From the Guidelines
The initial workup for a rectal abscess includes a thorough history and physical examination, focusing on digital rectal examination to identify the fluctuant, tender mass, and laboratory tests including complete blood count and basic metabolic panel should be obtained to assess for systemic infection, as suggested by the WSES-AAST guidelines 1. The diagnosis of a rectal abscess is typically made based on clinical presentation, which includes perianal pain, swelling, and fever, and the classification of fistulae depends on their anatomical location, as described in the study by the World Journal of Emergency Surgery 1.
Key Components of Initial Workup
- Thorough history and physical examination, including digital rectal examination
- Laboratory tests, including complete blood count and basic metabolic panel
- Imaging, such as CT scan or endoanal ultrasound, may be helpful in complex cases or when the abscess is not readily apparent on examination, as recommended by the ACR Appropriateness Criteria 1
Treatment
The definitive treatment for a rectal abscess is prompt surgical incision and drainage, which should not be delayed for antibiotics or imaging, as recommended by the WSES-AAST guidelines 1. The procedure is typically performed under local anesthesia with sedation in an outpatient setting, creating an adequate opening to allow complete drainage of purulent material.
Antibiotic Therapy
Antibiotics alone are insufficient treatment but should be added for patients with systemic signs of infection, immunocompromise, diabetes, or extensive cellulitis, as suggested by the study on anorectal emergencies 1. Appropriate empiric antibiotic choices include trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 double-strength tablets twice daily, clindamycin 300-450mg four times daily, or amoxicillin-clavulanate 875/125mg twice daily for 5-7 days.
Post-Procedure Care
Post-procedure care includes sitz baths 2-3 times daily, analgesics such as acetaminophen or NSAIDs, and maintaining soft stools with fiber supplements. Patients should be informed that approximately 30-50% of anorectal abscesses may develop into fistulas requiring additional treatment, as described in the study by the World Journal of Emergency Surgery 1.
From the Research
Initial Workup for Rectal Abscess
- The initial workup for a rectal abscess typically involves a physical examination, complete blood count, and imaging studies such as ultrasound, CT scan, or MRI to confirm the diagnosis and determine the size and location of the abscess 2, 3, 4.
- Laboratory tests, including blood cultures and stool studies, may also be ordered to identify the underlying cause of the abscess and to guide antibiotic therapy 5, 6.
Treatment of Rectal Abscess
- The primary treatment for a rectal abscess is incision and drainage (I&D), which involves surgically draining the abscess to relieve symptoms and prevent further complications 2, 5.
- Antibiotic therapy is often used in conjunction with I&D to treat the underlying infection and prevent recurrence 2, 3, 5, 6.
- The choice of antibiotic regimen depends on the severity of the infection, the presence of underlying medical conditions, and the results of culture and sensitivity testing 3, 6.
Antibiotic Regimen
- A study published in 2020 found that inadequate antibiotic coverage after I&D of complicated peri-rectal abscess resulted in a six-fold increase in the re-admission rate 2.
- Another study published in 2011 found that only 23% of patients had appropriate antibiotic selection with optimal concentrations for the bacteria recovered from abdominal abscesses 3.
- A systematic review and meta-analysis published in 2019 found that antibiotic therapy following incision and drainage of anorectal abscesses was associated with a 36% lower odds of fistula formation 5.
Special Considerations
- In patients with Crohn's disease, the management of abdominal abscesses may involve a combination of antibiotic therapy, percutaneous drainage, and surgical intervention 4, 6.
- The choice of therapeutic approach depends on the size and location of the abscess, the presence of fistulas or other complications, and the patient's overall health status 4, 6.