Fistulotomy produces a satisfactory outcome in terms of eradicating sepsis and preserving function in the vast majority of patients with intersphincteric fistula with intact sphincters. However, sphincter-preserving treatment may be advocated for patients with low preoperative voluntary contraction pressure or those who have undergone multiple drainage surgeries. Preoperative anal manometry is useful in determining the proper surgical procedure.

Non-sphincter splitting fistulectomy for high trans-sphincteric fistula provided better functional results than fistulotomy. Less impairment of anal continence was achieved possibly not only by maintenance of the external anal sphincter function but also by preservation of the length of the high-pressure zone.

We report two cases of perianal endometriosis in which we were greatly assisted by endoanal ultrasonography. Patient 1 was a 43-year-old woman with perianal pain. Endosonography showed a hypoechoic mass in the anterior perianal region without involvement of the anal sphincter. Local excision was performed under spinal anesthesia without damage to the anal sphincter. Patient 2 was a 30-year-old woman with perianal pain coinciding with her menstrual period. Endosonography showed a heterogeneous mass containing cystic anechoic areas in the right anterior perianal region and involving the external anal sphincter. Wide excision, including the episiotomy scar and part of the external anal sphincter, and primary sphincteroplasty were performed under spinal anesthesia. According to our experience, preoperative endosonography is a reliable technique for visualizing perianal endometriosis and for diagnosing anal sphincter involvement. Operative management should be determined on the basis of preoperative and intraoperative ultrasonographic assessment.

Endoanal ultrasonography is reliable and useful for preoperative assessment of anal fistula, particularly for detecting horseshoe extension and localizing the internal opening. Endosonographic assessment provides clearer depiction of the internal opening during periods of quiescence than during the period of abscess formation. For patients with acute anorectal sepsis, initial surgical drainage and subsequent fistula surgery, rather than one-stage fistula surgery, may be advisable to avoid misidentification of the internal opening.

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