Abstract
To establish reference ranges for the fetal thymic-thoracic ratio (TT-ratio) and to compare results with those from fetuses with congenital heart defects (CHD) with and without microdeletion 22q11 (del.22q11), a condition known to be associated with a hypoplastic thymus. TT-ratio was defined as the quotient of the anteroposterior thymic to the intrathoracic mediastinal diameters measured in the three vessels and trachea view. This ratio was measured in a prospective cross-sectional study of 302 normal healthy fetuses between 15 and 39 weeks' gestation. The study group comprised two groups: one group (CHDn) consisted of 90 fetuses with CHD and a normal karyotype with no del.22q11 and the other group (CHD(22)) included 20 fetuses with CHD and a normal karyotype but with proven del.22q11. The TT-ratio of the normal fetuses did not show any statistically significant change during gestation, with a mean value of 0.44. The values of all 90 fetuses of the CHDn group were within the normal range and no different from normal fetuses. However, 19 of the 20 (95%) fetuses in the CHD(22) group had a significantly smaller TT-ratio (P < 0.001) compared with both the CHDn group and the normal fetuses, having a mean value of 0.25. The TT-ratio is reliable and easy to obtain during fetal echocardiography. Fetuses with CHD and a low TT-ratio can be considered at high risk of having microdeletion del.22q11.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
