What are the Royal College of Obstetricians and Gynaecologists (RCOG) guidelines for interpreting and managing cardiotocography (CTG) traces?

RCOG CTG Guidelines

I must note that the evidence provided does not contain actual RCOG (Royal College of Obstetricians and Gynaecologists) guidelines - instead, it primarily references American guidelines (NICHD/ACOG) from 2009. However, I can provide guidance based on the available evidence that references RCOG classification systems.

CTG Classification System

CTG traces should be classified into three categories: Normal, Suspicious (Abnormal), and Pathological, with management escalating based on category 1. This three-tier system aligns with both RCOG and NICHD frameworks referenced in the evidence.

Category I (Normal)

• Normal baseline FHR (110-160 bpm)
• Moderate baseline variability present
• No late or variable decelerations
• Accelerations may be present or absent
• Management: Continue current monitoring 2

Category II (Suspicious/Indeterminate)

Features include any of the following:

• Baseline FHR changes (bradycardia <110 bpm without absent variability, or tachycardia)
• Minimal or absent baseline variability
• Absence of accelerations
• Recurrent variable decelerations with moderate variability
• Prolonged decelerations (>2 minutes but <10 minutes)

Management approach:

1. Consider discontinuing oxytocin
2. Implement conservative measures (detailed below)
3. Assess need for expedited delivery if abnormalities persist or worsen 2

Category III (Pathological)

Absent baseline FHR variability with any of:

• Recurrent late decelerations
• Recurrent variable decelerations
• Bradycardia
• OR sinusoidal pattern

Management: Discontinue oxytocin immediately and expedite delivery (operative vaginal or cesarean) 2

Understanding Deceleration Patterns

Early Decelerations

• Mirror uterine contractions symmetrically
• Nadir coincides with contraction peak
• Rarely go below 100 bpm
• Nearly always benign - no intervention needed 2

Variable Decelerations

• Usually benign, related to cord compression
• Common in second stage of labor
• Atypical features suggest hypoxemia:
  • Late onset relative to contractions
  • Loss of shoulders
  • Slow recovery 2

Late Decelerations

• Onset after contraction begins
• Nadir occurs after contraction peak
• Indicates uteroplacental insufficiency
• May be subtle - use straight edge along baseline to detect 2
• Always pathological and require intervention

Prolonged Decelerations

• Duration: 2-10 minutes
• Causes: head compression, cord compression, or uteroplacental insufficiency
• Management depends on clinical context and other FHR features 2

Intrauterine Resuscitation Protocol

When CTG becomes suspicious or pathological, implement these interventions systematically:

1. Change maternal position (left lateral preferred)
2. Assess maternal vital signs (temperature, BP, pulse)
3. Discontinue oxytocin infusion if running
4. Initiate oxygen at 6-10 L/minute
5. Perform vaginal examination - check for:
   • Cord prolapse
   • Rapid fetal descent
   • Vaginal bleeding (abruption)
6. Give IV fluid bolus if not already administered
7. Assess fetal pH via:
   • Fetal scalp stimulation
   • Acoustic stimulation
   • (Scalp pH sampling rarely used now)
8. Consider amnioinfusion for recurrent moderate-severe variable decelerations
9. Expedite delivery if abnormalities persist 2

Fetal Scalp Stimulation

If absent or minimal variability without spontaneous accelerations:

• Perform scalp or acoustic stimulation
• Presence of acceleration indicates fetal pH ≥7.20 2
• Absence of acceleration warrants consideration for expedited delivery

Critical Pitfalls

High interobserver variability exists, particularly for:

• Baseline variability assessment
• Deceleration classification
• Overall trace categorization 3

CTG has low positive predictive value:

• Sensitivity for pH <7.20: only 42.9%
• Specificity: 73.6%
• Many "pathological" traces do not have actual acidemia 4

Therefore: Never rely on CTG in isolation - integrate with:

• Maternal risk factors (pregestational diabetes, preeclampsia strongly associated with acidemia 4)
• Clinical context
• Stage of labor (severe decelerations less significant if delivery imminent 2)

Documentation Requirements

• Regular review by physicians and nurses throughout labor
• Ensure good quality tracing
• Document all interventions and timing
• Consider flow sheets/partograms
• Obtain cord blood gases after any delivery with abnormal FHR tracing (pH <7.00 or base deficit >12 mmol/L indicates acute hypoxic event) 2

Amnioinfusion Benefits

For recurrent deep variable decelerations, amnioinfusion reduces:

• Frequency of decelerations
• Cesarean delivery rates
• Apgar scores <7 at 5 minutes
• Low cord arterial pH (<7.20)
• Maternal and neonatal hospital stays >3 days 2