Endosonography in anorectal disease: an overview

Area of Science:

• Gastroenterology and Colorectal Surgery
• Medical Imaging and Diagnostics

Background:

• Anorectal endosonography (AE), derived from urology, has been used for two decades to evaluate rectal tumors and benign anal and pelvic floor disorders.
• The technique is minimally invasive, easy to perform with a short learning curve, and offers high-resolution imaging of the anal region.

Purpose of the Study:

• To review the clinical applications and diagnostic accuracy of Anorectal Endosonography (AE) in various anorectal conditions.
• To highlight the utility of AE in diagnosing fecal incontinence, perianal fistulae, and staging rectal and anal tumors.

Main Methods:

• AE utilizes a rotating probe (5-16 MHz) inserted into the rectum for 360-degree visualization of the pelvic floor and sphincter complex.
• Three-dimensional imaging capabilities have recently been introduced.
• Comparison with surgical findings and endoanal magnetic resonance imaging (MRI) in specific indications.

Main Results:

• AE precisely identifies sphincter defects in fecal incontinence, correlating perfectly with surgical findings and outperforming MRI in visualizing the internal anal sphincter.
• AE accurately stages perianal fistulae, including those in Crohn's disease, with high concordance to surgical outcomes, proving essential for preoperative planning.
• AE is effective for staging local resectability of low rectal tumors (T0/T1) and superior to TNM classification for staging anal carcinoma, providing prognostic information.

Conclusions:

• Anorectal endosonography is a highly accurate, user-friendly imaging modality for assessing anal sphincter integrity and perianal fistulae.
• AE is particularly valuable in the diagnosis and management of anal incontinence and complex perianal fistulae.
• The technique demonstrates excellent utility in staging anal carcinoma and can aid in the evaluation of select rectal tumors.