Thymus gland Assessment and its Possible Relation with Fetal Growth Restriction

Abstract

Although it is considered an endocrine gland, thymus gland is the main organ of the lymphatic system. Its primary function is to promote the development of specific white blood cells called T lymphocytes." The thymus is special in that, unlike most organs, it is at its largest in children. Once person reach puberty, the thymus starts to slowly shrink and become replaced by fat." Several methods for sonographic thymus measurement have been described. The thymus can be identified on the fetal three- vessel and tracheal view, between the great vessels posteriorly and the chest wall anteriorly. The thymus can be measured lengthwise and crosswise, its circumference and surface area can be measured. 8lThe nomograms for the analysis of the size of fetal thymus were developed in Canada (2007). A relationship was shown between the thymus transverse diameter and the gestational age, the fetal abdominal circumference and femoral length. The average transverse thymus diameter in mm was similar to the AC in cm, especially in the second trimester, which may be very useful information in day-to-day fetal sonography and echocardiography.