Renoduodenal fistula caused by a large staghorn calculus revealed on endoscopy

We present a rare case of an 83-year-old Asian woman referred for a gastroscopy due to 6 months of epigastric discomfort, nausea and a 5 kg weight loss. Her blood work revealed mild anemia with a hemoglobin of 9.0 g/dL, mild renal impairment with an estimated glomerular filtration rate of 40 (normal range is 90 or higher), and normal inflammatory markers. Endoscopy revealed significant distortion due to mucosal erythema and edema in the second part of the duodenum (Figs. 1, 2, and 3), hindering scope advancement.