Transperineal sonography in anorectal disorders

Magnetic resonance imaging, computed tomography, endorectal and endoanal sonography are used for imaging of inflammatory and neoplastic conditions of the lower rectum, the anus and the perineum. These methods, however, have their limitations regarding accuracy, cost-effectiveness, and availability in the acute setting. Pain may be a limiting factor when introducing a probe into the anus. Percutaneous transperineal sonography is an acknowledged method for diagnosing anorectal malformations in children and infants and for diagnosis of prostatic disease. Until today, only limited reports regarding the value of transperineal sonography for evaluation of diseases of the lower rectum, the anus and the perianal region in adults are available. Between 1997 and 2000 a total of 44 patients underwent transperineal sonography including B-mode and colour Doppler sonography for imaging anorectal structures using 3.5 MHz sector arrays and 7 MHz linear arrays. The lesions were also investigated using colour Doppler imaging. During examination the patient is positioned on his side. Orientation landmarks are the pubic symphysis and the prostate gland in men and the vagina in women. The spectrum of diseases of the current study population (44) included perianal fistulas (10), pararectal abscesses (7), fistulas with abscess (7), perianal inflammation without abscess (1), rectal (6) and anal carcinomas (3) and metastasis of a leiomyosarcoma (1). In 10 cases digital examination of the anus and rectum was not possible because of intense pain. In 34 patients (85 %) sonographic findings were confirmed by intraoperative diagnosis. Transperineal sonography proved to be an inexpensive, easily available diagnostic tool that may help in detecting a variety of pathological conditions of the lower rectum, the anus, and the perianal region.