Virtual or traditional colonoscopy: what's the difference?
Key takeaways
- Virtual colonoscopy using CT scanning and traditional endoscopic colonoscopy are two techniques for imaging and examining the colon, with complementary indications;
- Both examinations require bowel preparation to clean the colon for optimal visualization;
- Traditional colonoscopy allows for screening, biopsies and polyp removal during the same procedure;
- Virtual colonoscopy does not require sedation, while traditional colonoscopy most often involves light sedation to ensure patient comfort;
- A medical referral is required for these examinations, and fees apply depending on your health insurance plan.
Contents
- What is traditional endoscopic colonoscopy?
- What is virtual colonoscopy using CT scanning?
- Bowel preparation: a step both examinations share
- What to expect during virtual and traditional colonoscopy
- CT vs. endoscopic colonoscopy for detecting polyps
- Colonoscopy for colon cancer screening: what are the risks of each technique?
- Comparison table: virtual vs. traditional colonoscopy
- When should you choose virtual rather than traditional colonoscopy?
- How much does virtual colonoscopy cost compared with traditional colonoscopy?
Introduction
Colorectal cancer is the fourth most commonly diagnosed cancer in Canada. When detected early, it has a cure rate of over 90% and is easier to treat, often with local surgery alone. When found at an advanced stage, it requires more intensive treatments (chemotherapy, radiation therapy, immunotherapy). Imaging-based colon cancer screening relies on two techniques: virtual colonoscopy using CT scanning and traditional endoscopic colonoscopy. The choice of examination depends on your clinical situation, medical history and your treating physician's recommendations.
How do these two methods differ in terms of effectiveness, comfort, preparation and cost?
The team at the Radiologie Dix30 clinic in Brossard, on Montreal's South Shore, explains everything you need to know to better understand the differences between these two approaches.
What is traditional endoscopic colonoscopy?
Traditional colonoscopy is the gold-standard examination for directly viewing the entire colon and rectum. It is performed by a specialist physician using a colonoscope, a flexible tube with a tiny camera and light source at its tip, inserted through the anus.
This examination provides a real-time view of the intestinal lining. It serves both diagnostic and therapeutic purposes. If your doctor identifies an abnormality or a polyp, they can remove it or take a tissue sample directly, without an additional procedure.
What is virtual colonoscopy using CT scanning?
Virtual colonoscopy, also known as CT colonography, is an advanced medical imaging technique that uses CT scanning to produce detailed, three-dimensional images of the inside of the colon.
During this examination, a thin tube is briefly inserted into the rectum to gently introduce carbon dioxide and expand the colon. The scanner then rapidly captures a large number of images. Specialized software creates a virtual reconstruction of the colon, allowing the radiologist to carefully examine the intestinal wall from every angle.
Virtual colonoscopy is a purely diagnostic examination. If the radiologist detects a suspicious lesion or a polyp when reviewing the images, a traditional colonoscopy will need to be scheduled to confirm the diagnosis and provide the necessary treatment.
Bowel preparation: a step both examinations share
Whether you are having a traditional or virtual colonoscopy, thorough bowel preparation is almost always required.
For the doctor or radiologist to see the intestinal wall clearly, the colon must be completely clean.
This preparation generally takes place over two to three days. You will first follow a low-residue diet, then switch to a liquid diet and take laxatives the day before the examination.
Specific instructions, including the type of laxative prescribed, will be provided when you book your appointment.
What to expect during virtual and traditional colonoscopy
Comfort and practical considerations differ considerably between the two examinations, which may influence the patient's choice in consultation with their doctor.
Traditional colonoscopy
Traditional colonoscopy generally takes between 15 and 30 minutes. As the endoscope advances and air is introduced into the folds of the colon, the examination may cause cramping and discomfort. For this reason, light sedation is most often administered intravenously to help the patient relax and minimize pain. After the examination, a period of monitored rest is required, and you must not drive for the rest of the day.
Virtual colonoscopy
Virtual colonoscopy is much faster, with the scanner taking only a few minutes to capture the images. No sedation is required, meaning you remain fully awake and independent from start to finish. You can resume your daily activities and drive immediately after the examination. Discomfort is generally limited to temporary bloating caused by the gas introduced into the colon.
