Colonoscopy Test and Procedure
Overview
A colonoscopy is a common procedure in gastroenterology that helps doctors check the colon and rectum for unusual changes, such as swelling, irritated areas, polyps, or early signs of cancer.
This exam uses a flexible tube called a colonoscope, which has a small camera on the tip. The doctor gently inserts the tube into the rectum and views the inside of the large intestine.
Key Features:
- Examines: Colon and rectum.
- Tool: Colonoscope equipped with a video camera.
- Treatment: Doctors can remove polyps or abnormal tissue.
- Digestive health: Doctors often take biopsies to help with diagnosis.
Reasons for the Procedure
Doctors often perform a colonoscopy to investigate symptoms such as ongoing abdominal pain, rectal bleeding, or chronic diarrhea. It helps identify the cause of these issues by allowing direct examination of the colon.
Colonoscopy is also a key screening tool for colorectal cancer, especially in adults aged 45 and older. It is one of the most effective methods for detecting cancer early, when treatment is more likely to succeed.
Another important reason for the procedure is to detect and remove polyps—small growths in the colon that may develop into cancer over time. Removing them during the exam helps lower the risk of future colorectal cancer.
In addition to diagnosis and prevention, colonoscopy can be used to treat certain conditions. These include removing foreign objects, stopping intestinal bleeding, or placing a stent to relieve a blockage.
While colonoscopy is a leading option for screening, other tests are available. These include the fecal immunochemical test (FIT), virtual colonoscopy (CT colonography), and other imaging methods.
Additional Details
Colonoscopy can help uncover a range of other health problems, including:
| Condition | Description |
|---|---|
| Colon polyps | Growths that may turn cancerous. |
| Inflammatory bowel disease | Ongoing inflammation in the digestive tract. |
| Iron deficiency anemia | Low red blood cell count from bleeding. |
| Ulcerative colitis | Inflammation and sores in the colon. |
| Crohn’s disease | Ongoing inflammation in the intestines. |
| Constipation | Difficulty passing stool. |
| Proctitis | Swelling in the lining of the rectum. |
| Carcinoid tumors | Rare slow-growing tumors. |
| Intestinal ischemia | Reduced blood flow to the intestines. |
Anyone with ongoing symptoms like anal itching, unexplained anemia, or changes in bowel habits may need further evaluation by colonoscopy.
Possible Complications
Some people may have side effects after a colonoscopy, but most risks are uncommon.
Possible complications include:
- Reaction to Sedatives: Some people may have problems from the medicine used to help them relax.
- Bleeding: Bleeding can occur at spots where the doctor removes tissue or polyps.
- Tear in the Colon: Rarely, a small rip can occur in the colon or rectum wall (perforation).
Doctors usually explain these issues and do a risk assessment before the test.
How You Prepare
Preparing for a colonoscopy involves several important steps to make sure the colon is clean so the doctor can get clear images.
| Step | Details |
|---|---|
| Diet | Clear liquids only and avoid red liquids. |
| Bowel Prep | Use a laxative or preparation kit as directed. |
| Medications | Review with doctor and make adjustments. |
| Day of Exam | No eating/drinking after midnight. |
| During Exam | Provider gives a sedative or anesthesia. |
The process begins by changing the diet. Most people are instructed to stop eating solid foods the day before the test. Only clear liquids—such as plain water, tea or coffee without milk, clear broth, or soda—are usually allowed.
Red-colored drinks should be avoided, as the color can resemble blood during the exam. In many cases, all food and drink must be stopped after midnight.
A key part of preparation involves taking a bowel prep, or laxative, to empty the colon. The doctor typically prescribes a specific medication, which may come in pill or liquid form. The timing of the dose depends on the doctor’s instructions.
Some people take it all the night before the test, while others split the dose between the night before and the morning of the procedure. This step causes frequent bowel movements to help fully clear the colon.
While enemas are rarely needed, a doctor may recommend one in addition to the bowel prep if extra clearing is required.
Before the procedure, it’s important to discuss all current medications with the doctor—especially for those with diabetes, high blood pressure, heart problems, or those taking blood-thinning medications. Some drugs may need to be stopped or adjusted for a few days, so always check with the provider beforehand.
