Perianal abscess

Disease Description (Causes and Symptoms)

• Definition and pathophysiology: A perianal abscess is an acute suppurative inflammation in which pus accumulates in the area due to obstruction of the intra-anal (anal) glands and bacterial invasion. There are several anal glands around the inner wall of the anal canal, and the usual progression is duct obstruction → accumulation of secretions → bacterial proliferation → abscess formation.
• Main causes: Infection with intestinal bacteria (such as Escherichia coli) is the most common cause. Inflammatory bowel diseases such as ulcerative colitis and Crohn’s disease, tuberculosis, radiation injury, pelvic inflammatory disease, trauma, malignant tumors, lymphogranuloma venereum, and immunosuppression (such as leukemia and diabetes) may act as contributing factors.
• Symptoms: Local redness, swelling, and tenderness; severe anal pain (especially when sitting or defecating); fever; and discharge of pus or other fluid from the affected area. A superficial abscess may show visible swelling and pus, while a deep abscess may cause only pain and fever without external swelling. Recurrent abscesses may leave a small opening (fistula or sinus) around the anus. (Based on the clinical course, more than approximately 50% may progress to an anal fistula.)

Treatment Methods and Precautions

• Acute treatment (standard treatment):
  • Drainage (incision and drainage): This is the most important treatment for relieving pain, and adequate drainage is performed under appropriate anesthesia. Drainage is the basic principle; delaying it carries a high risk of worsening pain and infection.
  • Antibiotics: Drainage alone is often sufficient for a simple superficial abscess, but empirical antibiotics (covering gram-negative bacteria and anaerobes — for example, amoxicillin/clavulanate, or ciprofloxacin + metronidazole) are added when there are systemic symptoms (high fever), immunosuppression, diabetes, suspected extensive soft-tissue infection, or severe surrounding inflammation. If the risk of MRSA is high, an appropriate antibiotic must be selected (for example, doxycycline or clindamycin, taking local susceptibility into consideration).
  • Pain relievers, sitz baths, and measures to facilitate bowel movements (such as fiber, laxatives, or suppositories to prevent constipation)
• Treatment of chronic disease/complications:
  • If an anal fistula (fistula-in-ano) forms, surgical treatment (fistulotomy/fistula incision, seton placement, LIFT, sphincter-preserving rectal closure procedures, etc.) may be considered depending on the type of fistula (simple/complex). In complex fistulas or when there is substantial sphincter involvement, performing a fistulotomy indiscriminately carries a risk of incontinence, so specialist evaluation is necessary.
• Precautions and self-care:
  • Until drainage is performed, never forcibly squeeze or press on the abscess at home (risk of spreading the infection).
  • Wound care: Maintain cleanliness through sitz baths and dressings until drainage stops. If persistent discharge continues after drainage, outpatient follow-up/reassessment is necessary.
  • High-risk groups (people with diabetes or immunosuppression) have a higher risk of complications (deep infection and sepsis), so early treatment and monitoring are important.
• Emergency warning signs (immediate medical care/emergency department visit recommended):
  • High fever or chills; rapidly worsening pain; an abscess that becomes substantially larger, with rapidly spreading redness or poorly demarcated soft-tissue inflammation (suspected cellulitis); or systemic symptoms (such as dizziness or low blood pressure)

Checklist Before an Outpatient Visit (Including Items to Bring and Example Questions)

• Items/information to prepare:
  • Current medications and allergies (especially to antibiotics and anesthetics)
  • History of previous anal surgery, abscesses, or fistulas
  • Presence of chronic diseases (diabetes, immunosuppressive treatment, inflammatory bowel disease, etc.)
  • When symptoms began, changes in pain intensity, presence of fever, and the color, amount, and odor of the discharge
  • Whether you are taking anticoagulants (for bleeding-risk assessment)
  • Bring recent test results (blood tests, abdominal/pelvic imaging, etc.) or a medical certificate from another hospital, if available
• Items useful to record for the outpatient visit:
  • Changes in bowel habits (bloody stool, mucus, etc.), weight changes, and whether there is nighttime pain
  • Factors that worsen or relieve symptoms (such as improvement after a sitz bath)

General Example Questions to Ask the Doctor

• "Does my current condition require surgical drainage? Do I need to go to the emergency department?"
• "What should I do if I am taking medications such as anticoagulants or immunosuppressants?"
• "What is the expected duration of the prescribed antibiotics, and what side effects should I watch for?"
• "How long does recovery after treatment usually take (improvement in pain and wound healing)?"
• "What lifestyle precautions should I take to reduce the risk of recurrence?"

Examples of Condition-Specific Questions

• "How likely is it that this abscess will progress to an anal fistula? (What are my individual risk factors?)"
• "If the abscess recurs or a fistula develops, what alternative surgical methods are available (including sphincter-preserving methods)? What is the risk of incontinence?"

(Note: The information above is general medical information. Specific diagnosis and treatment should be decided in consultation with the treating physician according to the individual’s condition.)