Pneumoperitoneum following revision hip arthroplasty without hollow viscus perforation: a gastrointestinal surgical diagnostic challenge and the importance of clinical-radiological correlation.

Pneumoperitoneum typically suggests hollow viscus perforation and often prompts urgent laparotomy. However, non-visceral causes should be considered, particularly postoperatively, where instrumentation may introduce air into unexpected compartments. Misinterpretation can result in unnecessary surgery and avoidable morbidity.We report a woman in her 50s who developed pneumoperitoneum following revision hip arthroplasty for prosthetic joint infection. She had elevated inflammatory markers but a soft, non-tender abdomen. Blood tests showed white cell count 34.0×109/L, C-reactive protein 84 mg/L, haemoglobin 99 g/L, albumin 16 g/L and lactate 1.9 mmol/L. CT revealed large pneumoperitoneum without bowel defect, contrast leak, pneumatosis, portal venous gas or collection. Gas tracked from the acetabulum along the iliopsoas into the retroperitoneum, demonstrating continuity with the operative site.Multidisciplinary review concluded the air likely originated from the hip, possibly related to high-pressure pulse lavage and medial acetabular wall thinning. She was managed conservatively without laparotomy.