Radiation, Microscopic, and Ischemic Colitis

This episode unpacks three deceptive colitis presentations. For chronic radiation proctitis, driven by obliterative endarteritis, the biggest takeaway is strictly avoiding mucosal biopsies to prevent catastrophic fistulas. Microscopic colitis (collagenous and lymphocytic) presents with watery diarrhea and normal gross mucosa, requiring specific targeted biopsies and treatment with budesonide. Finally, ischemic colitis is detailed as a low-flow microvascular event causing superficial necrosis with deep crypt sparing, where primary anastomosis is contraindicated in the acute setting.