Ischiorectal abscess is deeper, extending across the sphincter into the ischiorectal space below the levator ani; it may penetrate to the contralateral side, forming a “horseshoe” abscess. An abscess above the levator ani (ie, supralevator abscess) is quite deep and may extend to the peritoneum or abdominal organs; this abscess often results from diverticulitis or pelvic inflammatory disease.
Ischiorectal fossa lies between anal skin and levator ani. Right and left communicates with each other. Laterally, it is related to fascia covering obturator internus; medially to levator ani and external sphincter; posteriorly sacrotubercous ligament and gluteus maximus; anteriorly urogenital diaphragm; below, the floor by skin.
Above it is related to lunate fascia and pudendal neurovascular bundle in pudendal canal (Alcock’s canal)
- Commonly, it is due to extension of low intermuscular anal abscess, laterally through external sphincter
- But often it can be blood or lymphatic born.
- Fat in the fossa is more prone for infection because it is least vascularised
- Fossa communicates with that of opposite side through postsphincteric space and so horse-shoe like abscess can occur.
- It presents with tender, indurated, brawny swelling in the skin over the ischiorectal fossa with high fever.
- Swelling is not well-localised and fluctuation is absent in ischiorectal abscess.
- painful; perianal swelling, redness, and tenderness are characteristic.
- CT SCAN
- CLINICAL EXAMINATION
- PELVIC MRI
- Merc Sol