Transperineal ultrasound for assessment of fistulas and abscesses: a pictorial essay.

Perianal fistulas and abscesses may be cryptogenetic or associated with inflammatory bowel disease (IBD), specifically Crohn's disease. Proper identification and classification of these lesions are paramount for correct therapeutic management. Current diagnostic modalities include MRI (magnetic resonance imaging), EUS (endoscopic ultrasound), EUA (exam under anaesthesia) and recently, transperineal ultrasound (TPUS). The latter has been proposed as a noninvasive, easily available and cost-effective technique to diagnose, assess and follow up perianal disease particularly in IBD patients. This pictorial review focuses on the role of TPUS in clinical practice, highlighting the features of fistulas and abscesses.