(Gastrointestinal and Liver Center) article author : Tiwaporn Thummongkhol, M.D.



Colorectal cancer is the most common cancer in Thailand and steadily continues to increase the incidence rate.


Colorectal cancer is a disease in which cells in the colon or rectum grow out of control. The abnormal growths will form in the colon or rectum and may turn into cancer. Nowadays, screening can helps find colorectal cancer at an early stage through colonoscopy.


Who should get a colonoscopy?

1. Constipation, diarrhea, and diarrhea or constipation that lasts for several days

2. Rectal bleeding, dark-colored stool

3. Blood in your stool

4. Abdominal cramps or pain, flatulence

5. Unintended weight loss, abdominal mass

6. Ulcerative colitis

7. Have a family history of colorectal cancer

8. Age 45 or older should do the colorectal cancer screening test


What is a colonoscopy?

Colonoscopy is a procedure that uses a colonoscope to look inside the large bowel and the distal part of the small bowel, which is a long, flexible tube about the width of a finger. It’s put in through the anus and into the rectum and colon.


How long does a colonoscopy take?

The procedure typically takes 30-60 minutes, depending on the doctors' need to remove polys or take biopsies.


Colonoscope preparation is as below details:

1. Avoid high-fiber foods such as vegetables and fruits for a few days.

2. Clear liquid diet for the entire day before the procedure such as; fish, egg, porridge, etc.

3. Take a laxatives tablet. Taking a base on procedure setting time:

  • In the morning: Must take laxative tablets 1 day in advance.
  • In the afternoon: Can take laxative tablets in the morning for clean bowel and the stool will be clear, light, and liquid 2 hours before the procedure.

4. Necessary to stop eating and drinking anything for 6-8 hours except water before performing a colonoscope for 2 hours.

5. Stop anticoagulant for 3-7 days (depending on medication and dose) or doctor's order.


How do we know the bowel preparation is clear?

By the end of preparation, your stool should become a clear, yellow-tinged fluid.


How painful is a colonoscopy?

A colonoscopy is usually done by sedating the patient so that doesn’t feel pain will help to block pain and make you comfortable.


Colonoscopy recovery

Usually must stay at the center for an hour after recovery from the sedative and then can go home under the care of family members or good friends.


The results of the colonoscopy

After the procedure, the general results can be shown. If had a biopsy or had polys removed will wait for the result 7 days.

1. Can drink water or other beverages and by eating liquid-based food for 1 day.

2. Observe your stool, might be bleeding

3. Advise to avoid driving and operating machinery, or power tools for at least 24 hours

4. If after colonoscopy severe abdominal pain, fever, or dizziness should consult the doctor immediately.

5. Usually the patient can go home after an hour except the patient get a biopsy or polys removed must be observed at the hospital for 1 day.


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