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Colonoscopy is a medical procedure used to examine the inside of the colon and rectum using a long, flexible tube with a camera on the end called a colonoscope.

This test is typically performed to investigate possible causes of abdominal pain, rectal bleeding, or changes in bowel habits, or to screen for colon cancer or polyps.

During a colonoscopy, the patient is sedated and the colonoscope is gently inserted through the rectum and advanced up through the colon while the doctor examines the images on a monitor.

If any abnormalities are detected, the doctor may take a biopsy or remove a polyp for further examination.

Colonoscopy is a safe and effective way to diagnose and prevent colon cancer and is recommended for most individuals over the age of 50, or earlier for those at higher risk.


Preparation for a Colonoscopy

Preparing for a colonoscopy is a crucial step in ensuring accurate results and a successful procedure.

Your doctor will provide you with specific instructions for preparing for the colonoscopy, which may include a clear liquid diet the day before the procedure, and the use of laxatives or enemas to empty the colon.

It is important to follow these instructions carefully to ensure the best possible results.

In some cases, your doctor may also advise you to stop taking certain medications in the days leading up to the colonoscopy, so be sure to discuss your current medications with your doctor.

colonoscopy procedure - Colonoscopy: Why It's Important for Detecting Colon Cancer and What to Expect


Why You Might Need a Colonoscopy


A colonoscopy is a diagnostic procedure that allows a gastroenterologist to examine the inner lining of the large intestine (colon) using a flexible tube with a camera at the end.

Here are some reasons why you might need a colonoscopy:

  • Screening for colon cancer: Colonoscopy is the gold standard for colon cancer screening, especially for individuals over the age of 50 or those with a family history of colon cancer. 
  • Abdominal pain and rectal bleeding: These symptoms can indicate the presence of colon polyps, inflammation, or other abnormalities. 
  • Chronic diarrhea or constipation: These symptoms can be caused by conditions such as inflammatory bowel disease (IBD), diverticulitis, or colorectal cancer. 
  • Change in bowel habits: Changes in bowel habits, such as increased frequency or changes in stool consistency, may indicate a problem in the colon. 
  • Anemia: Unexplained anemia may be a sign of bleeding in the colon.

If you are experiencing any of these symptoms, or if you have a family history of colon cancer or other colon disorders, it’s important to talk to your healthcare provider about whether a colonoscopy is necessary.

colonoscopy detecting colon cancer - Colonoscopy: Why It's Important for Detecting Colon Cancer and What to Expect

Importance of Colonoscopies for Detecting Colon Cancer

Colonoscopies are essential for detecting colon cancer, which is one of the most common types of cancer in the world.

Colon cancer often has no symptoms in its early stages, which makes it difficult to diagnose without screening tests like colonoscopies.

However, if colon cancer is caught early, it is often treatable and has a high survival rate.

This is why regular colonoscopies are so important, especially for people over 50 or those with a family history of colon cancer.

By detecting and removing precancerous polyps during a colonoscopy, the risk of developing colon cancer can be greatly reduced.


What Is a Colon Polyp?

A colon polyp is a growth that develops on the inner lining of the large intestine (colon) or rectum.

Most polyps are benign (non-cancerous), but some types can develop into colon cancer over time if left untreated. Colon polyps are very common, especially in people over the age of 50.

There are different types of colon polyps, but the two most common types are:

  • Adenomatous polyps: These polyps are more likely to turn into cancer over time, so they are typically removed during a colonoscopy.
  • Hyperplastic polyps: These polyps are less likely to become cancerous, so they may not require removal unless they are large or cause symptoms.

Most people with colon polyps don’t experience any symptoms, which is why regular screenings such as colonoscopies are important for detecting and removing polyps before they have a chance to turn into cancer.

