Colonoscopy
What is Colonoscopy?
The colon is the large intestine. It begins where the small intestine ends in the right-lower abdomen, near the appendix inside the right lower abdomen. The colon extends in a wide loop, up the right side of the abdomen to the liver, and across to the left side of the abdomen where it turns down connecting finally to the rectum. It is 5 to 6 feet long. The colon has a number of functions including withdrawing water from the liquid stool that enters it so that a formed stool is produced. Because the colon is full of turns and bends, it is difficult to examine. For this reason, doctors rely on a procedure called a Colonoscopy.
Colonoscopy is the visual examination of the large intestine (colon) using a lighted, Flexible Fiberoptic or Video Endoscope. In this procedure, a doctor directly inspects the inside of the colon, using a long, thin, flexible instrument called a Colonoscope. Colonoscopy is proven to be the best way to completely view the entire colon and diagnose colon and rectum problems. During the procedure, the Colonscope is gently inserted through the rectum up into the colon. The Colonoscope is connected to a video camera and video display monitor so the doctor can closely examine the inside of the colon.
A Colonoscope is much longer than a Sigmoidoscope, so in most cases allows the doctor to see the entire lining of the colon.
Equipment
The flexible Colonoscope is a remarkable piece of equipment that can be directed and moved around the many bends in the colon. These Colonoscopes now come in two types. The original purely fiberoptic instrument has a flexible bundle of glass fibers that collects the lighted image at one end and transfers the image to the eye piece. The newer video endoscopes use a tiny, optically sensitive computer chip at the end. Electronic signals are then transmitted up the scope to a computer which displays the image on a large video screen. An open channel in these scopes allows other instruments to be passed through in order to perform biopsies, remove polyps or inject solutions.
Reasons For The Exam
There are many types of problems that can occur in the colon. The medical history, physical exam, laboratory tests and x-rays can provide information useful in making a diagnosis. Directly viewing the inside of the colon by Colonoscopy is usually the best exam. Colonoscopy is used for:
- Colon cancer -- a serious but highly curable malignancy.
- Polyps -- fleshy tumors which usually are the forerunners of colon cancer.
- Colitis (Ulcerative or Crohn's) -- chronic, recurrent inflammation of the colon.
- Diverticulosis and Diverticulitis -- pockets along the intestinal wall that develop over time and can become infected.
- Bleeding lesions -- bleeding may occur from different points in the colon.
- Abdominal symptoms, such as pain or discomfort, particularly if associated with weight loss or anemia.
- Abnormal barium x-ray exam.
- Chronic diarrhea, constipation, or a change in bowel habits.
- Anemia.
What does the exam involve?
A Colonoscopy usually lasts 15 to 60 minutes and is usually performed on an outpatient basis. You may get an l V (intravenous) line so that medicine can be given through a vein. This medicine will relax you and make you feel sleepy. Your blood pressure, heart rate, and breathing rate will be monitored during and after the test. During the exam, you'll be asked to lie on your side with a drape covering you. Your doctor will insert the Colonoscope through the rectum, move it gently around the bends of the colon and pass it into the bowel, and then draw it out slowly while examining the inside surface. If the doctor sees anything abnormal, such as a sore or a polyp, a biopsy may be done. To do this, a small piece of tissue is taken out through the Colonoscope. Examination of the tissue can help determine if it is a benign (non-cancerous growth, a cancer or a result of inflammation. Polyps, even those that are not cancerous, can cause bleeding and may become cancerous. For this reason, they are usually removed by passing a thin wire snare through the Colonoscope which is used to lasso the polyp to sever it from the wall of the colon. Electrocautery (electrical heat) is applied to painlessly remove it. The polyp is then sent to a lab to be checked under a microscope to see if it has any areas that have changed into cancer.
Other tests can be performed during Colonoscopy, including biopsy to obtain a small tissue specimen for microscopic analysis.
The procedure is seldom remembered by the sedated patient. A recovery area is available to monitor vital signs until the patient is fully awake. It is normal to experience mild cramping or abdominal pressure following the exam. This usually subsides in an hour or so.
What does it feel like?
A Colonoscopy is a relatively safe and pain-free procedure. Because you will be sedated before the exam begins, any feelings of discomfort will be mild. The procedure can sometimes cause slight temporary cramping and you may experience a "gassy" feeling when you are taken to the recovery area. Note: Because you will be given medication for the examination, you should make arrangements to be picked up and driven home.