CT vs. endoscopic colonoscopy for detecting polyps
Detecting polyps is central to preventing colorectal cancer. Both examinations can detect these small growths, which may sometimes develop into malignant tumours if left untreated.
Traditional colonoscopy allows polyps to be seen using the camera's magnification. It also allows them to be removed during the same procedure. The tissue removed is then sent to a laboratory for histopathological analysis.
Virtual colonoscopy also has good sensitivity for detecting polyps. However, as mentioned earlier, if a polyp is found, it cannot be removed during a virtual colonoscopy. The patient will then need a traditional colonoscopy to have it removed. Virtual colonoscopy is therefore indicated for patients without symptoms.
Colon cancer screening by colonoscopy: what are the risks of each technique?
Each technique carries its own risks.
Virtual colonoscopy using CT scanning involves low-dose X-rays. Protocols are designed to limit exposure while maintaining optimal image quality for diagnosis.
Traditional colonoscopy does not involve any exposure to X-rays. It does, however, carry the risks inherent in any procedure performed under sedation, as well as a small risk of bleeding or intestinal perforation during polyp removal or manipulation of the endoscope.
Comparison table: virtual vs. traditional colonoscopy
| Caractéristique | Coloscopie virtuelle (CT-scan) | Coloscopie traditionnelle |
|---|---|---|
| Principe | Imagerie 3D par rayons X à faible dose | Exploration endoscopique directe par caméra |
| Préparation intestinale | Requise (généralement sur 3 jours) | Requise (généralement sur 3 jours) |
| Sédation | Aucune sédation nécessaire | Le plus souvent sédation légère par voie veineuse |
| Biopsie et retrait de polypes | Non réalisable | Possible |
| Conduite après l'examen | Autorisée immédiatement | Interdite le reste de la journée (en cas de sédation) |
| En cas d'anomalie | Coloscopie traditionnelle requise | Biopsie et ablation dans le même temps |
When should each technique be considered?
The choice between virtual and traditional colonoscopy is not a matter of personal preference, but depends on a specific medical indication assessed in consultation with your doctor.
Traditional colonoscopy is generally preferred when there are concerning digestive symptoms (bleeding, changes in bowel habits). It is also recommended when there is a high risk of colorectal cancer, such as a family history of colorectal cancer in a first-degree relative (father, mother, brother, sister, child) or inflammatory bowel disease (Crohn's disease, ulcerative colitis).
Virtual colonoscopy may be considered in specific situations, for example when a traditional colonoscopy is incomplete because of an anatomical obstruction, for certain patients with medical contraindications to sedation, or for frail patients who need to avoid the risks of an invasive examination.
Your doctor is the only professional qualified to determine which option best suits your health situation.
How much does virtual colonoscopy cost compared with traditional colonoscopy?
Traditional colonoscopy performed in a public healthcare facility is covered by the RAMQ.
Virtual colonoscopy using CT scanning is not covered by the public health insurance plan. You can contact our team for current pricing. Your private health insurance may cover it in some cases.
To learn more about virtual colonoscopy using CT scanning, visit our page dedicated to this examination.
Radiologie Dix30 in Brossard, on Montreal's South Shore, performs virtual colonoscopies by appointment.
The clinic is open 365 days a year, Monday to Friday from 8 a.m. to 9 p.m. and Saturday to Sunday from 8 a.m. to 8 p.m.
You can send your referral to our team by fax at 450-904-0405 or by email at info@radiologiedix30.com to schedule your examination.
This article is intended strictly for informational purposes and is not a substitute for professional medical advice. If you have any questions about your digestive health, please consult your treating physician to discuss options suited to your age, risk factors and current screening recommendations.
Sources
Colorectal Cancer Canada. Colorectal cancer screening. colorectalcancercanada.com/fr/depistage/depistage-cancer-colorectal
Canadian Cancer Society. Treatment for colon cancer. cancer.ca/fr/cancer-information/cancer-types/colorectal/treatment/colon-cancer
Santé Québec, CISSS de Chaudière-Appalaches. Virtual colonoscopy using computed tomography. cisssca.com/soins-et-services/imagerie-medicale/tomodensitometrie-taco/colonoscopie-virtuelle-en-tomodensitometrie
CISSS de la Côte-Nord. Preparing for a colonoscopy. cisss-cotenord.gouv.qc.ca
