From the Guidelines
A perirectal abscess is a painful collection of pus near the rectum that requires prompt treatment, typically through surgical incision and drainage, as recommended by the most recent guidelines 1. The diagnosis of a perirectal abscess is primarily based on clinical examination and medical history, including a digital rectal examination, and may involve biochemical investigations such as serum glucose, hemoglobin A1c, and urine ketones to identify undetected diabetes mellitus 1. Imaging investigations like MRI, CT scan, or endosonography may be suggested in cases of atypical presentation or suspicion of complex conditions 1.
Treatment Approach
The primary treatment for anorectal abscesses is surgical drainage, with the timing based on the presence and severity of sepsis 1. In patients with an anorectal abscess, a surgical approach with incision and drainage is strongly recommended 1. For fit, immunocompetent patients with a small perianal abscess and no systemic signs of sepsis, outpatient management may be considered 1.
Post-Drainage Care
Following drainage, patients should take sitz baths 2-3 times daily for 10-15 minutes using warm water. Pain management typically includes acetaminophen 650mg every 6 hours and/or ibuprofen 600mg every 8 hours as needed.
- The use of antibiotics is suggested in the presence of sepsis, surrounding soft tissue infection, or disturbances of the immune response 1.
- When prescribed, common regimens include amoxicillin-clavulanate 875/125mg twice daily for 5-7 days or, for penicillin-allergic patients, clindamycin 300mg four times daily 1.
Follow-Up
Patients should follow up within 1-2 weeks and return sooner if they develop increasing pain, fever, spreading redness, or purulent discharge. Perirectal abscesses can progress to fistulas or deeper tissue infections without proper treatment, making timely intervention essential.
Additional Considerations
- The role of wound packing after surgical drainage remains unproven, with some studies suggesting it may not add benefit to the healing process 1.
- Sampling of drained pus is suggested in high-risk patients or those with risk factors for multidrug-resistant organism infection 1.
From the Research
Diagnosis of Perirectal Abscess
- The diagnosis of perirectal abscess is primarily based on clinical presentation, with perirectal pain being the most common symptom, present in 98.9% of cases 2.
- External perianal and digital rectal examination can identify an abscess in 94.6% of patients 2.
- Imaging studies, such as abdominal contrast-enhanced computed tomography (CT), can also be used to confirm the diagnosis and identify any complications, such as extension into the space of Retzius 3.
Treatment of Perirectal Abscess
- The primary treatment for perirectal abscess is incision and drainage (I&D), which is effective in resolving the abscess in all patients 2.
- Antibiotics may be used as adjunct therapy, but their use is not always necessary and should be tailored to the specific patient and type of infection 2, 4.
- In cases where antibiotics are used, a standard oral protocol combining antibiotics covering typical gram-positive, gram-negative, and anaerobic organisms may provide adequate coverage after surgical drainage 4.
- Postoperative antibiotics have been shown to reduce the risk of fistula formation after incision and drainage of anorectal abscesses, with a 36% lower odds of fistula formation 5.
Complications and Management
- Complications of perirectal abscesses can include formation of extensive abscesses, urine retention, and recurrence 2.
- Inadequate antibiotic coverage after I&D of complicated peri-rectal abscess can result in a higher re-admission rate for abscess recurrence 4.
- A multidisciplinary approach, including prompt diagnosis, appropriate antibiotic therapy, and timely surgical interventions, is crucial for successful management of complex anorectal abscesses 3.
- Fistula management requires striking a balance between rates of healing and potential alteration of fecal continence, and many techniques are available for treatment 6.