S4642 A Gastroenteric Fistulation Preventing Peptic Ulcer Perforation

Introduction: Gastrointestinal (GI) fistulas are abnormal connections between the GI tract and an epithelialized surface, such as skin, bladder, or another section of GI tract. Common causes of GI fistulas include surgery, radiation, malignancy, inflammatory bowel disease (IBD), and diverticular disease. We present a case of an elderly woman with a fortuitous fistulation between the stomach and small bowel as a suspected complication from methotrexate toxicity causing a gastric ulcer. Case Description/Methods: A 73-year-old woman with a history of rheumatoid arthritis treated with methotrexate and gastroesophageal reflux disease presented as a transfer from an outside hospital (OSH) after presenting with 1 week of hematemesis and weakness. She had no known history of surgery, radiation, IBD, or cancer. Notably, the patient had been taking 25 mg of methotrexate daily rather than weekly as prescribed. She presented with a hemoglobin of 4.5 g/dL and underwent an esophagogastroduodenoscopy (EGD) that reportedly revealed concern for a large mass with underlying ulceration, which was biopsied. Biopsies were consistent with chronic inactive gastritis, negative for H. pylori from the ulcer base, and showed predominantly fragments of small bowel mucosa. She was found to have bilateral pulmonary embolisms after staging computed tomography scans and was started on anticoagulation but subsequently developed massive hematemesis. She was stabilized and transferred for inferior vena cava filter placement. Given concern for gastric malignancy from OSH, a repeat EGD showed a large non-malignant-appearing ulcer at the incisura with small bowel mucosa protruding through a fistula. The fistula was traversed with findings consistent with small bowel lumen and villous mucosa on the other side. Review of computed tomography abdomen suggested that the stomach fistulized to the proximal jejunum. In consultation with general surgery, the etiology of the fistula was thought to be secondary to methotrexate toxicity with possibility of spontaneous closure after cessation of methotrexate. The patient was discharged with plans for close follow-up and repeat EGD. Discussion: We report a rare case of a gastroenteric fistula secondary to gastric ulceration likely caused by methotrexate toxicity. The serendipitous location of the patient’s proximal jejunum may have saved the patient from an ulcer perforation in the abdominal cavity. This case emphasizes the need for doctors to regularly assess patients' understanding of treatment regimens.