Colonoscopy

What it is

Colonoscopy is an examination of the rectum and the whole large bowel (colon) with a flexible tube with a camera. During the exam, biopsies can be taken and most polyps can be removed.

Why it is done

For diagnosis, when there is:

• blood in the stool or iron-deficiency anemia
• chronic diarrhea
• a persistent change in bowel habit
• a positive fecal occult blood test

For screening for colorectal cancer in people without symptoms. The American Cancer Society recommends starting screening at age 45 for people at average risk; the programs of other countries use different thresholds and methods. People with a family history need a separate plan, often starting earlier.

After a normal colonoscopy with good preparation, the next check in people at average risk is usually after 10 years.

Preparation — the most important step

The bowel must be completely clean so that the doctor can see the lining. The unit gives you a written plan for:

• the diet in the days before the exam (usually no fruit or vegetables with seeds and skin, then only clear liquids)
• the laxative preparation, doses and times — often split into two doses, the evening before and the morning of the exam

There is no single scheme for everyone; follow the instructions you receive. The cleansing is sufficient when what comes out is a clear, pale yellow liquid.

Tell the doctor about kidney or heart disease, severe constipation, diabetes, pregnancy and all your medication. Do not stop blood thinners or other medication on your own.

If you vomit or cannot drink the preparation, call the unit — do not add doses on your own.

How it is performed

• Sedation is usually given for comfort.
• The exam takes 20–45 minutes, longer when polyps are removed.
• You may feel mild bloating or cramps from the air introduced into the bowel.
• Removed polyps and biopsies are sent for histological examination.

After the exam

• Bloating and cramps pass within a few hours.
• After sedation: for 24 hours no driving, no machinery and no alcohol. You need someone to accompany you.
• You can usually eat again the same day.

Risks

Colonoscopy is safe. The rare complications are bleeding (especially after polyp removal, sometimes several days later), perforation and reactions to sedation.