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Sonographic measurement of fetal thymus size in uncomplicated singleton pregnancies
Author(s) -
Tangshewinsirikul Chayada,
Panburana Panyu
Publication year - 2016
Publication title -
journal of clinical ultrasound
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.272
H-Index - 61
eISSN - 1097-0096
pISSN - 0091-2751
DOI - 10.1002/jcu.22419
Subject(s) - medicine , perimeter , percentile , fetus , gestational age , ultrasound , singleton , biparietal diameter , transverse diameter , pregnancy , homogeneous , reference values , nuclear medicine , obstetrics , anatomy , radiology , mathematics , biology , geometry , statistics , combinatorics , head circumference , genetics
Purpose To establish sonographic reference ranges of the normal fetal thymus size between 17 and 38 weeks of gestational age (GA). Methods The study was conducted between April 1 and December 31, 2013. Low‐risk singleton pregnancies without obstetrical and medical complications at the GAs between 17 and 38 weeks were recruited for thymus measurement. The fetal thymus was identified on transabdominal sonography at the three‐vessel view. Maximal transverse diameter, perimeter, and thymus/thoracic ratio were measured. The best‐fit models in predicting thymic dimensions as a function of GA and biparietal diameter (BPD) were determined using regression analysis, and percentile charts for predicting thymic dimensions were constructed. Results A total of 296 singleton pregnancies were recruited in this study. Maximal transverse diameter, perimeter, and thymus/thoracic ratio increased throughout pregnancy. The regression equation for maximal transverse diameter of the thymus as a function of GA was as follows: Predicted mean thymus diameter (mm) = −25.904 + 2.476 × GA − 0.019 × GA 2 ( r = 0.915; p < 0.001) with predicted standard deviations of thymus diameter (mm) = 1.428 + 0.044 × GA ( r = 0.017; p < 0.001). Conclusions Sonographic reference ranges of the normal fetal thymic dimensions between 17 and 38 weeks of GA have been established. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45 :150–159, 2017