Perineal hernias are rare pelvic hernias, occurring through a defect in the pelvic floor musculature.
More common in females, with peak age of presentation between 40 and 60 years.
Perineal hernias are classified as anterior or posterior depending on their relationship with the transverse perineal muscle. Anterior hernias are more common than posterior hernias, and occur almost exclusively in females.
Primary hernias are most commonly acquired, with rare congenital cases. Acquired causes include pregnancy (accounting for the increased incidence in females), obesity or long-standing ascites. Secondary hernias occur following extensive pelvic surgery such as pelvic exenteration.
Anterior hernias demonstrate herniation of bowel through the urogenital diaphragm.
Posterior perineal hernias are seen on CT as protrusion of loops of sigmoid colon or rectum into the ischiorectal fossa.