What are the clinical criteria for diagnosing chorioamnionitis during labor?

Clinical Criteria for Chorioamnionitis

Diagnostic Criteria

Chorioamnionitis is diagnosed clinically based on maternal fever (≥100.4°F/38.0°C) plus at least one additional sign: maternal tachycardia, fetal tachycardia, uterine tenderness, foul-smelling amniotic fluid, or maternal leukocytosis. 1

The Centers for Disease Control and Prevention specifies that the diagnosis requires:

• Maternal fever ≥100.4°F (38.0°C) as the mandatory criterion 1
• Plus one or more of the following:
  • Maternal tachycardia 1
  • Fetal tachycardia 1
  • Uterine tenderness 1
  • Foul-smelling or purulent amniotic fluid 1
  • Maternal leukocytosis 1

Critical Management Principles

Do not wait for maternal fever to develop before initiating treatment—the condition can present without fever, especially at earlier gestational ages, and treatment should begin as soon as any other sign of infection appears. 1

Maternal sepsis can progress rapidly with a median interval from first infection signs to death of only 18 hours, making immediate treatment essential. 1

Broad-spectrum intravenous antibiotics (ampicillin plus gentamicin) must be administered promptly after clinical diagnosis, and delivery should be undertaken without delay once antibiotics are started. 1

Important Diagnostic Limitations

The clinical criteria have significant limitations that clinicians must understand:

• The accuracy of each individual clinical sign for identifying true intra-amniotic infection ranges only between 46.7% and 57.8%. 2
• Only approximately 60% of patients diagnosed with clinical chorioamnionitis actually have proven intra-amniotic infection when amniotic fluid is analyzed using culture or molecular techniques. 3, 4
• The combination of fever with three or more clinical criteria does not substantially improve diagnostic accuracy. 2

Common Pitfalls

Epidural analgesia can cause fever, potentially leading to overdiagnosis—however, when clinical suspicion exists, err on the side of treatment rather than observation. 5

Consultation with obstetric providers is important to determine the level of clinical suspicion, as chorioamnionitis signs can be nonspecific. 6

Amniocentesis results must not delay initiation of therapy; clinical management should proceed based on bedside assessment. 1

Neonatal Management Implications

The diagnosis of maternal chorioamnionitis triggers specific neonatal protocols:

Well-Appearing Newborns

• Obtain limited evaluation: blood culture and CBC with differential (at birth and/or at 6-12 hours of life). 6, 1
• Begin empirical antibiotics: IV ampicillin for GBS coverage plus an agent active against E. coli. 1
• Observe for ≥48 hours. 6

Newborns with Signs of Sepsis

• Perform full diagnostic evaluation: blood culture, CBC with differential and platelets, chest radiograph if respiratory abnormalities present, and lumbar puncture if patient is stable. 6, 1
• Initiate empirical broad-spectrum antibiotics immediately, directed toward the most common causes of neonatal sepsis. 6

Delivery Considerations

The route of delivery is dictated by standard obstetric indications—not by the infection itself; cesarean delivery offers no fetal advantage and may increase maternal morbidity. 1

Chorioamnionitis cannot be cured by antibiotics alone; delivery must proceed without delay once treatment is initiated. 1