Treatment of Rectal Abscess

Surgical incision and drainage is the definitive treatment for all rectal abscesses. 1

Diagnosis and Assessment

A focused medical history and complete physical examination, including digital rectal examination, should be performed to diagnose a rectal abscess 1
Check for undetected diabetes mellitus by measuring serum glucose, hemoglobin A1c, and urine ketones, as diabetes is a common comorbidity in patients with anorectal abscesses 1
For patients with signs of systemic infection or sepsis, request complete blood count, serum creatinine, and inflammatory markers (C-reactive protein, procalcitonin) 1
Imaging (MRI, CT scan, or endosonography) is not routinely required but should be considered in cases of atypical presentation, suspected occult supralevator abscesses, or perianal Crohn's disease 1

Incision and drainage is the cornerstone of treatment for all rectal abscesses 1, 2
Timing of surgery should be based on the presence and severity of sepsis 1
For deeper or more complex abscesses, more extensive drainage may be required, potentially with multiple counter incisions 1
In infants with perianal abscesses, the incision should be kept as close as possible to the anal verge to minimize potential fistula length while ensuring adequate drainage 3

If a low fistula not involving sphincter muscle (subcutaneous fistula) is identified, fistulotomy can be performed at the time of abscess drainage 1
For fistulas involving sphincter muscle, place a loose draining seton rather than performing immediate fistulotomy to prevent incontinence 1, 2
Avoid probing to search for a fistula if one is not obvious, as this may cause iatrogenic complications 1

Antibiotics are not routinely indicated for adequately drained anorectal abscesses in immunocompetent patients 1
Antibiotic administration is recommended in the following scenarios:
- Presence of sepsis 1
- Immunocompromised patients 1
- Significant surrounding soft tissue infection 3
- Incomplete source control 3
- Complicated peri-rectal abscesses (as inadequate antibiotic coverage can result in a six-fold increase in readmission rates) 4
When indicated, empiric broad-spectrum antibiotic therapy should cover Gram-positive, Gram-negative, and anaerobic bacteria 1, 4
Consider sampling of drained pus in high-risk patients or those with risk factors for multidrug-resistant organisms 1

No definitive recommendation can be made regarding wound packing after drainage based on current evidence 1
Close follow-up is essential to monitor for recurrence or fistula development 3, 2
Regular evaluation of drainage is essential to monitor treatment response and healing progress 5

Necrotizing soft-tissue infection is a rare but serious complication of rectal abscess requiring aggressive therapy, including frequent examinations under anesthesia, wide debridement, systemic triple antibiotic therapy, diverting colostomy, aggressive wound care, and hyperalimentation 6
Fistula formation varies from 25% to 50% after anorectal abscesses and is much more common with gut-derived organisms (e.g., E. coli, B. fragilis) 7
Inadequate drainage is associated with high recurrence rates 3, 4