Cardiotocography (CTG) Overview

Cardiotocography (CTG)

• CTG is most commonly used in the third trimester.
• CTG monitors fetal well-being and detects fetal distress.
• The purpose of CTG is to monitor the fetal heart rate and uterine contractions.

How CTG Works

• Two transducers are used, one to monitor fetal heart rate via ultrasound and the other to monitor uterine contractions.

How to Read a CTG

• FHR: Baseline rate, variability, accelerations, decelerations.
• C: Contractions — frequency, duration, intensity, regularity.
• O: Overall impression.

Fetal Heart Rate (FHR)

• The baseline rate is the average heart rate within a 10-minute window, excluding accelerations and decelerations.
• A normal fetal heart rate is 110-160 bpm.

Variability

• Baseline variability refers to the variation in fetal heart rate between beats.
• Normal variability is 5-25 bpm.

Variability Categories

• Reassuring: 5-25 bpm.
• Non-reassuring: Less than 5 bpm for 30-50 minutes or more than 25 bpm for 15-25 minutes.
• Abnormal: Less than 5 bpm for more than 50 minutes or more than 25 bpm for more than 25 minutes.

Accelerations

• An abrupt increase of greater than 15 bpm in the baseline fetal heart rate for more than 15 seconds is considered reassuring.

Decelerations

• Decelerations are categorized into early, late, and variable decelerations.
• They are abrupt decreases in the baseline fetal heart rate of > 15 bpm for > 15 seconds.

Early Decelerations

• Occur during uterine contractions.
• Recover when contractions end.
• Physiologic (not pathological).
• Due to increased fetal intracranial pressure.

Late Decelerations

• Occur after contractions begin.
• Recover after contractions end.
• Pathological/abnormal.
• Due to insufficient blood flow to the uterus and placenta (e.g., maternal hypotension or placental abruption).
• Leads to fetal hypoxia and acidosis.

Variable Decelerations

• Can occur at any time during a contraction cycle.
• May or may not correlate with a contraction.
• Usually caused by umbilical cord compression.

Contractions (C)

• Record the number of contractions in a 10-minute period.
• Observe individual contractions as peaks.
• Analyze the following:
  • Frequency: Number of contractions in 10 minutes.
  • Duration: Beginning to end of a single contraction.
  • Intensity: Strength of contractions (assessed by palpation).
  • Regularity: Intervals of time between contractions.

Types of Contractions

• Mild: <40 mmHg
• Moderate: 40-80 mmHg
• Severe: 80-100 mmHg

Overall Impression

• Assess all aspects of the CTG, describe impression as either reassurin,suspicious or abnormal.

This quiz explores the essential concepts of cardiotocography (CTG), focusing on its use in monitoring fetal well-being during the third trimester. Learn how to read CTG data including fetal heart rate (FHR), variability, and uterine contractions. Test your understanding of CTG's importance in detecting fetal distress and overall assessment.