A Clinical Trial of Submucosal Saline Injection in Inverted Colonic Diverticula
Colonic diverticulosis is a prevalent colon disorder observed globally, with a notable distinction in its presentation between Asian and Western populations. In Asian patients, diverticulosis is predominantly found in the right colon, whereas Western patients often exhibit left-sided involvement. Among the various manifestations of colonic diverticulosis, inverted colonic diverticula (ICD) are relatively rare, observed in approximately 0.7% of colonoscopy procedures. The clinical significance of ICD lies in its resemblance to colon polyps, which can lead to diagnostic challenges and potential complications such as bowel perforation following biopsy or endoscopic resection. This article explores a clinical trial investigating the use of submucosal saline injection as a diagnostic maneuver to distinguish ICD from colon polyps, thereby reducing the risk of adverse outcomes.
Background and Diagnostic Challenges
Inverted colonic diverticula (ICD) are pseudodiverticula, meaning they do not contain all layers of the bowel wall. This structural characteristic makes them particularly challenging to differentiate from true colon polyps during colonoscopy. Misdiagnosis can lead to unnecessary biopsies or polypectomies, increasing the risk of complications such as perforation. Traditional diagnostic methods for ICD have included double-contrast barium enema and pathologic findings. However, these techniques are not always practical or accessible during routine colonoscopy.
Colonoscopy remains a cornerstone in the diagnosis and management of colonic diverticulosis and its complications. To improve the accuracy of ICD diagnosis, several endoscopic maneuvers have been proposed. These include the radiating pillow sign, which involves repeated probing with forceps to create a central dimple with radiating folds, and the use of air insufflation and water jets to deform or revert the lesion. Additionally, reversion of the ICD with forceps has been employed as a diagnostic technique. However, these methods are not universally reliable, particularly for larger ICDs, and may be limited by technical challenges such as air leakage or difficulty in positioning the forceps.
The Role of Aurora Rings
A more recent development in the diagnosis of ICD is the identification of Aurora rings. These concentric pale rings surrounding the lesion are enhanced with narrow-band imaging and indigo carmine dye. Aurora rings provide a visual cue that can help distinguish ICD from colon polyps without the need for additional maneuvers. However, this sign is not always definitive, especially in cases of smaller ICDs or poor bowel preparation. Furthermore, the effectiveness of Aurora rings is dependent on the use of advanced imaging techniques, which may not be available in all clinical settings.
Submucosal Saline Injection: A Novel Diagnostic Maneuver
The clinical trial described in this article introduces submucosal saline injection as a novel diagnostic maneuver for ICD. This technique leverages the pseudodiverticular nature of ICD, which lacks the full thickness of the bowel wall. When saline is injected into the submucosa surrounding the ICD, only the submucosal layer rises, causing the lesion to flatten or exhibit a central dimple. This response is distinct from that of true polyps, which retain their shape due to the presence of all bowel wall layers.
In the trial, a 69-year-old woman with no significant medical history presented with intermittent abdominal pain in her right lower quadrant. Initial abdominal computed tomography revealed diverticula in the cecum and ascending colon. Colonoscopy identified several diverticula and an 8-mm polypoid lesion in the ascending colon. The surface of the lesion resembled the surrounding normal mucosa, and the Aurora rings sign was ambiguous. Following submucosal saline injection, the lesion flattened with central dimpling, confirming the diagnosis of ICD.
Advantages and Limitations of Submucosal Saline Injection
Submucosal saline injection offers several advantages over traditional diagnostic maneuvers. It is reliable for both small and large ICDs and does not require specialized imaging equipment. The technique is relatively simple to perform and can be integrated into routine colonoscopy procedures. Additionally, when combined with indigo carmine dye, submucosal saline injection can enhance the visualization of Aurora rings, further improving diagnostic accuracy.
However, the technique is not without limitations. A negative finding following submucosal saline injection does not definitively exclude ICD, as the shape and location of the lesion can influence the outcome. Furthermore, the maneuver requires careful execution to avoid complications such as submucosal hematoma or perforation. Despite these challenges, submucosal saline injection represents a promising addition to the diagnostic toolkit for ICD.
Clinical Implications and Recommendations
The findings of this clinical trial have significant implications for the management of colonic diverticulosis. Accurate differentiation of ICD from colon polyps is critical to preventing unnecessary interventions and associated complications. Submucosal saline injection provides a practical and effective method for achieving this distinction, particularly in cases where traditional diagnostic maneuvers are inconclusive.
Endoscopists are encouraged to consider submucosal saline injection as part of their diagnostic approach to ICD, especially when the lesion’s appearance is ambiguous. The use of indigo carmine dye in conjunction with saline injection can further enhance diagnostic accuracy by highlighting Aurora rings. As with any endoscopic technique, proper training and adherence to best practices are essential to ensure patient safety and optimal outcomes.
Conclusion
Inverted colonic diverticula (ICD) pose a diagnostic challenge due to their resemblance to colon polyps. Traditional endoscopic maneuvers, while useful, are not always reliable, particularly for larger lesions. The introduction of submucosal saline injection as a diagnostic tool offers a promising solution to this challenge. By leveraging the pseudodiverticular nature of ICD, this technique provides a simple and effective method for distinguishing ICD from polyps, thereby reducing the risk of complications such as bowel perforation.
The clinical trial described in this article highlights the potential of submucosal saline injection to improve diagnostic accuracy and enhance patient outcomes. As further research and clinical experience accumulate, this technique may become a standard component of the endoscopic evaluation of colonic lesions. For now, endoscopists are encouraged to incorporate submucosal saline injection into their diagnostic repertoire, particularly in cases where the diagnosis of ICD is uncertain.
doi.org/10.1097/CM9.0000000000001485
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