A colonoscopy is a medical examination that identifies abnormalities in the large intestine and rectum.
It involves the use of a long flexible tube (called the colonoscope) which consists of a video camera at the tip. It also has a hollow channel through which small flexible instruments can be passed. This allows the doctor to view the insides of the colon and treat any abnormalities that are detected.
How Is It Performed?
First, the patient is given medication through an intravenous (IV) needle to induce drowsiness and sedation. While the patient is lying on their side, the doctor performs the colonoscopy by inserting a long, flexible tubular instrument into the colon.
This tube consists of a light and video camera at its tip. This camera sends real-time footage to an external monitor so that the doctor can observe the insides for any abnormalities. The instrument is inserted through the rectum and goes all the way to the other end of the large intestine.
The tube can also carry air (or carbon dioxide) which is pumped into the colon to inflate it. This provides a better view of the lining.
The colonoscope transmits an image of the colon and rectum. The doctor is then able to examine the presence of abnormalities (such as growths, polyps, etc.) which can be then removed during the procedure. While removing the instrument, the doctor also examines the lining of the colon. Tiny tissue samples (biopsies) may be removed for testing.
The entire procedure lasts for an average of 30-60 minutes. Patients are advised to relax during this procedure. Mild cramping may be experienced when the tube is moved inside the colon. Slow deep breaths can reduce this cramping significantly.
When Should You Have One
A colonoscopy is a safe procedure that accurately diagnoses and treats abnormalities. A colonoscopy may be performed in the following cases:
- To check for Colon Cancer: A colonoscopy can be scheduled every couple years to screen for colon cancer. The risk of colon cancer increases after the age of 50. Regular checks can prevent the progression of cancer through early detection and appropriate treatment.
- To look for Polyps/Growths: Abnormalities such as polyps are easily detected in a colonoscopy. If a patient has had polyps before, they may require a follow-up colonoscopy to diagnose and treat colonic polyps.
- To look for the causes of Intestinal Symptoms: Some gastrointestinal diseases and disorders may be identified through abnormalities that are visible in a colonoscopy. For instance, the causes of abdominal pain, chronic constipation and diarrhea can be investigated through a colonoscopy.
The frequency of a colonoscopy depends on the individual and their medical history. A doctor may recommend a colonoscopy in 2 years if the person’s medical history records the presence of polyps in previous colonoscopy procedures.
This is because some polyps may be precancerous. Upon examination, if the polyp was found to be cancerous or precancerous, the doctor may recommend a sooner colonoscopy.
The following instances of polyps might require regular colonoscopies:
- Presence of a large polyp (larger than 0.4 inches)
- Presence of multiple polyps
- Presence of precancerous polyps
- Presence of cancerous polyps
A colonoscopy may have to be repeated in 1 year if the doctor was unable to carry out the complete examination of the colon (due to the presence of a polyp or residual stool).
Preparing for a Colonoscopy
Although it is not a major operation, the body must be prepared for a colonoscopy. The most important prerequisite is emptying out the colon.
For this, the doctor may advise a special diet before the day of the colonoscopy. It involves limiting solid food, beverages with milk/cream and red liquids (which can be confused with blood in the exam).
Drinks are thus limited to clear liquids. Further, eating anything after midnight of the night before the exam may be prohibited.
The following can be consumed to prepare for a colonoscopy:
- Strained fruit juice (apple/white grape)
- Sports drinks (lemon/orange)
- Coffee and tea (without milk and cream)
- Fat-free broth
- Gelatin (lemon/orange)
A doctor may also suggest the use of a laxative. A laxative can be taken the night before and the morning of the colonoscopy. This will speed up the process of emptying out any residue in the colon.
If you are on medication at the time of the exam, inform your doctor regarding the types of medications and their purpose. Medicines that thin the blood may need to be adjusted a week before the exam or temporarily stopped. Medications that contain iron must also be specifically reported to the doctor a week before the exam.
What Happens After
Since the procedure involves some amount of sedation/anesthesia, the patient is kept in the recovery room for at least an hour for the effects to wear off. They must also take the rest of the day off, and avoid doing any work/strenuous task. It is normal to feel some cramping and bloating after the exam.
If a polyp was removed during the colonoscopy, additional care might be required. The doctor may suggest that the patient temporarily continues with a special diet until instructed otherwise.
It is normal for patients to notice some rectal bleeding during the first bowel movement after the examination. However, if the bleeding is accompanied by high fever and abdominal pain, the patient must immediately consult their doctor or present to their local emergency department.