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.
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:
- 1. Abuhamad A, Chaoui R. A Practical Guide to Fetal Echocardiography, Normal and Abnormal Hearts. Lippincott Williams & Wilkins. (2009) ISBN:0781797578. Read it at Google Books - Find it at Amazon
- 2. Traisrisilp K, Tongprasert F, Srisupundit K et-al. Reference ranges for the fetal cardiac circumference derived by cardio-spatiotemporal image correlation from 14 to 40 weeks' gestation. J Ultrasound Med. 2011;30 (9): 1191-6. J Ultrasound Med (full text) - Pubmed citation