What is a colonoscopy?

Colonoscopy lets your doctor examine the lining of your large intestine (colon) for abnormalities by inserting a thin flexible tube, as thick as your finger, into your anus and slowly advancing it into the rectum and colon. This instrument, called a colonoscope, has its own lens and light source and it allows your doctor to view images on a video monitor.

What happens during colonoscopy?  

Colonoscopy is well-tolerated and rarely causes much pain. You might feel pressure, bloating or cramping during the procedure. Typically, your doctor will give you a sedative to help you relax and better tolerate any discomfort. You will lie on your side or back while your doctor slowly advances a colonoscope along your large intestine to examine the lining. Your doctor will examine the lining again as he or she slowly withdraws the colonoscope. The procedure itself usually takes less than 45 minutes, although you should plan on two to three hours for waiting, preparation and recovery. In some cases, the doctor cannot pass the colonoscope through the entire colon to where it meets the small intestine. Your doctor will advise you whether any additional testing is necessary.

What preparations are required?

Your doctor will tell you what dietary restrictions to follow and what cleansing routine to use. In general, the preparation consists of limiting your diet to clear liquids the
day before and consuming either a large volume of a special cleansing solution or special oral laxatives. The colon must be completely clean for the procedure to be accurate and comprehensive, so be sure to follow your doctor’s instructions carefully.


From the American Gastroenterological Association
References: ASGE, American Society for Gastrointestinal Endoscopy

Colonoscopy: What You Need To Know