Like sigmoidoscopy, colonoscopy consists of a visual assessment of the bowels using an endoscope, In colonoscopy, however, the endoscope is advanced deeper into the colon to examine its entire length. This allows for a more thorough examination, but is more invasive. Accordingly, colonoscopy is often indicated as a second step once sigmoidoscopy produces suspicious findings. Colonoscopy allows screening of the colonic mucosa for signs of pathology, such as inflammation, bleeding, tumours, constrictions, scarring, polyps or other abnormalities. It also allows the collection so small tissue samples (biopsy) from any suspicious areas for microscopic analysis. If necessary, small surgical procedures such as removal op polyps or closure of bleeding ulcers can also be carried out by endoscopy. The examination is indicated in patients over the age of 50 years and those with a family history of colorectal cancer or presence of alarm symptoms such as unexplained weight loss or anaemia, or bleeding from the gastrointestinal tract.
What is the preparation for colonoscopy?
Colonoscopy requires a more thorough cleansing of the bowel than sigmoidoscopy. This is achieved by a special diet for a few days before the test, and an enema shortly before the test. In addition, laxatives and large amount of liquid must be taken the day or evening before. Because of the resulting intense diarrhoea, the laxative preparation is considered by many as the most unpleasant part of the procedure. It also requires the patient to stay close to a bathroom. Colonoscopies are usually performed under moderate, so called conscious sedation, or under general anaesthesia. With conscious sedation the patient is drowsy and experiences little or no discomfort, but remains conscious and is able to understand and respond to verbal commands. In contrast, patients receiving general anaesthesia remain completely unconscious during the procedure. Moderate sedation is most commonly used for colonoscopies and is sufficient for a pain-free examination, although this may vary from patient to patient. Full anaesthesia is usually recommended for patients considered at high risk because of age, illness, or a prior history of complications with drugs used for conscious sedation. Some clinics work exclusively with full anaesthesia while other leave the choice to the patient. Do not hesitate to ask questions and clarify any doubts with regard to the anaesthesia prior to the procedure. This will help to reduce anxiety and make the procedure less unpleasant. Remember that you cannot drive after sedation, so ask a family member or friend to pick you up afterwards or book a taxi. You will also need somebody to accompany you home as you will be drowsy with the sedative. Prior to the procedure, you should also talk with your doctor about any medical conditions you have and all prescribed and over-the-counter medicines, vitamins, and supplements you take, including:
- aspirin or medicines that contain aspirin
- nonsteroidal anti-inflammatory drugs such as ibuprofen or naproxen
- arthritis medicines
- blood thinners
- diabetes medicines
- vitamins that contain iron or iron supplements
Your doctor may need to adjust to these medications before the procedure. The preparation is very important step for a successful colonoscopy. It improves accuracy and visibility, and shortens the procedure since debris do not need to be cleaned out. You should therefore follow all instructions and ask questions in case of doubt and report any abnormalities you observe.
How is colonoscopy performed?
When you arrive for your colonoscopy, you will change into a hospital gown that opens at the back. You will then be bought to a private room and lie on your left side on an examination table. You will be given the the anaesthesia through an intravenous line. It has a fast onset of action, meaning you will feel the effects within 1-2 minutes. The doctor will then first examine your anus with a finger and then gently insert the colonoscope, which is about the thickness of a finger. Although your doctor will use lubricating jelly, this might feel uncomfortable. The colonoscope has a light and video camera mounted on its tip so the doctor can see the lining of your colon on a monitor. Your doctor will pump a small amount of air into your bowel to inflate it slightly for a better view. You will be encouraged to pass wind to prevent cramping. The flexible colonoscope will then be advanced slowly through your bowel. Your doctor might ask you to change your position and press slightly on your abdomen to help move the colonoscope in the right direction. Once the tip of the colon or the last portion of the small intestine is reached, the colonoscope is slowly withdrawn while the lining of your bowel is carefully examined. Small tissue samples (biopsy) may be collected and polyps removed. This may be slightly painful. Polyps are usually benign, but in rare cases may change into cancer over time. The removed polyps are therefore sent to a laboratory to verify their benign character. Tissue samples, usually from suspicious areas, are also sent to a laboratory for detailed analysis by microscopy and laboratory testing. This provides additional information on any possible abnormality. Once the lining of the entire colon has been inspected, which takes about 30 minutes, the colonoscope will be carefully removed and you will be brought to a recovery room.
What can I expect after a colonoscopy?
Once the colonoscopy has been completed, you will be monitored for 1 to 2 hours. You may feel a bit tired or sleepy from the sedative. Abdominal cramping or bloating is normal during the first hour after the procedure. You may also pass a small amount of blood from your anus if a biopsy was removed. After the effects of the sedative have passed, you should be ready to go home, but you should be accompanied by a friend or family member. Your doctor will also give you additional instructions on the aftercare. Because of the laxatives used for the cleansing, you may still lose some liquid from your anus and pass gas for up to 24 hours after taking the last dose. The day after the colonoscopy, you should stay on easy-to-digest foods to give your intestines a rest. You should be fully recovered by the next day and be able to go back to a normal diet.
What are the possible side effects of colonoscopy?
Colonoscopy is a relatively save routine diagnostic procedure and complications are rare. However, as with each invasive examination, adverse reactions or complicaitons may occur in a small number of cases. This may be an intollerance to the sedative or pain madication given prior tot he procedure resulting in heart or breathing problems. Since patients are closely monitored during the procedure, any adverse response to such drugs will be noticed and treated imediately by the attendig staff. Other, more delayed, side effects are prolonged bleeding from the site where a tissue sample (biopsy) was collected or a polyp was removed. In very rare cases, the introduction of the colonoscope injure the intestinal wall of the colon, causing perforation, bleeding or infection. The physician performing your colonoscopy will give you a list of symptoms that may indicate such complications along with instructions on what to do if you experience them. In general, yoiu should conctact a doctor imediately in case of:
- severe pain or cramping
- ongoing or severe anal bleeding
- persistent blood in bowel movements
- a hard abdomen
- inability to pass gas or stool
- fever
- dizziness or weakness
How are the results of a colonoscopy interpreted?
Because colonoscopy is a visual examination, the main results are available right after the procedure. The doctor or nurse may discuss them briefly after the sedatives or anaesthesia has worn off. In addition, you may receive an invitation for a more thorough discussion of the results at a later time. This is especially the case if polyps or tissue samples have been removed and are examined in the laboratory, which may take days to weeks. As IBS is not associated with structural changes of the intestinal wall, the results of colonoscopy are negative in patients with true IBS. In contrast, if any changes of the colonic mucosa, such as inflammation, are observed, it may indicate another condition and require additional testing and specific treatment.