When does the American College of Obstetricians and Gynecologists (ACOG) recommend obtaining cord gases?

ACOG Recommendations for Obtaining Cord Gases

According to ACOG guidelines, umbilical cord blood gas and acid-base analysis should be obtained when there is a low 5-minute Apgar score (≤5), cesarean delivery for fetal compromise, severe growth restriction, abnormal fetal heart rate tracing, maternal thyroid disease, intrapartum fever, or multifetal gestation. 1

Specific Indications for Cord Gas Collection

Primary Indications

• 5-minute Apgar score of 5 or less 2
• Cesarean delivery performed for fetal compromise
• Severe intrauterine growth restriction
• Abnormal fetal heart rate tracing
• Maternal thyroid disease
• Intrapartum fever
• Multiple gestation

Additional Indications Based on Fetal Monitoring

• Category III fetal heart rate patterns (absent variability with recurrent decelerations, bradycardia, or sinusoidal pattern) 2
• Persistent category II patterns that fail to respond to intrauterine resuscitation measures

Importance of Cord Gas Analysis

Umbilical cord blood gas analysis provides the most objective determination of fetal metabolic condition at birth. This information is particularly valuable for:

1. Diagnosing intrapartum hypoxic events: Cord pH less than 7.00 or base deficit greater than 12 mmol/L is one of the four essential criteria for determining an acute intrapartum hypoxic event sufficient to cause cerebral palsy 2

2. Risk stratification: Moderate and severe newborn complications increase significantly with:

   • Umbilical arterial base deficit of 12-16 mmol/L (10% complication rate)
   • Umbilical arterial base deficit greater than 16 mmol/L (40% complication rate) 1

3. Medicolegal documentation: Provides objective evidence of neonatal status at birth, particularly important when abnormal fetal heart rate patterns were present

Proper Collection Technique

• Immediately after delivery, a segment of umbilical cord should be double-clamped and divided
• Both arterial and venous samples should be obtained when possible
• Samples should be collected before placental separation when feasible

Clinical Significance of Abnormal Results

Neonates with acidemia (pH ≤7.0) despite normal 5-minute Apgar scores (≥7) have increased risks of:

• Respiratory distress syndrome (adjusted OR 6.5)
• NICU admission (adjusted OR 10.8)
• Neonatal sepsis (when base excess ≤-12 mmol/L, adjusted OR 4.7) 3

Common Pitfalls to Avoid

1. Relying solely on Apgar scores: Up to 17.8% of preterm infants with 5-minute Apgar scores <7 can have acidemia (arterial pH ≤7.10) 4

2. Failing to collect samples in high-risk deliveries: Studies show inconsistent compliance with collection recommendations, with only 52% of births with low Apgar scores having cord gases measured 5

3. Misinterpreting normal values in preterm infants: Mean arterial pH in preterm infants is 7.26 ± 0.08, which is similar to term infants 4

4. Neglecting placental pathology: When a neonate has a low Apgar score, both cord gases and placental histology should be obtained to help determine causation 5

By following these ACOG recommendations for cord gas collection, clinicians can better assess neonatal risk, guide immediate management decisions, and provide valuable documentation for both clinical care and potential medicolegal situations.