Postpartum Wound Infection

Postpartum wound infection is infection of a wound made by birth, which includes a caesarean incision, an episiotomy, a perineal tear repair and a drain site, in the 6 weeks after delivery. Staphylococcus aureus, streptococci, Escherichia coli and anaerobes are common. It affects 3 to 15 percent of caesarean wounds and 0.1 to 3 percent of perineal wounds, and it matters because it delays healing and may spread deeply.

• Risk factors: obesity, diabetes, emergency surgery, long labour, rupture of membranes for 18 hours or more, chorioamnionitis, anaemia, HIV, smoking, poor hygiene, lack of antibiotic cover at surgery.
• Usually appears 3 to 10 days after birth.
• Deep or necrotising infection is an emergency.

Women have wound pain that worsens, redness, swelling, warmth, pus and fever. Deeper infection causes hard swelling, spreading redness and severe pain.

• Redness spreading beyond the wound edge.
• Pus or foul discharge, wound gaping.
• Differential diagnosis: wound haematoma, seroma, normal wound inflammation, endometritis, stitch reaction, cellulitis from another source, necrotising fasciitis, abscess.
• Complications: wound breakdown, abscess, necrotising fasciitis, sepsis, fistula, incisional hernia, anal sphincter or perineal body damage, prolonged healing.

The approach is wound examination and culture.

• Inspect the wound and mark the edge of redness; palpate for induration and fluctuance; probe gently for depth.
• Temperature, pulse, blood pressure; swab or aspirate pus for Gram stain and culture; full blood count, C-reactive protein, glucose, blood culture if febrile.
• Ultrasound for collection; CT if necrotising infection is suspected.
• Check the uterus and breasts for other sources of fever.

The principle is to open and drain pus, clean the wound, and give antibiotics when infection is spreading.

• Supportive: remove sutures from the infected part and open the wound; irrigate with sodium chloride 0.9 percent; pack loosely with moist gauze once or twice daily; keep dry; sitz baths twice daily for perineal wounds; glucose control with insulin to keep glucose below 10 mmol/L; nutrition and fluids; breastfeeding continues.
• Pharmacological: mild infection: flucloxacillin 500 mg oral 6-hourly for 7 days, or amoxicillin-clavulanate 625 mg oral 8-hourly for 7 days; moderate or 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; suspected methicillin-resistant Staphylococcus aureus: clindamycin 450 mg oral 8-hourly or vancomycin 15 mg/kg IV 12-hourly; necrotising infection: meropenem 1 g IV 8-hourly plus clindamycin 900 mg IV 8-hourly plus vancomycin 15 mg/kg IV 12-hourly; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours).
• Procedures: bedside opening and drainage; surgical debridement of dead tissue; urgent wide debridement for necrotising fasciitis; delayed secondary closure or negative pressure dressing after 5 to 7 days when the wound is clean.
• Special groups: diabetic women need insulin to keep glucose below 10 mmol/L and a 10 to 14 day antibiotic course.
• Red flags: rapidly spreading redness, blistering or dusky skin, pain out of proportion, crepitus, fever above 39 degrees Celsius, hypotension, confusion.
• Follow-up: wound review every 2 days until healing; review at 1 week and 6 weeks; advise on wound hygiene and avoiding heavy lifting for 6 weeks.