Severe Upper Gastrointestinal Bleeding in a 12-Year-Old Boy with Acute SARS-CoV-2 Infection Complicating Perforated Appendicitis: A Case Report and Differential Considerations

Background: Gastrointestinal (GI) involvement is increasingly recognised in paediatric SARS-CoV-2 infection and multisystem inflammatory syndrome in children (MIS-C), but severe GI bleeding remains rare. Its pathogenesis in this setting is multifactorial: direct viral injury, hyperinflammatory microvascular damage, treatment-related mucosal injury, and coagulopathy may all contribute, and the relative role of each is often difficult to disentangle. Case Presentation: A previously healthy 12-year-old boy underwent appendectomy for perforated appendicitis with peritonitis. On postoperative Day 1, he developed high fever and was found to be SARS-CoV-2 PCR-positive; SARS-CoV-2 IgM and IgG were also positive. He met the positive clinical elements of the CDC 2023 case definition for MIS-C (persistent fever, multisystem involvement—gastrointestinal, hepatic, haematological, and markedly elevated inflammatory markers), although perforated appendicitis with peritonitis is a sufficient alternative explanation and the diagnosis cannot be regarded as secure (see Discussion). Treatment included broad-spectrum antibiotics (meropenem, amikacin, metronidazole), methylprednisolone 2 mg/kg/day, and intravenous immunoglobulin (IVIG) 2 g/kg. On Day 4 in the paediatric intensive care unit (PICU), the patient developed sudden haematemesis with fresh blood through the nasogastric tube and haemodynamic collapse. Coagulation studies revealed prolonged INR (1.6) and reduced prothrombin activity (42%). The patient was stabilised with packed red blood cells, fresh frozen plasma, and intravenous vitamin K. Fibrogastroscopy demonstrated diffuse mucosal bleeding without ulcers or anatomical defects; histology showed mucosal hyperaemia, mixed basal inflammation with intraepithelial lymphocytes, and small erosions. Melena persisted for several days. The child recovered fully and was discharged after 20 days with substantially improved but not fully normalised laboratory values (residual mild anaemia, Hb 110 g/L, and elevated CRP 32.7 mg/L and D-dimer 5.88 mg/L). Conclusions: Severe upper GI bleeding is a rare but life-threatening event in children with severe SARS-CoV-2 infection and MIS-C. In our case, several mechanisms may have acted in combination, although none could be confirmed individually: possible direct viral enterocyte injury via ACE-2 receptors, hyperinflammatory microangiopathy, high-dose corticosteroid-related mucosal injury, possible broad-spectrum antibiotic-associated vitamin K deficiency, and postoperative critical-illness stress. Their relative contributions cannot be determined from a single retrospective case. Bleeding occurred despite continuous PPI prophylaxis, suggesting that PPI cover alone is insufficient when multiple risk factors coexist; the clinical implication is that risk-factor-based (rather than universal) PPI prophylaxis, together with monitoring of vitamin K-dependent coagulation, should be considered in critically ill children receiving high-dose corticosteroids and prolonged broad-spectrum antibiotics.