Some possible symptoms of colon polyps may include:

  • Blood in the stool
  • Rectal bleeding
  • Changes in bowel habits, such as diarrhea or constipation
  • Abdominal pain or discomfort
  • Fatigue or weakness (if the polyps cause bleeding)

If you experience any of these symptoms, or if you’re due for a routine colon cancer screening, talk to your healthcare provider about scheduling a colonoscopy.

what happens during a colonoscopy - Colonoscopy: Why It's Important for Detecting Colon Cancer and What to Expect


During the Colonoscopy

During a colonoscopy, a gastroenterologist uses a flexible, tube-like instrument called a colonoscope to examine the lining of the large intestine (colon) and rectum.

The colonoscope is inserted through the anus and gradually advanced through the colon while the patient is sedated.

The doctor can view the colon lining on a video monitor attached to the colonoscope and can take biopsies or remove any abnormal growths (polyps) for further examination.

The procedure typically takes about 30-60 minutes and is considered safe and effective for early detection of colon cancer.


After the Colonoscopy

After a colonoscopy, the patient is taken to a recovery area where they are monitored until the sedative wears off.

Patients are advised not to drive, operate heavy machinery, or make important decisions for at least 24 hours after the procedure.

Mild side effects like bloating and cramping may occur and should go away on their own within a few hours. In rare cases, complications such as bleeding, infection, or bowel perforation may occur.

Patients should contact their doctor immediately if they experience severe abdominal pain, rectal bleeding, fever, or other unusual symptoms.

The doctor will discuss the findings of the colonoscopy with the patient and recommend any necessary follow-up care.

If no polyps or abnormalities are found, the patient may be advised to have another colonoscopy in 10 years, although this may vary depending on individual risk factors.


Risks of a Colonoscopy


Like any medical procedure, colonoscopy does carry some risks.

However, the benefits of colonoscopy in detecting and preventing colon cancer far outweigh the risks for most people.

Here are some potential risks of colonoscopy:

  • Bleeding: During the procedure, the gastroenterologist may remove polyps or take biopsies, which can cause bleeding. In most cases, the bleeding is minor and stops on its own, but in rare cases, additional medical treatment may be required. 
  • Perforation: In rare cases, the colonoscope can puncture the wall of the colon, leading to a perforation. This can cause abdominal pain, fever, and infection, and may require surgery to repair. 
  • Reaction to sedation: The medications used for sedation during a colonoscopy can cause allergic reactions or breathing difficulties in rare cases. 
  • Incomplete exam: In some cases, the gastroenterologist may not be able to complete the exam due to technical difficulties, patient discomfort, or other factors. 

It’s important to note that the risks of colonoscopy are generally very low, and most people experience no complications.

Your gastroenterologist will discuss any potential risks with you before the procedure and will take steps to minimize the risks, such as using the lowest possible doses of sedation and monitoring you closely during the procedure.

If you have any concerns about the risks of colonoscopy, talk to your healthcare provider.



Colonoscopy is a critical tool for preventing colon cancer by detecting and removing polyps before they turn cancerous.

If you’re over the age of 50, or have a family history of colon cancer or other colon disorders, talk to your healthcare provider about scheduling a colonoscopy.

With early detection and treatment, colon cancer is highly treatable, and regular colonoscopy screenings can help save lives.

By making lifestyle changes and following a treatment plan, you can improve liver function and reduce the risk of complications associated with fatty liver disease.

If you think you might have fatty liver disease, talk to your doctor about how to get a diagnosis.

Dr. Schneider is located at the Millpark Hospital, Parktown, Johannesburg.

Services offered include consultation, and endoscopy procedures, including gastroscopy, colonoscopy and video capsule endoscopy.

For more information on the diagnosis and treatment of abdominal pain in Johannesburg, contact Dr. Schneider or book your consultation today.



The information on this website is to provide general guidance. In no way does any of the information provided reflect definitive medical advice and self-diagnoses should not be made based on information obtained online. It is important to consult a Gastroenterologist or medical doctor regarding ANY and ALL symptoms or signs including, but not limited to: abdominal pain, haemorrhoids or anal / rectal bleeding as it may a sign of a serious illness or condition. A thorough consultation and examination should ALWAYS be performed for an accurate diagnosis and treatment plan. Be sure to call a physician or call our office today and schedule a consultation.