From the Guidelines
Surgical incision and drainage is the definitive treatment for perirectal abscess, and it should be performed promptly to prevent complications. The procedure involves making an incision over the abscess, evacuating the pus, and leaving the wound open to heal by secondary intention 1. Local anesthesia is typically sufficient, though larger or deeper abscesses may require regional or general anesthesia.
Diagnosis
The diagnosis of perirectal abscess is primarily clinical, based on symptoms such as pain, redness, and swelling in the perianal area, as well as systemic signs of infection like fever and elevated white blood cell count 1. Imaging studies like MRI, CT scan, or endosonography may be used in cases with atypical presentation, suspicion of occult supralevator abscesses, complex anal fistula, or perianal Crohn’s disease 1.
Treatment
Antibiotics alone are not adequate treatment but may be added for patients with systemic symptoms, immunocompromise, diabetes, valvular heart disease, or extensive cellulitis 1. When antibiotics are needed, options include amoxicillin-clavulanate 875/125 mg twice daily, trimethoprim-sulfamethoxazole DS twice daily plus metronidazole 500 mg three times daily, or ciprofloxacin 500 mg twice daily plus metronidazole, typically for 7-10 days.
Post-Procedure Care
Post-procedure care includes:
- Sitz baths 2-3 times daily
- Regular dressing changes
- Pain management with acetaminophen or NSAIDs Patients should follow up within 1-2 weeks and should be informed that approximately 30-50% of perirectal abscesses may develop into anal fistulas requiring additional treatment 1. Recurrent abscesses warrant evaluation for underlying conditions like inflammatory bowel disease, HIV, or malignancy.
Key Considerations
- The timing of surgery is dictated by the patient’s clinical condition and comorbidities, with emergent drainage required in cases of sepsis, severe sepsis, septic shock, immunosuppression, diabetes mellitus, and diffuse cellulitis 1.
- The role of wound packing after anorectal abscess drainage remains unproven, and its use should be left to individual unit policy and patient discussion 1.
From the Research
Diagnosis of Perirectal Abscess
- Perirectal abscesses can be diagnosed through a combination of clinical presentation, physical examination, and imaging studies 2, 3, 4, 5.
- The most common presenting symptom of perirectal abscess is perirectal pain, which is 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 computed tomography (CT) and transperineal ultrasound can be used to diagnose perirectal abscesses, especially in cases where the abscess is deep or complex 3, 4, 5.
- CT scans have a sensitivity of 77% in detecting perirectal abscesses, but may be less sensitive in immunocompromised patients 5.
Treatment of Perirectal Abscess
- The primary treatment for perirectal abscess is early and adequate drainage, which can be performed through incision and drainage or other surgical methods 2, 6.
- Antibiotics may be used as adjunct therapy, but are not always necessary and may not be effective against all types of bacteria, such as MRSA 2, 6.
- The use of antibiotics should be guided by culture results and sensitivity testing, especially in cases where MRSA is suspected 6.
- MRSA is a prevalent and underrecognized pathogen in perirectal abscesses, and may require specific antibiotic coverage 6.
Imaging Studies
- CT scans are a useful tool for diagnosing perirectal abscesses, especially in the emergency room setting 3.
- Transperineal ultrasound is an emerging imaging modality for diagnosing perineal and perianal abscesses, and may be useful in cases where CT is not available or contraindicated 4.
- Magnetic resonance imaging (MRI) is the best imaging test for detecting fistulous tracts, especially complex ones, but may not be readily available in all settings 3.