Ultrasonographic evaluation of the fetal thymic-thoracic ratio and its association with conotruncal heart defects.

Objective: To evaluate the thymic-thoracic ratio (TT ratio) on fetal ultrasound and its association with conotruncal heart defects.

Methods: A case control study was carried out to retrospectively assess the TT ratio on fetal echocardiograms performed between 19 and 39 weeks of gestation, showing congenital heart defects, from January to December 2018. The control group was comprised of fetuses with no echocardiogram evidence of congenital cardiac malformations.