Preparation for your Colonoscopy
Because a lower GI examination requires looking at the inside of the colon, it must be flushed clean of all waste so that your doctor can have the clearest view possible. A clean colon is important for an accurate examination. Even the smallest amount of waste left in your colon can hide important details and make for an inaccurate exam. If this happens, a repeat exam may be necessary. Specific steps to clean the colon usually begin the day before the exam as prescribed by your physician. Preparation for the test usually includes the following:
(1) Clear liquid diet
You will need to have a clear liquid diet approximately 12-24 hours prior to the Colonoscopy. Drink only clear liquids such as water, ginger-ale, or apple juice. Check with your doctor for your specific instructions.
(2) Bowel evacuents
A bowel evacuent or "prep" will most likely be prescribed. These come in different types based on how they work. Three of the most common preps include: Polyethylene Glycol Solutions (PEGs), sodium phosphate solution, and sodium phosphate tablets.
- PEG: Requires the ingestion of 4 liters (1.04 gallons) of non-absorbable liquid. These come in a variety of flavors which make them more palatable to drink. PEGs work through a "plunger" effect to push out waste matter.
- Sodium phosphate solution: Requires the ingestion of 2 to 3 glasses of salt solution plus additional fluid (as directed by your physician) to keep you well hydrated. This regimen is taken twice, usually the evening before and again the day of the exam. Sodium phosphate solution works by drawing water into the colon and flushing out waste matter.
- Sodium phosphate tablets: Requires the ingestion of a series of virtually tasteless tablets (3 tablets every 15 minutes for 20 tablets) taken the day before and again the day of the procedure. The tablets are taken with a clear fluid (e.g. water; apple juice, clear carbonated soda, etc.). Sodium phosphate tablets also work by drawing water into the colon and flushing out waste matter.
Most patients will state that the prep is the worst part of a Colonoscopy exam but it is very important. Each preparation will be tolerated differently so talk to your physician for the best option for you.
Who should have a Colonoscopy?
If you have a change in your bowel habits or bleeding, indicating a possible problem in the colon or rectum, your physician may recommend a Colonoscopy. A Colonoscopy is also recommended to:
- Check unexplained abdominal symptoms Check for inflammatory bowel disease (colitis).
- Verify findings of polyps or tumors located with a barium enema exam or after Sigmoidoscopy.
- Examine patients who test positive for blood in the stool.
- Monitor patients with a past history of colon polyps or cancer.
- Finally, if you are at least 50 years old, you should talk to your doctor regarding a colon cancer screening program that is appropriate for you.
Results
After the exam, the physician explains the findings to the patient and family. If the effects of the sedatives are prolonged, the physician may suggest an appointment at a later date. If a biopsy has been performed or a polyp removed, the results of these are not available for three to seven days.
What are the benefits of Colonoscopy?
A Colonoscopy is performed to identify and/or correct a problem in the colon. Colonoscopy has been recently shown to be more accurate at detecting polyps and colon cancer than other forms of colon diagnostic procedures such as barium enema and Sigmoidoscopy. It allows your physician to thoroughly examine the entire colon, viewing the most distal portion.
Physicians also use it to perform biopsies and remove colon polyps eliminating the need for a major operation later. Removal of polyps has been shown to be a major factor in decreasing the incidence of colon cancer. With Colonoscopy, it is possible to simultaneously detect and remove most polyps without abdominal surgery. If a bleeding site is identified, treatment can be administered to stop the bleeding. Other treatments can be given through the Endoscope when necessary. Most Colonoscopies are done on an outpatient basis with minimal inconvenience and discomfort.
Alternative Testing
Alternative tests to Colonoscopy include a barium enema or other types of x-ray exams that outline the colon and allow a diagnosis to be made. Study of the stools and blood can provide indirect information about a colon condition. These exams, however, do not allow direct viewing of the colon, removal of polyps, or the completion of biopsies.
Side Effects and Risks
Bloating and distension typically occur for about an hour after the exam until the air is expelled. Serious risks with Colonoscopy, however, are very uncommon. One such risk is excessive bleeding, especially with the removal of a large polyp. In rare instances, a tear in the lining of the colon can occur. These complications may require hospitalization and, rarely, surgery. Quite uncommonly a diagnostic error or oversight may occur. Due to the mild sedation, the patient should not drive or operate machinery following the exam. For this reason, someone should be available to drive the patient home.
Summary
Colonoscopy is an outpatient exam that is performed with the patient lightly sedated. The procedure provides significant information used to determine which specific treatment will be given. In certain cases, therapy can be administered directly through the Endoscope. Serious complications rarely occur from Colonoscopy.