Modern prenatal diagnostics allows not only to assign the child's gender long before his birth, but also helps to detect possible malformations, the majority of which become visible at ultrasonography. One of the important indicators revealed on the first ultrasonography screening is the size of a vorotnikovy zone of a fruit.
Screening of the first trimester
Screening of the first trimester is carried out between the 11th and 14th weeks of pre-natal development of future baby. At the same time the doctor pays special attention to a so-called vorotnikovy zone which size is caused by amount of the accumulated lymphatic liquid in occipital area of a fruit. Increase in its quantity can signal about existence of possible genetic defect, for example, to the trisomiya 21 which is the cause of a Down syndrome.
Sizes of a vorotnikovy zone
The size of a vorotnikovy zone depends on age of a fruit. At the beginning of the 11th week the value up to 2 mm is considered normal, by the end of the 13th week it can reach 2.8 mm. At the same time you should not panic if figures are slightly overestimated. Statistically, 9 of 10 children with a size of a vorotnikovy zone between 2.5 and 3.5 mm are born absolutely healthy. And only when the indicator is significantly overestimated, for example 5-6 mm and more, it is possible to suspect existence of genetic defect. After the 13th week lymphatic system of a fruit is formed, liquid from a vorotnikovy zone spreads on body vessels, and indicators of measurement stop being relevant.
Additional researches
And it is worth understanding that these indicators though are considered as quite important point of prenatal diagnostics, in itself the diagnosis are not. It is only the screening helping to estimate degree of risk of developing of any given disease. Therefore any doctor has no right, relying only on high value of the size of a vorotnikovy zone, to send the woman for abortion. The congestion of lymphatic liquid in a neck not necessarily means that the child has some genetic defect. On the other hand, nobody can guarantee that the fruit with a normal vorotnikovy zone will be born absolutely healthy. Therefore there can be necessary also other researches. For example, kordotsentez or the analysis of amniotic waters, more concrete data on the state of health of the kid allowing to give.
Measurement error
Besides you should not forget also about measurement error probability. The fruit is still so small and to measure it to the tenth part of millimeter quite difficult. And the device can be old, and the doctor not such skilled yet, and the provision of a fruit not the most optimum therefore if when carrying out screening of the first trimester doubtful results were received, it is always worth rechecking them at other expert and on other equipment.