Case Report: Complicated Meckel's diverticulum masquerading as gastroenteritis: a near-fatal presentation in a toddler.

Background: Meckel's diverticulum poses diagnostic difficulties due to its nonspecific symptoms, which often resemble benign conditions like gastroenteritis. Case presentation: A 2-year-11-month-old girl presented with abdominal pain and vomiting, initially diagnosed as acute gastroenteritis. Within 12 h, her condition deteriorated rapidly with fever, lethargy, and circulatory shock. Laboratory findings included marked leukocytosis (36.05 × 10⁹/L), severe metabolic acidosis (pH 7.32, HCO₃⁻ 5.2 mmol/L), and elevated lactate (3.3 mmol/L). Emergency abdominal CT showed small bowel obstruction with a mid-abdominal mass and significant ascites. Emergency laparotomy revealed a strangulated Meckel's diverticulum with ileal necrosis, requiring segmental bowel resection. The postoperative course was complicated by refractory septic shock, septic cardiomyopathy, and multiple organ dysfunction syndrome, necessitating advanced support including mechanical ventilation, continuous renal replacement therapy, and plasma exchange. Conclusion: This case highlights the potential for rapid clinical deterioration in children with surgically correctable abdominal pathologies that initially appear benign. Recognizing red flags-such as rapid systemic toxicity, disproportionate metabolic acidosis, and abdominal distension-is essential to prompt immediate surgical evaluation and prevent catastrophic outcomes.