Genetic ultrasound or Genetic echo. It is a type of obstetric ultrasound that consists of evaluating the fetus to demonstrate or rule out any alteration, reporting findings or markers that can guide the identification of fetuses that have chromosomal alterations.
Summary
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- 1 Application
- 2 Epidemiology
- 3 Interpretation
- 4 Sources
App
Ultrasounds to determine genetic markers are usually performed in the first trimester of pregnancy , between weeks 11 and 14. In addition, other biochemical markers are indicated from Week 14 of pregnancy, including maternal serum levels of alpha-fetoprotein (AFP) , to rule out chromosomal disorders in the fetus.
Genetic ultrasound is also indicated for pregnant patients over 35 years of age, because advanced maternal age predisposes to chromosomal non-disjunction and for this reason is associated with the birth of children with chromosomal abnormalities, particularly trisomies 21, 18 and 13.2 .
Epidemiology
Congenital defects are relatively frequent complications, affecting approximately 3% of newborns and causing about 20% of deaths in the neonatal period, as well as being an important cause of morbidity among newborns.
The detection rate of congenital anomalies during the first trimester, between weeks 11 and 14, is 23%, although some more optimistic studies report sensitivities of up to 50% during this period. However, the sensitivity and specificity of ultrasound performed routinely between weeks 16 and 18 increase to 84% and 99.9%, respectively; however, other studies report sensitivities much higher than 92.8% for the detection of abnormalities. serious.
The presence of more than one genetic marker on ultrasound increases the likelihood of chromosomal abnormalities. Moreover, if the ultrasound findings suggestive of disorders in the fetus are accompanied by abnormal values in the biochemistry of the mother’s blood serum.
Interpretation
The genetic echo is usually performed in the second trimester in order to detect abnormalities, including structural defects as well as non-structural defects, which are called genetic markers. The most common observed in second-trimester ultrasound are thickening of the nuchal fold, hyperechoic intestine, shortening of long bones (mainly the humerus and femur), renal pyelectasis, intracardiac echogenic foci, and plexus cysts. choroidal. Many of these findings, however, can be achieved in isolation in euploid fetuses, and appear only temporarily, so their interpretation must be careful.
The progress of ultrasound, with improvements in image resolution, has made it possible to determine with greater precision the prenatal diagnosis of defects at the facial level, including cleft lip and Down syndrome .
