From the Guidelines
CT colonography is the preferred alternative to colonoscopy when the latter is not feasible, due to its higher sensitivity and specificity in detecting colorectal lesions, as shown in a study published in 2018 1. When considering alternatives to colonoscopy, several options are available, including Air Contrast Barium Enema (ACBE), CT colonography, and flexible sigmoidoscopy.
- ACBE involves filling the colon with barium sulfate and air to create detailed X-ray images of the large intestine, and is less invasive than colonoscopy, but may cause mild discomfort from the distension of the colon.
- CT colonography, on the other hand, is a non-invasive procedure that uses computed tomography (CT) scans to produce detailed images of the colon and rectum, and has been shown to be highly sensitive and specific in detecting colorectal lesions, especially in patients who have undergone incomplete colonoscopy 1.
- Flexible sigmoidoscopy is another alternative, which involves using a flexible tube with a camera and light on the end to examine the lower part of the colon, but it is limited in its ability to detect lesions in the upper part of the colon. The choice of alternative procedure depends on the specific clinical situation, patient preferences, and the availability of resources.
- For example, CT colonography may be preferred in patients who are at high risk of colorectal cancer or who have undergone incomplete colonoscopy, due to its high sensitivity and specificity in detecting colorectal lesions 1.
- In contrast, ACBE may be preferred in patients who are unable to undergo CT colonography or who have certain medical conditions that make CT colonography contraindicated. It's also worth noting that CT colonography has few contraindications, but should not be performed in patients in whom perforation is a risk, and should probably not be performed immediately after failed colonoscopy in patients who had polyps removed or large biopsy specimens taken during colonoscopy, due to the risk of perforation from colonic insufflation 1. Overall, the choice of alternative procedure to colonoscopy should be made on a case-by-case basis, taking into account the individual patient's needs and circumstances, and CT colonography is generally the preferred alternative due to its high sensitivity and specificity in detecting colorectal lesions.
From the Research
Alternative to Colonoscopy
When colonoscopy is not feasible, an Air Contrast Barium Enema (ACBE) can be considered as an alternative diagnostic tool.
- ACBE is less expensive and invasive than colonoscopy, but it is also less sensitive and specific 2
- ACBE may be less painful than colonoscopy, but it is often poorly tolerated by patients 2
- ACBE can accurately detect colon cancer and diverticula, but its sensitivity for detection of polypoid lesions or adenomas is poor 2
Comparison with Colonoscopy
- Colonoscopy has the advantage of detecting a larger number of lesions and smaller lesions, and the ability to be therapeutic as well as diagnostic 3
- Colonoscopy can guide the surgeon in doing proper resections, based on tissue diagnoses, in cases when there are several lesions in different locations in the colon 3
- If colonoscopy cannot be performed, or cannot be completed to the cecum, then the next best choice is to proceed to double contrast barium enema 3
Factors Affecting Technical Difficulty
- Advanced age, female gender, low BMI, poor bowel preparation, and patient pain are independent factors related to prolonged cecal intubation time, making colonoscopy more difficult 4
- In patients with these factors, information that colonoscopy may be difficult and painful should be provided, and alternative diagnostic modalities such as barium enema or CT colonography may be considered 4
Diagnostic Strategies
- The choice of diagnostic strategy depends on various factors, including demographic factors such as age and sex, which are better predictors of the presence of adenomas than symptoms 5
- Cost-effective selection of imaging strategies can be based on these factors, and initial colonoscopy may be more cost-effective for the outcomes of detection of adenomas and detection of large adenomas 5