Thymus size at birth in echocardiography: a cohort study

Abstract Background Echocardiography is a tool used in neonatal period to screen for congenital heart defects and to assess the function of the cardiovascular system. It enables obtaining a three-vessel view (3VV) to show how the superior vena cava, the aorta and the pulmonary trunk relate to each other. A 3VV also provides a view of the thymus gland. Thymic hypoplasia or aplasia, is associated with impaired cell-type immunity. Diagnosis of athymia in neonatal period may prevent complications in adulthood. Methods Using the thymus measurements obtained in echocardiography of neonates delivered in one healthcare centre, a total of 1331 thymus records were collected and statistically analysed. The study was conducted on group of 321 preterm neonates and 1010 full-term neonates. The superior mediastinal view was chosen for thymus measurements, with the parallel vascular system, including the superior vena cava, the aorta and the pulmonary trunk ,with visible branching to the right and left pulmonary artery (3VV). Results Based on a statistical analysis, a correlation was found of 3VV thymus dimensions and thymic index (TI) with body weight, gestational age and body surface area (BSA). These measurements led to the important finding that the TI value depends on thymus width and depth, more prominently the latter. The 3VV measurement of thymus depth alone can serve as a screening tool to assess the size of the gland. Conclusions Inclusion of thymic measurements in neonatal echocardiography protocol can be used as a screening tool to detect thymic hypoplasia or aplasia often associated with impaired cell-type immunity.