Although they represent a common ED problem, perirectal and perianal abscesses are frequently misdiagnosed and inappropriately treated. Delayed or inappropriate treatment may lead to increased morbidity and mortality. Perirectal abscesses likely arise from infection of the mucus-secreting anal glands, which drain into the anal crypts. Blockage of the duct is believed to be the initiating cause of the infection. The infection may then spread into other spaces in the area, to include the intersphincteric, ischiorectal, and supralevator spaces.
Perirectal abscesses are generally polymicrobial aerobic and anaerobic infections.
B. fragilis is the predominate anaerobe. Other common bacteria include E. coli , and those of the genera, Proteus , Bacteroides and Streptococcus . Sources of the bacteria are the skin, bowel and, rarely, the vagina. Bacteremia and sepsis can result, especially in the immunocompromised patient. Fournier's gangrene has occasionally been reported.