Rectal Cancer

Symptoms & Detection

Your doctor may suggest one or more of the tests for rectal cancer detection listed below. These tests are used to detect polyps, cancer, or other abnormalities, even when a person does not have symptoms. Your health care provider can explain more about each test.

  • A fecal occult blood test (FOBT) is a test used to check for hidden blood in the stool. Sometimes cancers or polyps can bleed, and FOBT is used to detect small amounts of bleeding. A sample of stool is tested for traces of blood. People having this test will receive a kit with instructions that explain how to take stool samples at home. The kit is then sent to a lab for testing. If the test is positive, further tests will be done to pinpoint the exact cause of the bleeding.

  • A sigmoidoscopy is an examination of the rectum and lower colon (sigmoid colon) using a lighted instrument called a sigmoidoscope. A sigmoidoscope is a slender, lighted tube about the thickeness of a finger. It is placed into the lower part of the colon through the rectum. This allows the doctor to look at the inside of the rectum and part of the colon for cancer or polyps. Because the tube is only about 2 feet long, the doctor is only able to see about half of the colon. The test can be uncomfortable but it should not be painful. Before the test, you will need to take an enema to clean out the lower colon.

  • A colonoscopy is an examination of the rectum and entire colon using a lighted instrument called a colonoscope, a longer version of the sigmoidoscope. It allows the doctor to see the entire colon. If a polyp is found, the doctor may remove it. If anything else looks abnormal, a biopsy might be done. To do this, a small piece of tissue is taken out through the colonoscope. The tissue is sent to the lab to see if cancer cells are present. This test can be uncomfortable. To avoid this, you will be given medicine through a vein to make you feel relaxed and sleepy.

  • A virtual colonoscopy is like a super x-ray of the colon. Air is pumped into the colon to cause it to expand, then a special CT scan is done. More studies are needed to find out if it is as good as or better than other methods of finding colon cancer early.

  • A double contrast barium enema (DCBE) is a series of x-rays of the colon and rectum. A chalky substance is used to partly fill and open up the colon. Air is then pumped in to cause the colon to expand. This allows good x-ray films to be taken. You will need to use laxatives the night before the exam and have an enema the morning of the exam.

  • A digital rectal exam (DRE) is an exam in which the doctor inserts a lubricated, gloved finger into the rectum to feel for abnormal areas.

Recognizing Rectal Cancer Symptoms

Common signs and symptoms of colorectal cancer include:

  • A change in bowel habits
  • Diarrhea, constipation, or feeling that the bowel does not empty completely
  • Blood (either bright red or very dark) in the stool
  • Stools that are narrower than usual
  • General abdominal discomfort (frequent gas pains, bloating, fullness, and/or cramps)
  • Weight loss with no known reason
  • Constant tiredness
  • Vomiting

Most often, these symptoms are not due to rectal cancer. Other health problems can cause the same symptoms. Anyone with these potential rectal cancer symptoms should see a doctor so that any problem can be diagnosed and treated as early as possible.

Usually, early rectal cancer does not cause pain. It is important not to wait to feel pain before seeing a doctor

We care about your feedback. Let us know how we can improve your CancerCompass experience.