New horizons in the imaging of perianal Crohn's disease: transperineal ultrasonography.

INTRODUCTION: perianal disease, most commonly manifest as fistula or abscess formation, affects up to 40% of patients with crohn's disease. perianal crohn's disease is disabling, associated with poor outcomes, and represents a therapeutic challenge for physicians. correct diagnosis and classification of perianal disease is the first crucial step for appropriate multidisciplinary management. Areas covered: A literature search was performed of the PubMed database using the terms 'transperineal ultrasonography', 'transperineal ultrasound', 'perianal disease', 'perianal fistula', 'perianal abscess', 'magnetic resonance', 'endoanal ultrasonography', 'endoscopic ultrasound' in combination with 'Crohn's disease'. A comprehensive review of the relative advantages and disadvantages of the various methods of evaluation of perianal Crohn's disease is provided. A particular focus is placed on transperineal ultrasonography, including historical and technical factors, advantages and limitations, and its current role in practice. An algorithm for integration of transperineal ultrasound into the management of perianal Crohn's disease into clinical practice is proposed, along with future areas research. Expert commentary: Transperineal ultrasound is a simple, safe, cheap and reliable imaging technique for evaluation of perianal Crohn's disease, which should be used more frequently in clinical practice.