Dynamic contrast-enhanced computed tomography for small bowel bleeding: Two cases of arteriovenous malformation and gastrointestinal stromal tumor

Small bowel bleeding is an uncommon cause of gastrointestinal hemorrhage and is often difficult to diagnose when upper and lower endoscopy fail to identify the bleeding source. Dynamic contrast-enhanced computed tomography (DCE-CT) has emerged as an important imaging modality for localizing lesions, estimating the underlying etiology, and guiding treatment strategies. We report two cases of small bowel bleeding with distinct etiologies: Arteriovenous malformation (AVM) and gastrointestinal stromal tumor (GIST). In the first case, DCECT demonstrated a mass-like lesion with intense arterial-phase enhancement comparable to adjacent arteries and early venous drainage, strongly suggesting a vascular lesion. Elective surgical resection was performed, and histopathological examination confirmed AVM. In the second case, CT revealed a well-defined mass with relatively persistent enhancement and contrast extravasation, indicating active bleeding from a neoplastic lesion. Due to hemodynamic deterioration, emergency surgical resection was required, and the lesion was diagnosed as GIST. These cases indicate that systematic evaluation of enhancement patterns and associated CT findings, including early venous drainage and contrast extravasation, can facilitate differentiation between vascular and neoplastic causes of small bowel bleeding and support appropriate treatment selection.