Anorectal Abscess Flashcards
What is a anorectal abscess?
An anorectal abscess refers to a collection of pus in the anal or rectal region.
Who is commonly affected by an anorectal abscess?
They are more common in men than in women and have high rates of recurrence.
Briefly describe the pathophysiology of an anorectal abscess
Anorectal abscess are though to be caused by plugging of the anal ducts, the ducts that drain the anal glands in the anal wall, helping to ease the passage of faecal matter through mucus secretion.
Blockage of an anal duct results in fluid stasis, which will lead to infection. Common causative organisms include E. coli, Bacteriodes spp. and Enterococcus spp..
Where are the anal glands located?
The anal glands are located in the intersphincteric space (between the internal and external anal sphincters), therefore infection from the glands here spreads to adjacent areas.
Where are the 4 locations in which anorectal abscesses can form?
Anorectal abscesses are thus categorised by the area (Fig. 1) in which they occur:
- Perianal
- Ischiorectal
- Intersphincteric
- Supralevator
Where are the majority of anorectal abscesses formed?
The perianal area is the most common site of abscess formation.
What are the clinical features of an anorectal abscess?
Anorectal abscesses present with pain in the perianal region, which becomes exacerbated when sat down. Other symptoms include localised swelling, itching or discharge. Severe abscesses may present with systemic features such as fever, rigors, general malaise, or features of sepsis.
On examination, there will be a erythematous, fluctuant, tender perianal mass, which may be discharging pus or have surrounding cellulitis.
Deeper abscesses may not have any obvious external signs, however produce severe tenderness on digital rectal exam, therefore require a further examination under anaesthesia for full assessment.
What iadditional imaging modalities can be used to assess complicated, unclear or chronic disease?
Complicated, unclear, or chronic disease may require additional imaging, either a CT or MRI scan.
Briefly describe the management of an anorectal abscess
Patients should be started on antibiotic therapy, as guided by local protocol, and provided with sufficient analgesia.
The main management for anorectal abscesses is with an incision and drainage procedure, which should always be performed under general anaesthetic. These can be left to heal by secondary intention.
Once drained, proctoscopy should be performed to check for the presence of any identifiable fistula-in-ano. If a fistula is identified, the insertion of a seton can be considered by experienced surgeons, however this should only be performed if the tract is clearly identifiable with minimal probing.
