Perineal Wound Infection

Perineal wound infection is infection of a tear or episiotomy repair after vaginal birth, ranging from superficial cellulitis to dehiscence, abscess and necrotising fasciitis.

• It occurs in about 1 to 10 percent of repairs.
• Risk factors include prolonged labour, instrumental delivery, third or fourth degree tears, diabetes, obesity, anaemia, prolonged rupture of membranes, poor hygiene, and haematoma.
• Organisms include Staphylococcus aureus, Group A Streptococcus, Escherichia coli, anaerobes and mixed flora.
• Necrotising fasciitis is rare but life-threatening.

Symptoms usually start 3 to 7 days after birth.

• Increasing perineal pain, swelling, redness and warmth around the wound.
• Purulent, offensive discharge from the repair.
• Fever, malaise and tachycardia.
• Wound gaping (dehiscence), with exposed sutures or separation of tissue.
• Perineal abscess or collection.
• Pain out of proportion to appearance, crepitus, skin discolouration, blistering, and rapid systemic deterioration suggest necrotising fasciitis.
• Differential diagnosis: haematoma, suture reaction, endometritis, urinary tract infection, mastitis, vulvovaginal candidiasis, and retained foreign body.
• Complications: dehiscence, abscess, fistula formation (rectovaginal), sepsis, necrotising fasciitis, chronic pain, dyspareunia and delayed healing.

Diagnosis is clinical, with swab culture and assessment of depth.

• Examine the perineum under good light: erythema, induration, discharge, dehiscence, haematoma, and rectal examination for deeper collection or sphincter involvement.
• Wound swab for culture and sensitivity.
• Full blood count, C-reactive protein, blood cultures if febrile, and lactate if unwell.
• Ultrasound or MRI for deep abscess.
• High suspicion for necrotising infection: urgent surgical review and operative exploration, with imaging only if it does not delay surgery.

Treatment is wound care and antibiotics, with surgery when needed.

• Supportive: analgesia, perineal hygiene (warm saline washes, drying with a hair dryer on cool setting), loose cotton underwear, sitz baths, avoid constipation, and pad changes frequently.
• Pharmacological, mild superficial infection (oral): amoxicillin-clavulanate 625 mg three times daily for 5 to 7 days, or cefalexin 500 mg four times daily with metronidazole 400 mg three times daily for 5 to 7 days.
• Moderate to severe or systemic illness (intravenous): ceftriaxone 2 g once daily with metronidazole 500 mg every 8 hours, or piperacillin-tazobactam 4.5 g every 8 hours. Add clindamycin 600 mg every 8 hours if necrotising infection or toxin-producing streptococcal infection is suspected.
• Paracetamol 1 g every 6 hours for pain (maximum 4 g in 24 hours). Lactulose 15 mL twice daily to soften stool.
• Procedures: drainage of abscess or collection, debridement of necrotic tissue, and removal of infected sutures. Secondary resuturing is considered after infection has cleared and tissue is healthy (usually at least 6 weeks).
• Necrotising fasciitis: urgent radical debridement and critical care.
• Special groups: diabetic women need glucose control. Women with fourth degree tears need combined review of the sphincter and bowel function.
• Red flags: rapidly spreading erythema, severe pain, crepitus, systemic sepsis, offensive discharge with tissue necrosis, and wound breakdown over a repaired sphincter.
• Follow-up: wound review within 48 to 72 hours. Review at 6 weeks to assess healing, dyspareunia and continence.