ABSTRACT
Objective To study the etiology,relevant factors and endoscopic characteristics of acute lower gastrointestinal tract hemorrhage.Methods A total of 938 patients receiving emergency colonoscopy for acute lower gastrointestinal tract hemorrhage were collected to study the etiological profiles.Different causes between young group and elderly group were also recorded.Results The total detectable rate of acute lower gastrointestinal tract hemorrhage in respect of causes was 96.16％ (902/938).The five leading causes were colorectal malignancy (41.26％),erosive colorectal polypus (12.37％),inflammatory bowel disease (9.59％),erosive and ulcer colitis (10.34％) and hemorrhoids (8.64％).Compared with youth and middle age patients,the incidence of colorectal malignancy (x2 =68.116,df =2,P =0.000) and colorectal polyps (x2 =9.101,df =2,P =0.011) were significantly increased in elderly patients,while incidence of inflammatory bowel disease (x2 =62.150,df=2,P =0.000) and erosive and ulcer colitis (x2 =20.292,df =2,P =0.000) were significantly decreased in those patients.Conclusions Emergency colonoscopy for diagnosis of acute lower gastrointestinal tract hemorrhage is an important measure.The major manifestation is bleeding resulting from colorectal malignancy,erosive colorectal polypus,inflammatory bowel disease,erosive and ulcer colitis and anal hemorrhoid.Age is associated with the cause of lower gastrointestinal tract bleeding induced by different kinds of lesions at the colorectum.