Histologically confirmed sodium polystyrene sulfonate-associated small bowel ischaemia after redo valve surgery

Ischaemic bowel remains one of the most serious complications following cardiac surgery, with mortality rates reaching up to 70%. Sodium polystyrene sulfonate (SPS), particularly when administered with sorbitol, has been linked to intestinal ulceration and necrosis, especially in patients with renal impairment. We describe a rare case of small bowel ischaemia attributed to SPS use in a 72-year-old woman with chronic kidney disease who underwent redo double valve replacement with septal myectomy. Her postoperative course was complicated by acute kidney injury and hyperkalaemia, for which a single dose of rectal SPS was administered. Within hours, she developed severe abdominal pain and raised lactate levels. Computed tomographic mesenteric angiography revealed pneumatosis intestinalis and portal venous gas. Emergency laparotomy identified a 5-cm segment of necrotic small bowel, which was resected. Histopathology confirmed diffuse ischaemic changes with kayexalate crystals embedded in the bowel wall, establishing a causal link to SPS. The patient’s recovery was protracted and complicated by stroke and pneumonia, but she was ultimately discharged in stable condition. This case highlights a rare, clinically important postoperative hazard and supports avoiding routine rectal SPS in vulnerable cardiac surgical patients. SPS-associated gastrointestinal injury after cardiac surgery can mimic postoperative mesenteric ischaemia and may involve the small bowel, not only the colon. Temporal onset after SPS exposure and kayexalate crystals within the injured bowel support SPS as a proximate contributor, but patient-specific low-flow and comorbidity factors must also be acknowledged. In high-risk post-cardiac surgery patients, treat hyperkalaemia with rapid temporising therapies and early CKRT or dialysis; reserve SPS for selected non-emergent situations and maintain a low threshold for CT imaging and surgical review.