The evaluation of colorectal cancer begins with a medical history and physical examination.

The physical examination may be normal in someone with colorectal cancer.

Physical findings in someone with colorectal cancer may include:

• A mass or nodule may be felt on rectal examination.
• The stool may contain blood
• Muscle wasting and malnutrition

The diagnosis of colorectal cancer must be confirmed through testing.

Tests that may be used to evaluate colorectal cancer include:

• Stool guaiac:
• Testing stools for the presence of blood not visible to the naked eye
• DNA stool testing:
• A test that looks for abnormal DNA in a stool sample.
• Complete blood count
• Liver profile
• Kidney profile
• Urinalysis
• Anoscopy
• Colonoscopy:
• Allows a doctor to look inside, take tissue specimens, and remove any questionable growths or polyps.
• Sigmoidoscopy:
• Allows a doctor to look inside, take tissue specimens, and remove any questionable growths or polyps.

Imaging studies that may be used to evaluate colorectal cancer include:

• Barium enema
• CT scanning of the abdomen: an excellent test for excluding internal injury
• MRI scan of the abdomen
• Virtual colonoscopy:
• Uses a special type of CT scanner that takes many pictures of the colon in super thin slices. A computer reassembles the images into a 3-D model of the colon. The more slices the CT scanner is capable of taking in rapid succession, the better the image quality.
• Bone scanning