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ABSTRACT: To assess thymic size expressed as the thymic-thoracic ratio (TT-ratio) in fetuses with trisomy 21, 18 or 13.
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.
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.
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. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Ultrasound in Obstetrics and Gynecology 12/2011; 40(4):412-7. · 3.01 Impact Factor
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ABSTRACT: We describe a case series of six fetuses with open spina bifida (OSB) from four different prenatal units, where the anomaly was detected at the routine 11-13-week ultrasound examination. Crown-rump length ranged from 49 to 78 mm. All cases were first suspected during nuchal translucency thickness measurement in the mid-sagittal plane of the face. OSB was lumbosacral in five fetuses and cervical in one. The intracranial translucency (IT) was obliterated in two cases, but some fluid was found in the other four cases. However, in all cases the typical landmarks of a normal posterior brain and normal IT were absent. In all six cases the ratio of brainstem diameter to brainstem-occipital bone distance was increased (≥ 1). This detection of an abnormal posterior brain led to a targeted examination and detection of the spinal lesion during the same examination in five cases, whereas in one suspicious case the patient was recalled at 17 weeks, when the abnormality was detected. Two fetuses had both multiple anomalies and trisomy 18. These prospective cases demonstrate the feasibility of using the standard mid-sagittal plane commonly used for NT measurement to assess the IT and the posterior brain and to determine the presence of OSB during NT screening.
Ultrasound in Obstetrics and Gynecology 10/2011; 38(6):722-6. · 3.01 Impact Factor
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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.
Ultrasound in Obstetrics and Gynecology 01/2011; 37(4):397-403. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 10/2010; 36(S1):119-120. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 10/2010; 36(S1):187. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 10/2010; 36(S1):201. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 10/2010; 36(S1):124-125. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 10/2009; 34(S1):35. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 10/2009; 34(S1):125. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 10/2009; 34(S1):177. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 10/2009; 34(S1):146. · 3.01 Impact Factor
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Ultrasound in Obstetrics and Gynecology 10/2009; 34(S1):177. · 3.01 Impact Factor
