Perianal abscess Flashcards
What is a perianal abscess?
A perianal abscess is a collection of pus within the subcutaneous tissue of the anus that has tracked from the tissue surrounding the anal sphincter.
What is the epidemiology of perianal abscesses?
They are the most common form of anorectal abscess, making up around 60% of cases; more common in men (M:F 2:1); average age of patients is around 40 years.
What are the features of a perianal abscess?
Patients may describe pain around the anus, which may be worse on sitting; hardened tissue in the anal region; pus-like discharge from the anus; features of systemic infection if longstanding.
What are the common causes of perianal abscesses?
They are generally colonised by gut flora such as E. coli; infections caused by organisms like Staph. aureus are more likely to originate from the skin.
How are perianal abscesses investigated?
Most can be detected through inspection and digital rectal examination; colonoscopy and blood tests may help query underlying causes; MRI is the gold standard for imaging.
What associated conditions can lead to perianal abscesses?
Underlying inflammatory bowel disorders, especially Crohn’s; diabetes mellitus affects wound healing; underlying malignancy can cause abscesses and anorectal lesions.
What is the treatment for a perianal abscess?
Treatment is usually surgical, with incision and drainage being first line; antibiotics are used if there is systemic upset, but do not help with wound healing after drainage.
What are the types of anorectal abscesses?
Ischiorectal abscesses are between the obturator internus muscles and external anal sphincter; supralevator abscesses track superiorly from the peri-sphincteric area; intersphincteric abscesses are rare (2-5% of cases); horseshoe abscesses are found between the coccyx and anal canal.
