From Septic Shock to Hemorrhagic Shock: A Rare Presentation of Ischemic Rectal Ulcer in a Critically Ill Patient

Acute hemorrhagic rectal ulcer (AHRU) is an uncommon but clinically significant cause of lower gastrointestinal bleeding in critically ill patients. While stress-related mucosal disease is a well-recognized cause of upper gastrointestinal bleeding in the intensive care unit (ICU), ischemic injury involving the rectum is less frequently reported. Patients recovering from septic shock, particularly those requiring prolonged vasopressor therapy, remain at risk for delayed ischemic complications. We present a case of delayed severe lower gastrointestinal bleeding due to AHRU following septic shock, highlighting the risk of ischemic complications even after apparent clinical stabilization. A 54-year-old man with insulin-dependent type 2 diabetes mellitus presented with severe diabetic ketoacidosis and was admitted to the ICU. His course was complicated by methicillin-sensitive Staphylococcus aureus pneumonia and septic shock requiring prolonged vasopressor support. After initial clinical improvement and transfer out of the ICU, he developed acute hematochezia with a significant decline in hemoglobin. Computed tomography angiography demonstrated active rectal bleeding. Flexible sigmoidoscopy revealed multiple rectal ulcers consistent with AHRU. Although hematin and ulcerated mucosa with stigmata of recent bleeding were identified in the rectosigmoid region, the ulcers were not actively bleeding at the time of the procedure, and no endoscopic hemostatic intervention was performed; lavage was performed to improve visualization. His condition deteriorated with hemorrhagic shock requiring reintubation, vasopressor support, and massive transfusion protocol. Following multidisciplinary management, he stabilized and was ultimately discharged to a rehabilitation facility. This case is notable for the delayed onset of severe lower gastrointestinal bleeding due to AHRU following apparent recovery from septic shock, highlighting a temporal gap between hemodynamic insult and clinical manifestation. Unlike typical stress-related mucosal disease, which primarily affects the upper gastrointestinal tract, AHRU represents a less recognized form of ischemic injury involving the rectum, likely driven by prolonged splanchnic hypoperfusion and vasopressor-induced vasoconstriction. The severity of bleeding requiring massive transfusion and critical care re-escalation underscores the potential for rapid clinical deterioration. This case emphasizes the importance of maintaining a high index of suspicion for ischemic rectal injury in post-ICU patients with new-onset hematochezia, even after initial stabilization. This case highlights a rare and delayed ischemic complication of septic shock. AHRU should be considered in critically ill patients with new-onset lower gastrointestinal bleeding, particularly following prolonged vasopressor use. Current stress ulcer prophylaxis strategies may not prevent such complications, emphasizing the need for broader preventive approaches targeting splanchnic perfusion, bowel care, minimization of prolonged rectal device use, and early recognition of ischemic lower gastrointestinal injury.