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Colorectal Cancer Screening Tests

Colorectal cancer is treatable when detected early. Screening tests can find colorectal cancers at an early stage when treatment is the most successful. Screening tests can also help prevent some cancers by allowing doctors to find and remove polyps that might become cancer.

The American Cancer Society recommends the following tests for men and women of average risk. Screening should begin at age 50.



Colonoscopies should be done every 10 years, beginning at age 50.

This procedure looks inside the rectum and colon for polyps, abnormal areas, or cancer. A colonoscope (a thin, lighted tube) is inserted through the rectum into the colon. Polyps or tissue samples may be taken for biopsy. You will receive sedation, and are not awake, during this procedure.

Colonoscopy, considered the "gold standard" of colon cancer screening, is among the most-frequently performed endoscopic procedures. Its purpose is trifold - diagnostic, preventative and interventional. A colonoscopy gets to the bottom of troublesome gastrointestinal symptoms, screens for diseases of the colon and removes precancerous lesions. If necessary, small biopsies may be taken and sent to pathology.

Why it's recommended

Colon cancer is preventable and curable if caught early. Regular screening via colonoscopy is recommended every 5-10 years beginning at age 50, earlier if there's family history. It's generally believed that colon cancer takes longer than 10 years to grow, so if you have a family history of colon cancer in a first degree relative, a guideline is to schedule your first colonoscopy when you are 40 years old or 10-years younger than the age of your family member's diagnosis, whichever comes first.

How to prepare

Since colonoscopies are visual in nature, it's essential that patients comply with pre-procedure prep. This involves a liquid diet the day before the test, followed by a prescription laxative and/or bowel cleanse.

What to expect

Upon registration, you will be taken to a pre-op bay, where a nurse will take your vital signs and start an intravenous line. In the procedure room, you will be positioned comfortably on your left side. You will be administered a sedative or light anesthetic. An endoscope is then inserted through the anus. The physician maneuvers the endoscope through the twists and turns of the colon. The procedure usually takes less than 30 minutes.

What happens next

Upon awaking in a recovery bay, you won't have any recollection of the procedure and might feel a little 'foggy' from the sedation/anesthesia. Since the procedure often requires the doctor to inflate the colon   with air, you may experience mild stomach cramps and the need to pass gas.

It's mandatory that a companion be available to drive you home. Preliminary results may be discussed, and if necessary, a follow-up appointment with any physician on Memorial Herman's multi-disciplinary team may be scheduled. 

Other Screening Options

Stool blood tests - Fecal occult blood test (FOBT) or fecal immunochemical test (FIT): Annually, beginning at age 50
This test checks stool (solid waste) for blood that can only be seen with a microscope.

Barium enema: Every five years, beginning at age 50
This is a series of X-rays of the lower gastrointestinal tract. A liquid that contains barium (a silver-white metallic compound) is put into the rectum. The barium coats the lower gastrointestinal tract and X-rays are taken. This procedure is also called a lower GI series.

Flexible Sigmoidoscopy: Every five years, beginning at age 50
This procedure looks inside the rectum and sigmoid (lower) colon for polyps, abnormal areas, or cancer. A sigmoidoscope (a thin, lighted tube) is inserted through the rectum into the sigmoid colon. Polyps or tissue samples may be taken for biopsy.

Yearly stool blood test plus Flexible Sigmoidoscopy: Every five years, beginning at age 50

Symptoms of Colorectal Cancer

Sometimes there are no symptoms of colorectal cancer in its early stages. However, talk to your doctor as soon as possible if you notice anything unusual.

  • Change in bowel habits, including constipation, diarrhea or change in stool consistency
  • Blood in the stool
  • Abdominal pain with a bowel movement
  • Persistent cramps, gas, bloating or abdominal pain
  • Feeling that the bowel doesn't empty completely
  • Unexplained weight loss