title: Sonographic thymic measurements in Down syndrome fetuses.
abstract: OBJECTIVE
  Children with Down syndrome (DS) can have hypoplastic thymuses with an impaired capacity to liberate newly generated T cells. We sought to determine if the size of the thymus in DS fetuses is different from control fetuses.
  
  
  METHODS
  We performed comprehensive prenatal sonographic evaluation that included measurements of the thymus in 874 control fetuses and in 12 DS fetuses. We used graphic comparisons between thymic measurements obtained from the two groups of fetuses and a nested case-control validation study in which DS fetuses were matched for gestational age with control fetuses using a 2-to-1 ratio to make group comparisons.
  
  
  RESULTS
  The plot analysis showed that more than two-thirds of DS fetuses had sonographic signs of thymic hypoplasia. The nested case-control study confirmed that the thymus of DS fetuses was statistically smaller than the thymus of control fetuses [DS transverse diameter 12.3 mm, interquartile range (IQR) 6.2 vs. control 18.1 mm, IQR 4.4; p < 0.001 and, DS perimeter 30.9 mm, IQR 20.1 vs. control 48.6 mm, IQR 20.4; p < 0.01].
  
  
  CONCLUSIONS
  Our findings suggest that the majority of DS fetuses have smaller thymuses than control. Prenatal measurements of the thymus may be clinically useful in the management of DS pregnancies.
authors.affiliation: Department of Obstetrics and Gynecology, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: De Leon-Luis
authors.forename: Joaquín
authors.initials: J
authors.lastname: Santolaya
authors.forename: Francisco
authors.initials: F
authors.lastname: Gamez
authors.forename: Pilar
authors.initials: P
authors.lastname: Pintado
authors.forename: Ricardo
authors.initials: R
authors.lastname: Perez
authors.forename: Luis
authors.initials: L
authors.lastname: Ortiz-Quintana
mesh_terms: D016022:Case-Control Studies; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D013950:Thymus Gland / Q000000981:diagnostic imaging* / Q000196:embryology*; D016216:Ultrasonography, Prenatal