Cardiothoracic ratio in the first half of pregnancy

Abstract

Calculation of the C/T ratio is a simple, reliable, reproducible, and time-efficient means of assessing the size of the fetal heart. By comparing the C/T ratio with the normal values presented here, physicians should be able to more easily identify cases of cardiomegaly early in their patients' pregnancies.

Reference values for variables of fetal cardiocirculatory dynamics at 11–14 weeks of gestation

“…We found this ratio to be less than that reported in the second trimester, but similar to what has been reported during the late first trimester25. Although our values differ slightly from some in previously published reports26, the discrepancy may be related to methodological differences, e.g. measuring the thorax along the skin edge rather than the rib or using the ellipse rather than the diameter method to derive the circumference27.…”

Fetal cardiac dimensions at 14–40 weeks' gestation obtained using cardio‐STIC‐M

“…Several techniques for assessing cardiac dimensions have been published20, 21. 2D ultrasound is prone to providing an incorrect plane of the exact four‐chamber view, even if the ultrasound beam is precisely perpendicular to the IVS, since it can be tilted towards or away from the examiner on the z‐axis, resulting in asymmetry of left‐ and right‐sidedness of the heart, and leading to inaccurate measurement of cardiac dimensions.…”

Sonographic Markers of Fetal α‐Thalassemia Major

“…35,36 Because specific anatomic landmarks are available during cardiothoracic ratio measurement, its repeatability is better than that of other sonographic markers. In addition, since the cardiothoracic ratio is a relatively stable index during pregnancy, rising from 0.38 to 0.45 at 11 to 20 weeks, 37 cardiothoracic ratio cutoff values ranging from 0.50 at 12 weeks to 0.53 at 21 weeks have been used (Table 1). 29,30,[38][39][40] Considering that the heart is very small in early pregnancy, and it is hard to outline the border, many authors advocated transvaginal scanning when adequate images could not be obtained transabdominally at an early gestational age (GA).…”