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Anorectal abscess: Management guideline updates by WSES and AAST

M3 India Newsdesk Apr 28, 2022

Guidelines from the World Society of Emergency Surgery (WSES) and the American Association for the Surgery of Trauma (AAST) provide key recommendations for the management of anorectal abscesses which have been penned down in this article.

What is an anorectal abscess?

An anorectal abscess is a painful infection in the soft tissue around the anus. Based on the location of the infection, the clinical manifestation and management strategy may vary. Surgical drainage is the main treatment for anorectal abscesses. The majority of anorectal abscesses are idiopathic in nature, however, some may present as part of other conditions such as Crohn’s disease. Based on the location of the infection, the clinical manifestation and management strategy may vary.

Clinical examination and biochemical investigations in suspected anorectal abscess

Complete physical examination and a focused medical history should be carried out. Physical examination, including a digital rectal examination, should include an analysis of the perineum for:

  • Surgical scars
  • Anorectal deformities
  • Signs of perianal Crohn’s disease
  • Secondary cellulitis
  • External opening of an anal fistula

Laboratory tests are not routinely required but may be used in specific situations. Laboratory tests should be carried out after considering the clinical findings. It can help assess the severity of the infection, especially in patients showing haemodynamic instability and those requiring emergency surgery.

In patients with suspected anorectal abscess, serum glucose, haemoglobin A1c, and urine ketones should be checked to identify undetected diabetes mellitus. In patients with signs of systemic infection or sepsis, a complete blood count, serum creatinine, and inflammatory markers (e.g., C-reactive protein, procalcitonin, and lactates) should be carried out.

The symptoms of anorectal abscesses may be absent or diminished in older and debilitated patients, in patients with diabetes or other forms of immunosuppression, and in some cases of associated necrotising soft-tissue infection. Hence, these patient groups should be treated using an aggressive approach with a great degree of suspicion.

Imaging investigations in patients with a suspected anorectal abscess

Radiological studies are not routinely required, but may be used in specific situations such as those with an atypical presentation (e.g., lower back pain, severe anal pain in the absence of a fissure, urinary retention), when the physical examination suggests a supra levator or intersphincteric abscess or when there is suspicion of perianal Crohn’s disease.

Computerised tomography (CT), magnetic resonance imaging (MRI) and endoscopic ultrasound (EUS) are some imaging techniques that can be used in the diagnosis of perianal abscesses. These techniques can also help exclude related conditions and accurately identify the regional anatomy and extent of the disease. Imaging techniques should be chosen considering the patient’s past medical history, clinical presentation, local availability of resources, and skills.

Surgery in patients with an anorectal abscess

Surgical drainage is the main treatment for anorectal abscesses. A surgical approach with incision and drainage is recommended. The timing of the surgery depends on the severity and nature of any sepsis. Due to the high recurrence rate and the associated risk factors, complete and accurate drainage of the abscess is necessary. In fit, immunocompetent patients with a small perianal abscess and without systemic signs of sepsis, outpatient management is suggested.

Role of wound packing after surgical drainage

No recommendation has been made regarding the use of packing after drainage of an anorectal abscess.

Fistula treatment in the acute setting in patients with an anorectal abscess with a concomitant fistula

In patients with anorectal abscess and an obvious fistula, it is suggested to perform a fistulotomy at the time of abscess drainage only in cases of low fistula not involving sphincter muscle (i.e., subcutaneous fistula). It is suggested to place a loose draining seton in patients with anorectal abscess and an obvious fistula involving any sphincter muscle.

In patients with anorectal abscess and no obvious fistula, probing to search for a possible fistula is not recommended. This would help prevent possible iatrogenic complications.

Antibiotic therapy in patients with an anorectal abscess

In anorectal abscess, cultures of drained pus are usually not required. However, there is a possibility for the presence of methicillin-resistant Staphylococcus aureus (MRSA) in routine anorectal abscesses. Hence, sampling of drained pus should be carried out in cases with:

  • Risk factors for multidrug-resistant organism (MDRO) infection
  • Recurrent infections
  • Non-healing wounds
  • In high-risk patients (e.g., HIV, immunocompromised patients, etc.)

In patients with drained anorectal abscess, antibiotics administration is suggested in the presence of sepsis and/or surrounding soft tissue infection or in case of disturbances of the immune response. The WSES guidelines for soft-tissue and intra-abdominal infections should be referred for more details on the appropriate antibiotics regimens.

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Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.

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