Fetal cardiothoracic circumference ratio

Dr Dan J Bell and Radswiki et al.

Fetal cardiothoracic (C/T) circumference ratio is a parameter than can be used in assessment of fetal cardiac and thoracic/chest wall anomalies. It is the ratio of the cardiac circumference to the thoracic circumference and may be easily measured on fetal ultrasound/echocardiography. 

Radiographic features


The C/T circumference ratio should be always <0.5 throughout gestation. It slowly increases throughout gestation:

  • ~11 weeks: 0.38
  • ~17-20 weeks: 0.45
  • term: 0.5

Increased C/T circumference ratios can be observed with either cardiac or thoracic pathology:

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Article information

rID: 15006
Sections: Approach, Signs
Tag: cases
Synonyms or Alternate Spellings:
  • Fetal cardio thoracic (C-T) circumference ratio
  • Fetal cardio-thoracic circumference ratio
  • Fetal CT circumference ratio

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