What are the potential complications after drainage of a perirectal abscess?

Potential Complications After Drainage of Perirectal Abscess

The most significant complications after drainage of perirectal abscess include recurrent abscess formation, fistula development, and potential anal function disturbances, with recurrence rates as high as 44% in some cases. 1

Common Complications

Recurrence and Fistula Formation

• Recurrence rates after drainage can reach up to 44%, with risk factors including inadequate drainage, loculations, horseshoe-type abscess, and delayed time from disease onset to incision 1
• Approximately one-third of perianal abscesses may develop a fistula-in-ano, which significantly increases the risk of abscess recurrence requiring repeat surgical drainage 1, 2
• Fistula formation occurs in 16-24% of patients after drainage, with slightly lower rates (16% vs 24%) in those receiving postoperative antibiotics 1
• Reoperation rates of approximately 3.4% have been reported, with the majority (79.7%) performed for additional incision and drainage due to inadequate initial drainage 3

Anal Function Disturbances

• Primary fistulectomy with partial internal sphincterotomy performed at the time of abscess drainage can reduce recurrence rates but is associated with increased anal function disturbances 1
• Transient reduction in anal sphincter pressures may occur after treatment of low fistulae with abscess drainage 2
• Risk of incontinence increases when fistulas involving sphincter muscles are treated at the time of abscess drainage 1

Infection-Related Complications

• Readmission rates of approximately 3.0% have been reported, with common indications including recurrent/persistent abscess (41.4%) and fever/sepsis (8.6%) 3
• Surrounding soft tissue infection may develop, particularly in patients with inadequate drainage or those with compromised immune systems 1
• Progression to systemic infection or sepsis can occur, especially in immunocompromised patients 1

Rare but Serious Complications

• Progression to Fournier's gangrene (perineal necrotizing fasciitis) in severe cases, particularly in patients with diabetes or immunosuppression 1
• Bacteremia and septic shock in patients with inadequate drainage or delayed treatment 1

Risk Factors for Complications

• Preoperative sepsis, bleeding disorders, morbid obesity, and dependent functional status increase risk of prolonged hospitalization and reoperation 3
• Female sex, steroid/immunosuppression use, and dependent functional status are significant risk factors for readmission 3
• Immunosuppression, diabetes mellitus, and presence of systemic sepsis increase complication risks 1
• Inadequate initial drainage technique is a major risk factor for recurrence 1

Prevention Strategies

• Complete and thorough drainage of the abscess cavity is essential to prevent recurrence 1
• Consider antibiotic administration in patients with sepsis, surrounding soft tissue infection, or immune system disturbances 1
• For patients with an obvious fistula, place a loose draining seton if there is sphincter muscle involvement rather than attempting immediate fistulotomy 1
• Avoid probing to search for a possible fistula during abscess drainage to prevent iatrogenic complications 1
• Consider sampling of drained pus in high-risk patients or those with risk factors for multidrug-resistant organism infection 1

Special Considerations

• In patients with recurrent abscesses, imaging (MRI, CT, or endosonography) may be necessary to identify complex fistulas or occult supralevator abscesses 1
• Patients with inflammatory bowel disease, particularly Crohn's disease, have higher risks of complications and may require specialized management approaches 4
• Recent evidence suggests that emergency room incision and drainage can be equivalent to operating room procedures for uncomplicated cases, with similar complication rates 5