Diagnosis at Mayo Clinic

By Mayo Clinic Staff


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Screening for cancer with colon cancer screening tests can also detect rectal cancer. Screening tests may identify rectal cancer before it begins or at its earliest stages, when successful treatment is more likely.

If your doctor suspects you may have rectal cancer or signs of cancer have been detected during a screening test, you may undergo additional tests, such as:

  • Proctosigmoidoscopy. During a proctosigmoidoscopy exam, your doctor uses a long, thin tube equipped with a camera to examine your rectum and the lower part of your colon. This allows your doctor to evaluate the size of your rectal cancer and to collect a sample of cells for laboratory testing.
  • Endorectal ultrasound. Once your rectal cancer is confirmed, your doctor may recommend an ultrasound exam of your rectum. This is done using a thin probe that emits sound waves to create images. An endorectal ultrasound can help your doctor understand how deep the cancer extends into the wall of the rectum.
  • Colonoscopy. During a colonoscopy exam, your doctor uses a long, thin tube equipped with a camera to examine the inside of your rectum and your entire colon. Sometimes colon cancer and rectal cancer can occur at the same time. So your doctor may want to examine all of your large intestine for signs of cancer.
  • Imaging tests to look for cancer spread. Rectal cancer can spread (metastasize) to other areas of the body, such as the liver and the lungs. You may undergo imaging tests to look for signs that cancer has spread, such as an X-ray, CT scan, MRI and positron emission tomography (PET) scan.

Which tests you undergo will depend on your individual situation

Feb. 26, 2015