Prospective Comparison of Magnetic Resonance Imaging, Transrectal and Transperineal Sonography, and Surgical Findings in Complicated Perianal Crohn Disease.

ABSTRACT

OBJECTIVES: Magnetic resonance imaging (MRI) and transrectal sonography are the two accepted imaging modalities for evaluation of perianal fistulas and abscesses. Transperineal sonography is a new technique that is easy to learn and can be performed at any time. The purpose of this study was to prospectively compare the diagnostic accuracy of MRI, transrectal sonography, and transperineal sonography with surgical findings in patients with perianal Crohn disease. METHODS: All patients with perianal Crohn disease underwent MRI, transrectal sonography, and transperineal sonography within a few days before surgery. Fistulas were classified as simple (43.8%) or complex (52.2%) based on surgical findings. RESULTS: Twenty-three patients with active perianal Crohn disease (12 women and 11 men; mean age, 29.9 years; current therapy antibiotics, 69.6%; azathioprine, 56.5%; and biologics, 73.9%; previous surgery, 26.1%; and proportion of smokers, 39.1%) were included. Sensitivity values for MRI, transrectal sonography, and transperineal sonography for diagnosis of fistulas were 84.6%, 84.6%, and 100%, respectively. Transperineal sonography was more sensitive for diagnosis of perianal abscesses than MRI and transrectal sonography (100%, 58.8%, and 92.8%). CONCLUSIONS: Transperineal sonography is a very accurate diagnostic method with outstanding sensitivity compared with MRI and transrectal sonography for evaluation of complicated perianal Crohn disease. Due to its simplicity and low cost, it is recommended that transperineal sonography be the first diagnostic modality in these cases.