Down syndrome screening using race-specific femur length

Fetal age assessment based on femur length at 10–25 weeks of gestation, and reference ranges for femur length to head circumference ratios

“…However, maternal, ethnic, and morphometric differences had no impact on FL in the second trimester. This is in line with the findings of Ruvolo et al (13) and Borgida et al (12). The difference we found with the recent British chart (2) is small, 2–3 days, and is presumably caused by using a different measurement technique, rather than study design and statistical methods, which are similar.…”

“…Some investigators have found that fetuses of black mothers have longer fetal FL than fetuses of white mothers (2,11), and Asian fetuses are suggested to have smaller FL (11). Others found little racial variation in fetal FL (12,13).…”

Do Race-Specific Definitions of Short Long Bones Improve the Detection of Down Syndrome on Second-Trimester Genetic Sonograms?

“…Previously published definitions of expected femur and humerus lengths were applied to the study population. The regression formulas used in this study are shown in Table 1 3,7,8 ; "standard" refers to the formulas generated by Nyberg et al 3 without consideration of race; this formula is referred to as standard in that it has been applied previously to the entire population regardless of race. Descriptive statistics were used when appropriate, and a Student t test was used for continuous variables.…”

“…However, a study using race-based definition of expected femur length failed to show an improvement in the detection of Down syndrome in a population of approximately 11,000 patients. 7 Similarly, a study based on a population of 1100 patients did not show a difference in the detection of Down syndrome using race-based definitions of expected humerus length. 8 The conflict between the fact that race affects the observed long bone length but does not affect detection of Down syndrome makes it difficult to counsel women about the impact of race on the association between fetal long bone length and aneuploidy.…”

El femur corto no es un buen marcador de sindrome de down en fetos peruanos

“…Numerosos estudios han documentado que una longitud relativamente corto del fémur fetal en el segundo trimestre de la gestación plantea la sospecha de aneuploidía. Un fémur corto puede tener una sensibilidad del 24% con una tasa de falsos positivos del 4,7% en la identificación de Down síndrome 6 .…”