Current Techniques in Evaluating Fistula-in-Ano and Perianal Sepsis: Endorectal Ultrasound Technique and Comparison in Accuracy With Surgery and Magnetic Resonance Imaging

Fistula-in-ano and perianal abscess is a very common pathology encountered in a colorectal surgery practice. Surgical therapy is the main form of treatment. The goal is to eliminate the formation of abscess and achieve healing while preserving anal sphincter function. However, recurrence rates are significant, and postoperative stool incontinence can be present. To maximize operative results and minimize recurrence and complications, accurate preoperative assessment of the fistula is necessary. It is now increasingly recognized that preoperative imaging can help identify infection that would have otherwise gone unidentified. Magnetic resonance imaging and endoanal ultrasound findings preoperatively, especially in patients with complex or recurrent fistulas or persistent abscess, have been shown to influence surgery and reduce the change of recurrence. In this article, we will describe the imaging of fistula-in-ano, with an emphasis on magnetic resonance imaging and endoanal ultrasound diagnostic modalities.