Abstract
A 72-year-old man presented with the chief complaint of anal pain to his neighborhood physician, who manually removed a fish bone that had penetrated the anal wall. However, the patient presented with recurrent anal pain two months later, and was admitted to our hospital. Although the anal canal mucosa was intact, MDCT revealed a high-density linear shadow on the right side of the perianal space in the anal sphincter muscle, with no evidence of abscess formation. We believed that a piece of the fish bone that had been removed earlier remained in the perianal space and scheduled surgical removal of the bone fragment. With the patient under spinal anesthesia, we made a small incision on the dentate line and used a pair of forceps to explore the area near the external edge of the internal anal sphincter muscle. Finally, we found the residual bone fragment in the intersphincteric space and removed it. Seton drainage was performed on day 7 because a perianal abscess had formed beneath the mucosal incision. Subsequently, after a fistulectomy, the patient was discharged from the hospital on hospital day 49. A perianal foreign body is usually associated with the formation of a perianal abscess, and can be easily removed once the abscess cavity is opened. However, in this patient, we had to approach the intersphincteric space directly because the patient presented without evidence of a perianal abscess.
