Acute ischaemic colitis most commonly affects which segment of the colon and is related to which anatomical watershed zone?

• A Sigmoid colon at the junction of IMA and pudendal artery territories
• B Hepatic flexure — watershed between celiac and SMA territories
• C Transverse colon at the marginal artery of Drummond midpoint
• D Splenic flexure — watershed between SMA (middle colic) and IMA (left colic) territories ✓

Explanation

The splenic flexure is the classic watershed zone between the territory of the SMA (middle colic artery branch) and IMA (left colic artery), making it the most vulnerable segment to ischaemia during systemic hypoperfusion or after aortic surgery. The rectosigmoid is another watershed (IMA vs internal iliac/superior rectal artery) and is at risk after IMA ligation during aortic repair. Clinical presentation is left-sided bloody diarrhoea with CT showing thumbprinting.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.