Horseshoe Ischiorectal Abscess Originating from Dorsal Intersphincteric Cryptoglandular Abscess

Abstract

A 68-year-old man presented with severe perianal pain. Previous history, apart from medication-controlled hypertension, was unremarkable. He appeared well but in pain. His temperature was 100°F and there were no signs of generalized sepsis. Perianal skin induration was present except anteriorly. The point of maximum tenderness was found on the left lateral buttock some 7 cm from the anal verge. Rectal examination revealed tenderness and perirectal swelling that was most severe in the posterior commissure. Anal endosonography taken 2 cm from the anal verge showed a cryptoglandular intersphincteric abscess located dorsally (P) between the internal and sphincter (open arrow, 11 o’clock) and the external anal sphincter (closed arrow, 3 o’clock). This abscess had perforated the external and sphincter (I), giving rise to a massive horseshoe ischiorectal abscess (bilateral curved open arrows). The abscess was drained through multiple incisions. The internal anal opening of the fistulous abscess was identified and a staged seton management was performed. Pus culture showed multiple strains of anaerobes. Adequate drainage was achieved and the horseshoe abscess cavity healed. Eight weeks later the seton was removed. The wound was left to heal by secondary intention. Six months after the last operation, the patient was continent to solid and liquid stool, although there was some soiling and increased urge to defecate. There was no recurrent perianal sepsis.