Vulvar Abscess

A vulvar abscess is a collection of pus in the vulval soft tissue not arising from the Bartholin gland. It comes from infected hair follicles, sebaceous cysts, skin injury, episiotomy or an infected haematoma.

• Organisms are S. aureus (including MRSA), streptococci and anaerobes.
• It requires drainage; antibiotics alone fail.
• Diabetes, HIV, obesity and immunosuppression raise the risk of spreading infection.

Painful, hot, red, fluctuant swelling in the labia, perineum or mons.

• Fever, malaise, difficulty walking and sitting, urinary retention if the abscess is near the urethra.
• Differential diagnosis: Bartholin abscess, furuncle, infected epidermal inclusion cyst, hidradenitis suppurativa, vulval cellulitis, infected haematoma, Skene gland abscess, vulval Crohn disease.
• Complications: necrotising fasciitis, septicaemia, fistula, scarring, recurrence.

Diagnosis is clinical, with culture of pus and tests for risk factors.

• Clinical diagnosis.
• Pus for Gram stain, culture and sensitivity.
• Full blood count, random blood glucose, HIV test, urea and creatinine in sick patients.
• Ultrasound when the extent is unclear or a deep collection is suspected.
• Swabs for gonorrhoea and chlamydia if the location is near the Bartholin or Skene gland.

Drain the abscess, give antibiotics for cellulitis or risk factors, and treat predisposing conditions.

• Supportive: warm sitz baths after drainage, 10 to 15 minutes, 3 to 4 times daily; adequate fluids; dressing changes; rest.
• Pharmacological:
  • Analgesia with paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours) with ibuprofen 400 mg oral 8-hourly with food for 5 days (maximum 1.2 g in 24 hours).
  • Antibiotics when there is cellulitis, fever, diabetes, HIV infection or large abscess: amoxicillin-clavulanate 625 mg oral 8-hourly for 5 to 7 days (child 15 mg/kg of amoxicillin component 8-hourly, maximum 500 mg per dose).
  • Penicillin allergy or MRSA: clindamycin 300 mg oral 8-hourly for 5 to 7 days (child 3 to 6 mg/kg 6-hourly, maximum 450 mg per dose).
  • Severe infection: ceftriaxone 1 g IV daily (child 50 mg/kg daily, maximum 2 g) plus metronidazole 500 mg IV 8-hourly (child 7.5 mg/kg 8-hourly) until afebrile for 24 hours, then oral treatment to complete 7 days.
  • Give tetanus toxoid 0.5 mL IM if the wound is contaminated and tetanus immunisation is incomplete.
• Procedures: incision and drainage under 1 percent lignocaine (maximum 3 mg/kg, absolute maximum 200 mg plain) or general anaesthesia if large; break loculi, irrigate with saline, and leave the cavity open with a light pack removed at 24 to 48 hours. Send the wall for histology in women above 40 years.
• Special groups: in pregnancy avoid doxycycline, avoid co-trimoxazole in the first trimester and avoid ibuprofen from 28 weeks. In diabetes keep blood glucose at 6 to 10 mmol/L with insulin.
• Red flags: pain out of proportion, crepitus, skin necrosis, rapid spread, hypotension, fever above 38.5 degrees Celsius.
• Follow-up: dressing review at 48 hours and 1 week; refer for investigation of hidradenitis suppurativa or Crohn disease if recurrent.