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SSc SIBO — SCE Rheumatology MCQ

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ModerateSystemic SclerosisSSc SIBOSCE Rheumatology

A 50-year-old woman with systemic sclerosis develops recurrent bloating, diarrhoea and malabsorption due to small intestinal bacterial overgrowth. Which pathophysiological process most directly predisposes to this complication?

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Correct answer: D — Small-bowel hypomotility and luminal stasis caused by enteric neuromuscular involvement

The correct answer is D. Gastrointestinal systemic sclerosis produces enteric neuromuscular dysfunction, including neural dysfunction and smooth-muscle atrophy with fibrosis. The resulting small-bowel hypomotility causes delayed transit and luminal stasis, allowing excessive bacterial proliferation and consequent bloating, diarrhoea and malabsorption. Proton pump inhibitors may modestly increase susceptibility by reducing gastric acid, but they are not the characteristic primary mechanism in systemic sclerosis. Immunosuppression is not the principal cause, while cholestasis may impair fat absorption without explaining typical SSc-associated SIBO. Accelerated transit would reduce, rather than promote, the stasis responsible for bacterial overgrowth.

Reference: Quigley EMM, McMahan ZH, Kulkarni S, Khanna D. Gastrointestinal Disorders in Scleroderma. Gastroenterology. Epub 15 April 2026. https://pubmed.ncbi.nlm.nih.gov/41997504/