Postpartum Perineal Infection

Postpartum perineal infection is infection of the perineal skin, muscle or deeper tissue after a tear or after repair, either spontaneous or surgical, in the weeks after birth. It occurs in 0.1 to 3 percent of vaginal births and is more common after third and fourth degree tears, instrumental delivery and prolonged labour. It matters because deep infection destroys the repair, can reach the anal sphincter, and may progress to necrotising infection.

• Risk factors: third or fourth degree tear, forceps, prolonged second stage, macrosomia, obesity, diabetes, anaemia, haematoma, poor hygiene, tight sutures.
• Typically appears on days 2 to 7.
• Early antibiotics lower the risk of breakdown.

Women have perineal pain that increases after day 2, swelling, redness, a foul discharge, fever and pain on passing urine or stool. The wound is tender, hot and may be gaping with pus.

• Throbbing pain, difficulty sitting.
• Foul smelling discharge and fever.
• Differential diagnosis: perineal haematoma, normal wound pain, urinary tract infection, retained gauze or swab, endometritis, perineal abscess, necrotising fasciitis.
• Complications: wound breakdown, abscess, necrotising fasciitis, sepsis, rectovaginal fistula, anal sphincter injury, chronic perineal pain, dyspareunia.

The approach is careful examination of the perineum, with a rectal examination.

• Inspect with good light and an assistant; note colour, swelling, gaping, pus and necrosis; gentle digital examination of the vagina and rectum for sphincter integrity and retained swab.
• Temperature, pulse, blood pressure; wound swab for culture; full blood count, C-reactive protein, glucose.
• Ultrasound or endo-anal ultrasound (where available) for collection or sphincter defect; CT for suspected necrotising infection.
• Urine dipstick and culture.

The principle is to drain pus, clean the wound, give antibiotics and delay re-suturing until it is clean.

• Supportive: remove infected sutures and open the wound; irrigate with sodium chloride 0.9 percent twice daily; sitz baths with warm water 3 times daily; keep dry; ice for pain in the first 24 hours; lactulose to soften stool; hygiene advice; breastfeeding continues.
• Pharmacological: amoxicillin-clavulanate 625 mg oral 8-hourly for 7 days; severe infection: ceftriaxone 2 g IV once daily plus metronidazole 500 mg IV 8-hourly until afebrile for 48 hours, then amoxicillin-clavulanate 625 mg oral 8-hourly to complete 7 days; necrotising infection: meropenem 1 g IV 8-hourly plus clindamycin 900 mg IV 8-hourly plus vancomycin 15 mg/kg IV 12-hourly; lactulose 15 mL oral 12-hourly; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours); diclofenac 50 mg oral 8-hourly for 3 days with food if no contraindication.
• Procedures: drainage of abscess; surgical debridement; urgent wide debridement for necrotising infection; secondary repair after 2 to 6 weeks when the wound is clean and granulating; sphincter repair after 3 months if the sphincter is disrupted.
• Special groups: diabetic women need insulin to keep glucose below 10 mmol/L.
• Red flags: dusky skin, crepitus, severe pain out of proportion, fever above 39 degrees Celsius, hypotension, leaking stool or flatus from the vagina, rapidly spreading swelling.
• Follow-up: wound review every 2 to 3 days; review at 1 week and 6 weeks; pelvic floor and anal function assessment at 6 weeks; counselling on the next birth.