What are the latest guidelines for Cardiotocography (CTG) monitoring?

Latest Guidelines for Cardiotocography (CTG) Monitoring

Cardiotocography (CTG) monitoring should be performed weekly after viability for fetal growth restriction (FGR) without absent/reversed end-diastolic velocity (AEDV/REDV) in the umbilical artery, with increased frequency when FGR is complicated by AEDV/REDV or other comorbidities. 1

Key Parameters for CTG Interpretation

• Normal fetal heart rate baseline ranges between 110-160 beats per minute 2
• Accelerations (transitory increases in fetal heart rate of at least 15 beats per minute lasting 15 seconds or more) are considered reassuring signs of fetal well-being 2
• Early decelerations (gradual decreases in fetal heart rate that coincide with contractions) are generally benign 2

CTG Monitoring in Fetal Growth Restriction

Frequency of Monitoring

• Weekly CTG testing is recommended after viability for FGR without AEDV/REDV 1
• Increase frequency to twice weekly or more when FGR is complicated by AEDV/REDV or other comorbidities 1
• CTG should not be used as the only form of surveillance in FGR 1

Timing Based on Umbilical Artery Doppler Findings

• With normal umbilical artery Doppler: CTG monitoring every 2 weeks 1
• With abnormal umbilical artery Doppler (elevated PI but present end-diastolic flow): CTG monitoring at least weekly 1
• With absent end-diastolic velocity (AEDV): CTG monitoring 1-2 times per day, with consideration for hospitalization and administration of antenatal corticosteroids 1
• With reversed end-diastolic velocity (REDV): CTG monitoring 1-2 times per day, with hospitalization and consideration for delivery 1

Integration with Other Monitoring Modalities

• CTG should be used in conjunction with umbilical artery Doppler assessment in FGR 1
• Serial umbilical artery Doppler assessment should be performed to assess for deterioration once FGR is diagnosed 1
• In the setting of REDV, hospitalization, antenatal corticosteroids, and heightened surveillance with CTG at least 1-2 times per day is suggested 1

Delivery Timing Based on CTG and Doppler Findings

• For FGR with normal umbilical artery Doppler and estimated fetal weight (EFW) between 3rd-10th percentile: Delivery at 38-39 weeks 1
• For FGR with decreased diastolic flow (but without AEDV/REDV) or severe FGR with EFW less than 3rd percentile: Delivery at 37 weeks 1
• For FGR with AEDV: Delivery at 33-34 weeks 1
• For FGR with REDV: Delivery at 30-32 weeks 1

Mode of Delivery Considerations

• For pregnancies with FGR complicated by AEDV/REDV, cesarean delivery should be considered based on the entire clinical scenario 1
• If umbilical end-diastolic flow is present, induction of labor with continuous CTG monitoring is recommended 1
• FGR alone is not an indication for cesarean section, but cesarean delivery should be considered for very preterm FGR or severe umbilical artery Doppler abnormalities 1

Common Pitfalls to Avoid

• Relying solely on CTG for surveillance without integrating Doppler studies 1
• Using CTG as the only form of surveillance in high-risk pregnancies 1
• Failing to increase monitoring frequency when deterioration in Doppler parameters is observed 1
• Delaying delivery when significant abnormalities are detected on CTG in the context of FGR 1

Technical Considerations

• External monitoring using ultrasound transducer for FHR and tocodynamometer for uterine contractions is recommended for routine clinical use in both antepartum and intrapartum periods 3
• Internal monitoring (fetal electrode and intrauterine pressure sensors) provides more precise signals but is only applicable during labor after cervical dilation and membrane rupture 3
• Visual analysis of CTG has poor reproducibility due to the complexity of physiological phenomena affecting fetal heart rhythm 4

Despite widespread use of CTG monitoring, its clinical utility is limited by relatively poor positive predictive value and significant inter- and intra-observer variability in interpretation 5, 6. Understanding the physiology behind fetal heart rate changes rather than purely relying on pattern recognition is essential for appropriate clinical management 6.