下消化道由于肠道长 ,病变隐匿 ,引起出血的病变多 ,尤其大肠及回肠末端是血管瘤、肿瘤、结核 (ＴＢ)、炎性肠病 (ＩＢＤ )、淋巴瘤等出血性疾病的好发部位。出血不但与病变侵蚀血管破裂有关 ,而且还与肠腔内压力 ,肠管蠕动 ,血压及凝血机制等诸多因素有关 ,故给诊断带来较大困 Lower gastrointestinal tract due to intestinal long, hidden lesions, causing bleeding more lesions, especially the large intestine and ileum is hemangioma, tumor, tuberculosis (TB), inflammatory bowel disease (IBD), lymphoma and other bleeding disorders are good Site. Bleeding is not only associated with vascular lesions of vascular erosion, but also with the intestinal cavity pressure, intestinal peristalsis, blood pressure and coagulation mechanisms and many other factors, so to the diagnosis of greater difficulties