What is the management approach for category 2 Cardiotocography (CTG) in relation to fetal well-being and neonatal outcomes?

Management of Category 2 Cardiotocography (CTG) and Its Relationship to Neonatal Outcomes

Category 2 CTG patterns require increased monitoring frequency and specific interventions to improve fetal outcomes, with management decisions based on the severity of abnormalities and associated risk factors.

Understanding Category 2 CTG

• Category 2 CTG patterns are considered "indeterminate" and represent more than 50% of fetal monitoring strips that fall between normal and abnormal tracings 1
• These patterns are concerning enough to warrant increased surveillance and interventions but do not necessarily require immediate delivery 1
• Category 2 patterns include baseline FHR changes, minimal or absent variability, absence of accelerations, and periodic or episodic decelerations 1

Immediate Management of Category 2 CTG

• Consider discontinuing oxytocin if being administered 1
• Implement general measures including vaginal examination, checking maternal vital signs, administering oxygen, changing maternal position, and providing intravenous fluids 1
• Assess fetal pH with acoustic or fetal scalp stimulation to further evaluate fetal status 1
• Consider potential need to expedite delivery if abnormalities persist or worsen 1

Monitoring Frequency Based on CTG Category

• For Category 2 CTG without absent/reversed end-diastolic velocity, weekly cardiotocography testing is recommended after viability 2
• Increase frequency to twice weekly or more when Category 2 patterns are accompanied by other risk factors such as fetal growth restriction 2, 3
• For high-risk pregnancies with normal umbilical artery Doppler, CTG monitoring is recommended every 2 weeks 3
• For high-risk pregnancies with abnormal umbilical artery Doppler, CTG monitoring should be performed at least weekly 3

Integration with Doppler Studies

• Serial umbilical artery Doppler assessment should be performed to assess for deterioration once fetal growth restriction is diagnosed 2
• With decreased end-diastolic velocity or severe fetal growth restriction (estimated fetal weight less than the third percentile), weekly umbilical artery Doppler evaluation is suggested 1
• Doppler assessment should be increased to 2-3 times per week when umbilical artery absent end-diastolic velocity is detected 1
• In the setting of reversed end-diastolic velocity, heightened surveillance with cardiotocography at least 1-2 times per day is recommended 1

Timing of Delivery Based on CTG and Doppler Findings

• For fetal growth restriction with normal umbilical artery Doppler and estimated fetal weight between 3rd-10th percentile: Delivery at 38-39 weeks 1, 3
• For fetal growth restriction with decreased diastolic flow but without absent/reversed end-diastolic velocity or with severe fetal growth restriction: Delivery at 37 weeks 1, 3
• For fetal growth restriction with absent end-diastolic velocity: Delivery at 33-34 weeks 1, 3
• For fetal growth restriction with reversed end-diastolic velocity: Delivery at 30-32 weeks 1, 3

Mode of Delivery Considerations

• If umbilical artery end-diastolic flow is present, induction of labor with continuous CTG monitoring is recommended 1
• For pregnancies with fetal growth restriction complicated by absent/reversed end-diastolic velocity, cesarean delivery should be considered based on the entire clinical scenario 1, 3

Relationship to Neonatal Outcomes

• Continuous CTG monitoring is associated with reduced rates of neonatal seizures but no clear differences in cerebral palsy or infant mortality 4
• Infants born with severe compromise often show specific abnormalities in their first-hour CTG, including baseline fetal heart rate ≥150 bpm, non-reactive trace, reduced variability, and absence of accelerations 5
• The positive predictive value of CTG for intrapartum fetal hypoxia is approximately only 30%, with a high false-positive rate of 60% 6
• Despite widespread use, there is limited evidence that antenatal testing decreases the risk for fetal death in low-risk pregnancies 3

Common Pitfalls to Avoid

• Relying solely on CTG for surveillance without integrating Doppler studies 2
• Using CTG as the only form of surveillance in high-risk pregnancies 2
• Failing to increase monitoring frequency when deterioration in Doppler parameters is observed 2
• Delaying delivery when significant abnormalities are detected on CTG in the context of fetal growth restriction 2
• Interpreting CTG based solely on pattern recognition without understanding the underlying physiology of fetal heart rate changes 6

Special Considerations for Preterm Fetuses

• Physiological control of fetal heart rate and the resultant features observed on the CTG trace differs in the preterm fetus compared to a fetus at term, making interpretation more challenging 7
• Antenatal corticosteroids are recommended if delivery is anticipated before 33 6/7 weeks of gestation 1
• Intrapartum magnesium sulfate is recommended for fetal and neonatal neuroprotection for women with pregnancies that are <32 weeks of gestation 1