Perianal Crohn's: Review of endoscopic and cross-sectional imaging

Crohn's disease has many manifestations and can affect any aspect of the gastrointestinal lumen. In this article, we would review perianal manifestations of Crohn's disease, which includes the formation of fistula tracts, strictures, and abscesses. Perirectal fistulas can be particularly challenging to manage because of the complexity in diagnosis. Additionally, clinical symptoms of perirectal disease do not always reflect disease activity. Perianal fistulas are important to diagnose early and accurately because of associated complication of abscess formation.We would review diagnostic tools to evaluate perirectal disease. These would include examination under anesthesia, fistulography, and computerized tomography imaging. Endoscopic ultrasound and magnetic resonance imaging are particularly useful in the classification of perirectal disease and are used to monitor disease activity as well as response to medication or surgical therapy or both. The uses and the limitations of these studies would be reviewed in this article. We would also review the technique of endoscopic ultrasound, its uses, along with its limitations. The classification of fistulas as simple and complex with endoscopic ultrasound helps determine treatment course from antibiotics to biologic agents to surgical therapy for more complex disease.