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Facts and beliefs about Downstream screening


Due to the relative novelty of advanced screening tests, even in professional settings, there are various beliefs and misconceptions about fetal chromosome aberrations (such as those found in the Down).

Facts and beliefs about Downstream screening

Values, not diagnosis

Recently, in the developed world, such as Hungary, fetal chromosomal abnormalitiesscreening tests are carried out in the early stages of pregnancy. It is among these disorders that the Down River is the most distressing for the family and the family. Due to the relative novelty of state-of-the-art screening examinations, there are diverse beliefs and misconceptions about these methods, even in professional circles.
THE szыrхvizsgбlat It is intended to recognize pregnancies in which the chromosome aberration occurs at high rates. He could help the screening test to diagnose chromosomal abnormalities. The screening test "only" shows how much a given pregnancy is valуszнnыsйgthis is the chromosomal disorder tested.
The result of the test can be an index. Which could be for example 1:50, which is high risk from a medical point of view, or 1: 1000, which is considered low risk. In the two examples above, in the first case, fifty-one children would have one, and in the second case, one-thousandth would have a child with Down's dementia. The filters are based on blood and ultrasound examination. The quality of screening tests is determined by the proportion and frequency of patient screenings that occur. It is obviously better to get a higher filter rate with a low survival rate.

The AFP Examination

The most commonly used screening test in Hungary, the 16th Pregnancy AFP screening, is in itself completely inadequate for the diagnosis of Down's syndrome and can only be used for screening. This is because the so-called normal distribution curve of the AFP levels found in healthy and affected pregnancies does not differ significantly from one another. In Hungarian, the probability rate of the test is low, although many coronary findings are produced. Thus, pregnant women are unnecessarily deprived of the fetal water needed for accurate diagnosis, which, even with the help of opened hands, causes a significant loss of weaning. Increased levels of AFP in amniotic fluid can significantly exacerbate neurological damage.
More and more institutions are conducting the so-called triple test exam. This hormone test, also done at week 16, also tests for two other hormones besides AFP, so its probability score is 50-70. If we are testing blood levels of four substances (three tests), the test score for the test is 75 percent.
Update: As of July 1, 2014, the AFP examination in Hungary was terminated (ed.).

Integrated and combined test

The above tests are more up-to-date and much more accurate so-called integrated test And a combined test. Probability scale for each test Over 95 percent, while low, 2-5 percent is the number of coronary findings.
The integrated test of ultrasound and ultrasound performed around the 13th week of pregnancy vйrvizsgбlaton, as well as the four tests mentioned earlier, it gives a fairly accurate result after 16 weeks.
The so-called combined test was performed on the 11th and 13th weeks of pregnancy ultrahangvizsgбlatis here vйrvizsgбlatis below. The method was perfected by the Fetal Medicine Foundation London (FMF). Ultrasound examinations have been standardized. The FMF Risk Analysis Program (software) is used throughout the world to perform tests according to the same technique. Ultrasound technicians undergo thorough training, exams and audits every year. Thus, the data generated by ultrasonic testing can be accurately compared regardless of whether the test is in London, Amsterdam or Budapest. During the ultrasound examination, two important parameters are included in the focus in terms of the filtering of the Down lobe. The thickness of the fetus around the neck of the fetus and the presence or absence of the nasal bone. (Children with Down's disease, including fetuses, tend to have a thick neck and a flat face). The disadvantage of the examination is that the ultrasound examination is time consuming and it takes about 15-25 minutes to perform the correct measurement.
The combined test results on the day of the test. The accuracy of the result is the same as that of the integrated test (95 percent probability ratio with 2 to 5 percent mapping results).

It was not only maternal age

It is also a prerogative that every pregnant baby over 35 years of age should have a chromosome test. State-of-the-art screening tests are specifically for finding young people who are worthwhile and for the elderly who are not worth taking a fetal chromosome test, so interventions are a good idea. These screening tests are suitable for making the decision not to risk the mother's age group, but for the pregnant woman. unique risk take note. It is conceivable that a 39-year-old pregnant woman based on the combined test results in unique risk as much as 20-year-olds (1: 1068), so there is no indication for further testing. Of course, the opposite happens when a 20-year-old pregnant woman is exposed to the individual risk as much as 39-year-olds (1:89), in which case further examinations are worthwhile.
If only maternal age is considered when deciding whether or not to perform a chromosome test, the total number of Down's cases is 30 percent. Down Down 70 percent of cases in mothers younger than 35 years occurs. The current rate in Hungary seems to be slightly better due to the widespread screening tests and the routine 12-week tests. In 2004, approximately 43 percent of people with Down's disease in Hungary were identified during pregnancy.
In an average European country, about 100,000 pregnancies are approx. 140 Down-load is falling. The old age of Szlchennyk is getting older, at present approx. 8 percent of companies over 35 years old. If we performed fetal chromosome screening exclusively on the basis of age group selection, only 42 cases out of 140 pregnancies and 98 cases did not. Of the 8000 chromosome tests performed, 80 would follow.
That is, in age selection, we find 42 patients on 8,000 chromosome tests and 80 miscarriages, and do not find 98, so that we have 7958 redundant chromosome tests. If all 100,000 pregnancies were combined, the screening procedure would highlight 133 patients out of 140 pregnancies and only 7 would have a newborn. An average of 3 numbers of corpus callosum would result in 3,000 unnecessary chromosome tests.
The combined screening capacity of 3,000 chromosome tests per 100,000 pregnancies, 30 miscarriages, shows 133 cases, so that only 7 cases cannot be detected.
I hope that modern screening tests will be available to everyone in Hungary in the short term, and that the practice of chromosome testing will also change.
The author is an obstetrician accredited by the Fetal Medicine Foundation.
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