What You Can Expect
During the Test
Staff usually ask patients to change into a gown and set aside other clothing. The provider administers sedation for the patient’s comfort, typically delivering it intravenously. This helps with pain and keeps the person relaxed.
The gastroenterologist will ask the patient to lie on their side, with knees close to the chest. The doctor gently guides a colonoscope, which is a thin, flexible tube with a small video camera and light at the tip, into the rectum.
The device is long enough to reach all the way through the large intestine, up to the cecum. To make the inner lining easier to see, the provider sends air or carbon dioxide through the colonoscope.
This inflation can cause bloating or mild cramping. Some people feel an urge to use the bathroom during this part. The camera sends live images to a monitor so the doctor can look for any unusual areas.
If the gastroenterologist sees polyps or abnormal tissue, they can pass small tools through the colonoscope to take samples (biopsies) or to remove polyps. The whole process usually takes between 30 and 60 minutes.
Key Parts of the Examination
| Step | What happens |
|---|---|
| Sedation | The healthcare provider administers intravenous medication to ensure the patient’s comfort. |
| Scope insertion | The doctor carefully inserts a slender tube through the rectum. |
| Colon inflation | Air or gas opens up the large intestine. |
| Video monitoring | Live camera feed to external screen. |
| Polyp removal/Biopsy | The doctor will remove tissue if necessary. |
After the Test
After the colonoscopy, most people spend about an hour in a recovery area while the sedation wears off. Because the effects of sedation can linger for the rest of the day, patients will need someone to drive them home. It’s not safe to drive, return to work, or make important decisions right away.
During recovery, it’s normal to feel gassy or bloated as the body releases leftover air from the colon. Light walking may help ease this discomfort. You might also notice a small amount of blood during your first bowel movement. In most cases, this is not serious.
Most people recover quickly and feel back to normal by the next day. If any polyps were removed or biopsies taken, the gastroenterologist will explain the findings and follow up with results.
Test Findings
No Abnormalities Found
If the colonoscopy shows no unusual findings in the large intestine, it is considered a normal result. Patients at average risk of colon cancer, with no family history or significant risk factors, usually need a follow-up colonoscopy in 10 years.
| Risk Level/Findings | Follow-Up Interval |
|---|---|
| Average risk & no polyps | Every 10 years |
| History of polyps/family risk | Every 1–7 years |
However, people with a family history of colon cancer, inherited conditions, or a history of multiple polyps may need more frequent exams, usually every 1 to 7 years.
Growths or Unusual Tissue Found
If the doctor finds growths called polyps or other unusual areas, the colonoscopy is considered to have abnormal results. Most polyps are noncancerous, but some can develop into cancer over time. Any removed polyps or biopsy samples are sent to a lab for evaluation.
Follow-up depends on the number, size, and type of polyps:
- One to Two Small Polyps: Repeat in 7–10 years.
- More Than Two Polyps: More frequent exams.
- Large Polyps: Sooner follow-up.
- Polyps Were Not All Removed: Another specialist or surgeon may be needed.
If the doctor discovers signs of inflammatory bowel disease (IBD), ulcerative colitis, or diverticula, closer monitoring or different treatment plans may be discussed. If cancer is detected, patients are referred for further evaluation and treatment, such as surgery, medications, or other therapies.
Issues During Your Procedure
In some cases, the exam may not be completed as planned. This can happen if:
- The bowel wasn’t fully clean, making it difficult to view certain areas.
- The scope cannot pass through the entire colon.
- There is unusual anatomy, such as diverticula or inflammation from conditions like inflammatory bowel disease (IBD).
If visibility is limited, the doctor may recommend a repeat colonoscopy sooner. Proper bowel prep before the next procedure helps ensure a more complete and accurate exam.
When full access isn’t possible, the provider might also suggest a different imaging test, such as a CT colonography (virtual colonoscopy), to examine areas that were missed.
Doctors will adjust your care plan based on what was found and may suggest steps to improve the success of future exams. Tools like checklists or reminder charts can help patients stay on track for their next procedure and instructions.
