Chorioamnionitis

Chorioamnionitis (intra amniotic infection, now termed "triple I": intrauterine inflammation or infection or both) is infection and inflammation of the chorion, amnion, amniotic fluid, placenta and sometimes fetus, complicating about 1 to 4% of term and up to 40 to 70% of very preterm deliveries (below 28 weeks).

The infection usually ascends from the lower genital tract (E. coli, group B streptococcus, Ureaplasma, Mycoplasma hominis, Gardnerella, anaerobes, Fusobacterium), and less often is haematogenous (Listeria) or iatrogenic (amniocentesis).

Risk factors: prolonged rupture of membranes (above 18 hours), prolonged labour, multiple vaginal examinations, nulliparity, internal fetal monitoring, bacterial vaginosis, GBS colonisation, meconium stained fluid, smoking, and cervical insufficiency.

Maternal complications: sepsis, uterine atony and postpartum haemorrhage, caesarean section (increased dysfunctional labour), endometritis, wound infection, pelvic abscess and thrombophlebitis. Fetal and neonatal complications: sepsis, pneumonia, meningitis, cerebral palsy, bronchopulmonary dysplasia and death.

• Maternal fever of 38.0 degrees C or above (the principal criterion), with maternal tachycardia (above 100/min), fetal tachycardia (above 160/min for 10 minutes or more), uterine tenderness, malodorous or purulent vaginal discharge or amniotic fluid, and maternal leucocytosis (above 15,000/microlitre without steroids)
• Preterm labour or PPROM presenting with these signs
• Triple I classification: isolated maternal fever (single oral temperature of 39.0 degrees C or above, or 38.0 to 38.9 degrees C persisting for 30 minutes), suspected (fever with one or more of: baseline fetal tachycardia, maternal leucocytosis, purulent cervical drainage), and confirmed (amniocentesis proving infection, or placental histopathology)

• Clinical diagnosis based on fever and associated features; exclude other sources (epidural related fever, urinary tract infection, respiratory infection, appendicitis, influenza)
• Laboratory: full blood count, C-reactive protein, blood cultures, urinalysis, and high vaginal and cervical swabs (GBS, chlamydia, gonorrhoea)
• Amniocentesis when diagnosis is uncertain in preterm gestations: glucose below 14 mg/dL, Gram stain positive, white cell count above 30 cells/mm3, culture positive, interleukin-6 above 2.6 ng/mL
• Cardiotocography showing fetal tachycardia and reduced variability
• Placental histology (acute chorioamnionitis, funisitis)

• Antibiotics started immediately at diagnosis (do not wait for delivery): ampicillin 2 g IV every 6 hours plus gentamicin 5 mg/kg IV once daily (or 1.5 mg/kg every 8 hours); for penicillin allergic patients cefazolin 2 g every 8 hours (non-anaphylactic reactions) or clindamycin 900 mg every 8 hours with gentamicin; add clindamycin 900 mg IV every 8 hours or metronidazole 500 mg IV every 8 hours after caesarean delivery to cover anaerobes; for severe or resistant infection use piperacillin tazobactam 4.5 g IV every 6 hours or meropenem 1 g every 8 hours.
• Antipyretics: paracetamol 1 g orally every 6 hours.
• Delivery: induction or augmentation of labour with oxytocin; chorioamnionitis alone is not an indication for caesarean section, which is reserved for obstetric indications. Expedite delivery regardless of gestational age. Fluid resuscitation and monitoring for maternal sepsis.
• Postpartum antibiotics: after vaginal delivery, no additional dose or a single further dose is usually sufficient; after caesarean, continue until the patient is afebrile for 24 to 48 hours (typically 24 hours of clinical improvement).
• Uterotonic readiness: oxytocin and carboprost for atony; monitor for postpartum haemorrhage.
• Neonatal: notify neonatal team; the infant needs sepsis evaluation and empirical antibiotics (ampicillin and gentamicin), according to local early onset sepsis protocols.
• Prevention: GBS screening and intrapartum prophylaxis (benzylpenicillin 5 million units IV then 2.5 to 3 million units every 4 hours), minimise vaginal examinations, and time limited induction.