From the Guidelines
When a colonoscopy is incomplete due to a tortuous colon and there is suspicion of colon malignancy, the best next step is to perform a CT colonography (virtual colonoscopy). This non-invasive imaging technique uses computed tomography to create detailed images of the colon and can visualize areas that could not be reached during the conventional colonoscopy. According to the American College of Radiology Appropriateness Criteria 1, CT colonography is usually appropriate for colorectal cancer screening after incomplete colonoscopy, regardless of the individual's risk level. The sensitivity and specificity of CT colonography for detecting polyps > 1 cm are 93% and 97%, respectively 1.
Some key points to consider when using CT colonography include:
- It has a staging accuracy of 81% 1
- It is beneficial for evaluating the remainder of the colon after incomplete colonoscopy 1
- It may increase patient willingness to receive regular screening for colorectal cancer 1
- If CT colonography is unavailable or contraindicated, alternative options include double-contrast barium enema or capsule endoscopy 1
- In some cases, a repeat colonoscopy with a pediatric colonoscope or using a different sedation approach might be successful
If a lesion is identified through CT colonography or alternative methods and requires further evaluation, surgical consultation may be necessary for potential segmental resection and pathological examination 1. These alternative approaches are essential because an incomplete colonoscopy leaves portions of the colon unexamined, potentially missing lesions in areas that could not be visualized, which is particularly concerning when there is already suspicion of malignancy.
From the Research
Incomplete Colonoscopy Due to Tortuous Colon
When a colonoscopy is incomplete due to a tortuous colon and there is suspicion of colon malignancy, the next step is crucial for accurate diagnosis and treatment.
- The studies 2, 3, 4, 5 suggest that CT colonoscopy can be a useful adjunct to incomplete colonoscopy, especially in cases where the colonoscopy is incomplete due to a tortuous colon.
- CT colonoscopy has been shown to detect additional lesions, including polyps and cancers, that were missed during the incomplete colonoscopy 2, 4, 5.
- The sensitivity and specificity of CT colonoscopy for detecting colorectal cancer are high, making it a valuable tool for evaluating the entire colorectal segment after an incomplete colonoscopy 4.
- CT colonoscopy can also detect extracolonic findings, such as liver metastases, which can be important for staging and treatment purposes 4, 5.
Comparison with Repeat Colonoscopy
- While repeat colonoscopy with a standard endoscope can be successful in completing the procedure, especially with careful attention to technique 6, CT colonoscopy may be a better option in some cases.
- CT colonoscopy can provide a more comprehensive evaluation of the colon and detect additional lesions that may be missed during a repeat colonoscopy 2, 3, 4, 5.
- However, repeat colonoscopy can also be successful in detecting new adenomas and completing the procedure, especially when using all available endoscopes 6.
Diagnostic Yield of CT Colonoscopy
- The diagnostic yield of CT colonoscopy after incomplete colonoscopy is significant, with studies showing that it can detect relevant additional lesions in 11-27% of patients 2, 5.
- CT colonoscopy can detect both intra- and extracolonic findings, making it a valuable tool for evaluating patients with incomplete colonoscopy 5.