Understanding Colonoscopies
- kristina8391
- Mar 17
- 6 min read
Dr. Donald Greig
What is a Colonoscopy?
A colonoscopy is a medical procedure that allows a doctor to examine the inside of your colon (large intestine / bowel) using a long, flexible tube known as a colonoscope. This tool is equipped with a light and camera, enabling the doctor to visualize the lining of the colon and rectum in detail. While colorectal cancer prevention and early detection are the prime reasons for performing a colonoscopy, the procedure is used to diagnose many other bowel conditions such as inflammatory bowel disease (ulcerative colitis to Crohn’s disease, diverticular disease and vascular malformations which can cause rectal bleeding.
Why is a Colonoscopy Needed?
Colonoscopy is a critical tool for diagnosing and preventing colorectal issues. Colorectal cancer is a serious health concern around the world. According to the World Health Organization (WHO), colon cancer is the second leading cause of cancer-related deaths worldwide. In 2020, more than 1.9 million new cases of colorectal cancer and more than 930,000 deaths due to colorectal cancer were estimated to have occurred worldwide. Large geographical variations in incidence and mortality rates were observed. The incidence rates were highest in Europe, Australia, New Zealand, Central and South America, and the mortality rates were highest in Eastern Europe. The lowest rates are seen in parts of Africa and South-Central Asia. By 2040, the burden of colorectal cancer will increase to 3.2 million new cases per year (an increase of 63%) and 1.6 million deaths per year (an increase of 73%).
Colorectal cancer is the third commonest cancer in Hong Kong. It accounted for 14.7% of all new cancer cases in 2022. There were 5,190 new cases of colorectal cancer in 2022, with 2,928 male cases and 2,262 female cases. The male to female ratio of incidence was about 1.3 to 1.
Here are some key reasons it might be recommended:
Screening for Colorectal Cancer: It is the gold standard for screening, especially for individuals aged 40 and older, or those with risk factors as screening can catch prevent cancer by removing precancerous polyps, detect cancer at an earlier, more treatable stage.
Investigating Symptoms: If you experience symptoms such as unexplained abdominal pain, rectal bleeding, or significant changes in bowel habit, a colonoscopy can help identify the underlying issues, which may include inflammatory bowel disease (IBD), diverticulitis, or polyps.
Removing Polyps: A colonoscopy allows for the removal of polyps, which are usually benign abnormal growths that can develop on the bowel lining. Polyps are extremely common, present in up to 95% of patients examined. However, 27% of patients will have precancerous, yet benign polyps which, if removed, stop colorectal cancer from forming. The U.S. Preventive Services Task Force recommends regular screenings to remove these polyps before they can progress to cancer.
Monitoring Conditions: Such as inflammatory bowel disease (IBD) or previous colon cancer or precancerous polyp removal.
How is a Colonoscopy Performed?
Preparation: Preparation is crucial for a successful colonoscopy as polyps down to the size of 0.5mm can be detected and then removed. Patients are advised to follow specific dietary restrictions (2 days before) and take bowel preparation laxatives the day before to clear the bowel completely.
Anaesthesia: so that patients are comfortable during the procedure, it is my practice to use Monitored Anaesthesia Care (MAC) with propofol, administered by an anaesthetist, a short-acting intravenous anaesthetic that allows for a more rapid recovery. The patient is unconscious but it is not general anaesthesia. Similarly, patients are not conscious yet sedated as this employs Valium type drugs, which are less safe and much longer lasting post procedure than the propofol.
Procedure:
The patient lies on their side, typically in a comfortable position.
Once the patient has been given the propofol and is lightly anaesthetised….
The doctor gently inserts the colonoscope through the rectum and advances it into the colon.
The camera transmits real-time images to a monitor, allowing for detailed examination of the colon lining.
If polyps or other abnormalities are detected, they are removed or biopsied during the procedure.
The procedure usually takes about 30 to 60 minutes.
Benefits of a Colonoscopy
Early Detection: Identifying and removing precancerous polyps can prevent the risk of developing colorectal cancer.
Comprehensive Examination: The procedure allows for a thorough examination of the colon and rectum.
Polyp Removal: If polyps are found, they can often be removed during the procedure, reducing future cancer risk by cold or hot snare, or repeated use of biopsy forceps passed down a dedicated channel in the colonoscope.
Minimal Discomfort: Thanks to propofol, modern techniques, use of CO2 rather than air to insufflate the bowel to see the way ahead, most patients report minimal discomfort and are usually discharged the same day.
Potential Complications
While colonoscopy is generally safe and the benefits substantive, some potential risks include:
Bleeding: This can occur, particularly if polyps on a stalk are removed, but is rare especially with the more routine use of metal clips to seal the base of elongated polyps or close any defects in lining of the bowel.
Perforation: Rarely, the colon may be punctured, which may require surgical intervention. The incidence is quoted as 1 in 500-1000. However, it is directly related to the experience of the colonoscopist.
Reactions to Sedation: Some patients may experience adverse effects from the anaesthesia, so it’s essential that all patients are assessed by the colonoscopist and the anaesthetist prior to the procedure.
Retained gas and colicky abdominal pain: post procedure has virtually been eliminated now with the routine use of CO2 to insufflate the bowel.
Where is a Colonoscopy Performed?
Colonoscopy is typically performed in:
Hospitals: my preference is to admit all patients to hospital as it provides a comprehensively safer environment where the rare unexpected events which may occur, can be dealt with more effectively than in setting where there are less personnel, drugs and equipment available.
Specialized Clinics: However, it is recognized that some gastroenterology practices have dedicated well-resourced facilities for outpatient colonoscopies.
Imaging Techniques
During a colonoscopy, various imaging techniques can enhance the examination:
White Light Imaging: This is the standard technique for visualizing the colon lining and can detect most abnormalities.
Narrow Band Imaging (NBI): This advanced technique uses specific wavelengths of light to enhance the visualization of blood vessels and mucosal patterns, mproving the detection rate of polyps and other abnormalities.
 |  |
Precancerous tubular adenomatous polyp seen with white light and NBI
Recovery:
The recovery time after a colonoscopy with propofol sedation is generally quick. Here’s what you can expect:
Immediate Recovery: After the procedure, you'll be monitored for about 30 minutes to an hour in a recovery area. During this time, the effects of the propofol will wear off.
Return to Normal Activities: Most patients feel alert and can resume normal activities within a few hours. However, it’s recommended to have someone drive you home, as you may still feel groggy.
Post-Procedure Discomfort: Some patients may experience mild abdominal bloating or discomfort but this is usually not a feature of CO2 insufflation. This typically resolves within a few hours.
Dietary Considerations: You can usually resume a normal diet shortly after the procedure, but it’s advisable to start with light foods and gradually return to your regular diet.
Monitoring for Complications: While serious complications are rare, it's important to monitor for any unusual symptoms, such as severe abdominal pain, persistent bleeding, or fever, and to contact your healthcare provider if these occur.
Prescription medications: your doctor will advise when they can be resumed, but generally, straight away.
In summary, most patients can expect to feel back to normal within a few hours after a colonoscopy with propofol sedation, though full recovery may take the rest of the day.
Conclusion
A colonoscopy is a crucial procedure for maintaining colorectal health. By understanding the need for this examination, how it is performed, its benefits, and potential risks of this procedure empowers you to make informed health decisions.
If you have further questions or would like to schedule a colonoscopy, please contact our office at The New Clinic.
Stay Healthy, Stay Informed!
For more information, feel free to reach out or visit our website.
Disclaimer: This newsletter is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider for any medical concerns.
Comments