Intersphincteric perianal abscess

Case contributed by Chris O'Donnell
Diagnosis certain


Chronic anal fissure. Now presents with severe rectal pain, fever and elevated CRP / white cell count

Patient Data

Age: 30
Gender: Male

Large U-shaped fluid collection sitting between the internal and external anal sphincters with edema in the puborectalis muscle and mesorectal fat (together with slightly enlarged lymph nodes) as well as the presacral space.  Perianal and ischiorectal fat is normal.  Note extrinsic compression of the anal lumen, and T2 signal and swelling in the left posterior prostate with marked distension of the bladder indicative of urinary retention.

Case Discussion

Perianal sepsis occurs most commonly in patients with Crohn disease or diabetes. Infection enters the perianal spaces by way of a defect in the anal mucosa (in this case a chronic anal fissure) with gut organisms proliferating. If left untreated, these abscesses can point to the skin leading to a fistula between the anal canal and skin

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