Isolated Rectal Wall Necrosis Presenting with Septic Shock: A Rare Manifestation of Non-Occlusive Ischaemia.

Introduction: Acute rectal ischaemia is an exceptionally rare but life-threatening condition because the rectum is usually protected by its rich collateral blood supply. Isolated rectal wall necrosis is particularly uncommon and may present a major diagnostic challenge, especially in critically ill patients. Case description: A 45-year-old male presented with a three-day history of progressive diffuse abdominal pain and profound haemodynamic instability. On admission, he was hypotensive (70/50 mmHg) and showed signs of generalised peritonitis. Laboratory investigations revealed leukopenia and acute kidney injury. Computed tomography demonstrated free intraperitoneal air, most prominent along the anterior rectal wall, with suspected perforation below the peritoneal reflection and intramural gas extending above it, along with the presence of free intraperitoneal fluid. An emergency laparotomy revealed faecal peritonitis and extensive transmural necrosis of the anterior rectal wall with perforation in the mid-rectum below the peritoneal reflection. Necrosis extended to and involved the peritoneal reflection and rectovesical pouch, without evidence of malignancy, diverticular disease or mechanical obstruction. A low Hartmann's procedure was performed. Postoperatively, the patient required intensive care and vasopressor support but gradually improved. Bowel continuity was later restored, with satisfactory functional recovery. Conclusion: This case demonstrates that isolated rectal wall necrosis secondary to non-occlusive ischaemic injury may progress to perforation, faecal peritonitis and septic shock, even in the absence of classical local predisposing factors. Early recognition and prompt source control are essential for survival. LEARNING POINTS: Isolated rectal ischaemia is exceptionally rare but should be considered in critically ill patients presenting with abdominal pain, septic shock and signs of peritonitis or bowel perforation.Non-occlusive mesenteric ischaemia may involve even well-perfused segments such as the rectum, as mesenteric vasoconstriction leads to severe splanchnic hypoperfusion and rapid progression to transmural necrosis and perforation.In haemodynamically unstable patients, CT findings may underestimate the extent of ischaemic bowel injury; early recognition and prompt source control are crucial for survival.