Thymic-thoracic ratio in fetuses with trisomy 21, 18 or 13.
Ultrasound Obstet Gynecol
; 40(4): 412-7, 2012 Oct.
Article
en En
| MEDLINE
| ID: mdl-22173875
OBJECTIVES: To assess thymic size expressed as the thymic-thoracic ratio (TT-ratio) in fetuses with trisomy 21, 18 or 13. METHODS: The TT-ratio, the quotient of the anteroposterior thymic and the intrathoracic mediastinal diameter, was measured in 65 trisomic fetuses between 15 and 36 weeks' gestation, including 30 cases with trisomy 21, 19 with trisomy 18 and 16 with trisomy 13. In addition these 65 fetuses were divided into two groups, according to whether they showed growth that was appropriate-for-gestational age (AGA) (n = 39) or intrauterine growth restriction (IUGR) (n = 26). Measurements were compared with reference ranges from 302 normal fetuses. RESULTS: The TT-ratio was low in 27.7% (n = 18) of the 65 fetuses with aneuploidy. In comparison to normal fetuses (mean TT-ratio, 0.44), those with trisomy 18 or 21 had a significantly smaller TT-ratio (mean, 0.38 (P < 0.001) and 0.40 (P < 0.05), respectively), while those with trisomy 13 did not (mean, 0.43). These values were not as low as those observed previously in fetuses with del.22q11, suggesting a mechanism involving accelerated thymic involution rather than primary thymic hypoplasia. Furthermore, the TT-ratio was significantly lower than normal in both AGA (P < 0.05) and IUGR (P < 0.001) fetuses. CONCLUSION: Fetuses with trisomy 18 or 21, but not trisomy 13, have a small thymus, suggesting accelerated thymic involution in utero. IUGR may contribute to the reduced thymic size in trisomy 18 fetuses. Trisomy 21 fetuses seem to have additional factors leading to a small thymus which could be a possible confirmation of the reduced immune response observed in fetuses and neonates with Down syndrome.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Tórax
/
Timo
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Síndrome de Down
/
Trastornos de los Cromosomas
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Retardo del Crecimiento Fetal
Tipo de estudio:
Diagnostic_studies
/
Prognostic_studies
Límite:
Adult
/
Female
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Humans
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Male
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Pregnancy
Idioma:
En
Revista:
Ultrasound Obstet Gynecol
Asunto de la revista:
DIAGNOSTICO POR IMAGEM
/
GINECOLOGIA
/
OBSTETRICIA
Año:
2012
Tipo del documento:
Article
País de afiliación:
Alemania
Pais de publicación:
Reino Unido