left-sided abdominal pain and bloody diarrhoea. Colonoscopy shows mucosal oedema and subepithelial haemorrhage with sparing of the rectum. Which segment of the colon is most vulnerable to this process and represents the classic watershed area?

• A Caecum
• B Splenic flexure ✓
• C Ascending colon
• D Hepatic flexure

Explanation

Ischaemic colitis preferentially strikes watershed zones with tenuous collateral supply. The splenic flexure, called Griffith's point, sits at the junction of the terminal branches of the superior and inferior mesenteric arteries and is the classical site. The rectum is characteristically spared because of its dual supply from the superior, middle and inferior rectal arteries, which explains the normal findings distally and eliminates the distal options.

Reference: Sabiston Textbook of Surgery, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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