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Cardiotocography (CTG)

Extracted from Survival Guide to Midwifery, 2nd Edition (2012) Diane M. Fraser and Margaret A. Cooper, Oxford; Churchill Livingstone: 2012. Courtesy Elsevier

Measurement of the fetal heart rate and uterine contractions. The aim of cardiotocography (CTG) is to identify changes to the fetal heart rate that may be indicative of a developing fetal compromise.

 

 

 

Normal CTG showing baseline variability

The CTG provides information on:

  • Baseline fetal heart rate
  • Baseline variability
  • Accelerations from base rate
  • Decelerations from base rate
  • Uterine activity 
  •  
CTG classification
Normal A CTG where all four features fall into the reassuring category
Suspicious A CTG where features fall into one of the non-reassuring categories and the remaining features are reassuring
Pathological A CTG where features fall into two or more non-reassuring categories or one or more abnormal categories
Fetal heart rate features classification
  Baseline (bpm) Variability (bpm) Decelerations Accelerations
Reassuring 110 - 160 ≥5 None Present
Non-reassuring 100 - 109
161 - 180
≥5 for ≥40 but <90 minutes Early decelerations Variable decelerations Single prolonged deceleration up to 3 minutes The absence of accelerations with an otherwise normal CTG is of uncertain significance
Abnormal <100 >180 Sinusoidal pattern for ≥10 minutes <5 for ≥90 minutes Atypical variable decelerations Late decelerations Single prolonged deceleration up to 3 minutes

Women with a low risk pregnancy should have intermittent auscultation with a Pinard stethoscope or hand-held Doppler device. There is no evidence to support CTG on admission. However, for women with a higher risk pregnancy, electronic fetal monitoring is appropriate. The use of CTG may limit the choice of position for the woman in labour.

The Practising Midwife featured articles

Use of technology in childbirth: 4. Electronic fetal monitoring Author: Alison Brodrick 2012; 15 (1): 39-43

Cochrane Corner: Cardiotocography vs intermittent auscultation 2012; 15(3): 34-35 Author: Declan Devane

Further reading

National Institute for Health and Care Excellence CG190 (2014). Intrapartum care for healthy women and babies. Available at: https://www.nice.org.uk/guidance/cg190

Royal College of Midwives (2012) Evidence Based Guidelines for Midwifery-Led Care in Labour. Intermittent Auscultation. Available at: https://www.rcm.org.uk/sites/default/files/Intermittent%20Auscultation%20(IA)_0.pdf

NHS Litigation Authority (2010) Maternity Claims - Information Sheet 7. CTG Interpretation. Available at: http://www.nhsla.com/safety/Documents/CTG%20Interpretation%20-%207.pdf

 

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