J. Taylor Whaley, MD
Last Modified: June 5, 2016

What is a colonoscopy?

  • A colonoscopy is a procedure that evaluates the lower GI tract. Your GI tract is a long tube and the endoscope (or "scope") can easily pass through it. Using an endoscope, your doctor can assess the health of the rectum, colon, and small intestines.
  • Colonoscopy is used to screen for polyps and precancerous lesions.
  • It is also used for patients who experience rectal bleeding or abnormal bowel movements to identify the causes of these problems.
  • Most colonoscopies occur as outpatient procedures. They are minimally invasive, well tolerated, and widely available.

How do I prepare for a colonoscopy?

  • Preparation for a colonoscopy is very important – if it is not done well and the physician cannot see the bowel lining, the procedure may need to be rescheduled.
  • Every medical practice has a bowel preparation it prefers, thus it is best to follow the instructions you are given.
  • In general, you will need to maintain a clear liquid diet for 1-2 days and take a laxative 24 hours prior to the procedure. This is to ensure that all stool is out of the bowel and that the doctor can see the lining of the intestine clearly.
  • Because sedation will be used, you must fast for 8 hours prior to the procedure.
  • Be sure to discuss any allergies or heart and lung problems you have with the doctor, as this can impact the types of medications that can be used for sedation.
  • If you are on blood thinners, your doctor will likely have you stop them several days in advance. This should be discussed when the biopsy is scheduled.

How is this test performed?

  • A colonoscopy is performed by inserting a camera attached to a long tube through the anus, into the rectum and colon.
  • Prior to the procedure, the patient will be given a sedative (to relax) and possibly a pain medication (to prevent pain). Vital signs are monitored to ensure that the patient's heart rate and blood pressure remain within the normal range. The patient typically will not remember the procedure once it is complete.
  • The patient will lie on a table on his/her side, the sedatives will be given, and then the doctor will insert the scope gently into the anus. The scope has a camera and light attached to the end and can inflate the GI tract with air to help the physician visualize the lining of the tract.
  • The scope has a number of tools, including a needle for biopsy if needed, a cauterizing device to stop bleeding, and a blade if a growth needs to be removed.
  • The actual procedure generally takes 30-60 minutes if no unexpected findings occur. However, because patients must be sedated, woken up, and monitored, the patient may be at the facility for several hours.
  • The most important risk associated with a colonoscopy is an abnormal reaction to sedation. Generally, there is very little bleeding associated with the procedure, although some can occur if a biopsy is taken. There is also a risk of puncturing the GI track, particularly if a biopsy is taken.
  • There can be slight discomfort in the anal area after the procedure, which should resolve over the next few days. If there is severe pain following the procedure, you should contact your doctor immediately.

What to expect after your colonoscopy

  • You will not be able to drive following sedation, so arrangements for a ride home will be needed. Patients should not drive for the remainder of the day.
  • You may experience gas and bloating from the air used to visualize your GI tract.
  • You should return to your normal bowel habits in 2-3 days.
  • A small amount of blood in your first couple of stools after the procedure is normal.

When to Contact Your Provider

  • Severe abdominal pain or if your abdomen becomes bigger and hard to the touch. This can be a side effect of a tear or perforation in your colon and is a medical emergency.
  • Bright red blood in two or more bowel movements or consistent leaking of bright red blood. Nausea and vomiting with blood.
  • Fever greater than 100.4

How do I interpret the results of a colonoscopy report?

  • Following the procedure, the physician will usually discuss their findings with you before you are sent home. It may be helpful to have a friend or family member with you, since you may have some difficulty remembering what is said after sedation.
  • If any biopsies were taken, they will be sent to pathology to determine what was found. It can take 7-10 days for your doctor to receive these results.
  • Your doctor will create a report that is sent to the ordering doctor (often your primary care physician).
    • The first paragraph typically reports the final diagnosis. This is a summary of the findings, often generated to answer the question posed by the ordering physician.
    • It will typically state when the colonoscopy should be repeated. When used for cancer screening, it is usually repeated every 10 years if no concerning lesions were seen (depending upon the patient's health and family history). If polyps or precancerous lesions are seen, it may need to be repeated sooner.
    • The remaining paragraphs generally include the specific technical information that occurred during the procedure. This can include the type of sedation, the details of the findings, biopsies and any complications that occurred.


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