Common signs and symptoms of colorectal cancer are influenced by the site of the primary tumor and may include a change in bowel habits, diarrhea, constipation, a feeling that the bowel does not empty completely, bright red blood in the stool or melanotic stools, and stools that are narrower in caliber than usual. Other signs include general abdominal discomfort (frequent gas pains, bloating, fullness, or cramps), weight loss for no known reason, fatigue, and vomiting. Findings that should prompt investigation for colon cancer include a rectal or abdominal mass, hepatomegaly, abdominal tenderness, or iron deficiency anemia. If one or more such findings are present, a full colorectal examination with colonoscopy should be done. However, the examination may be limited to sigmoidoscopy for rectal bleeding in most persons younger than 40 years of age because colorectal cancer is uncommon in such patients (except those with hereditary colorectal cancer syndromes), and in most young patients with hematochezia, a rectosigmoid lesion, usually hemorrhoids, is the cause of rectal bleeding. This patient is older than 40 years, has concerning symptoms, and therefore requires an immediate colonoscopy.