Sonographic screening for fetal aneuploidies

J. Szabo

Künye

Sonographic screening for fetal aneuploidies. Perinatoloji Dergisi 2002;10(3):169-169

Yazar Bilgileri

J. Szabo

University of Szeged Department of Medical Genetics , Faculty of Medicine - HU

Yazışma Adresi

J. Szabo, University of Szeged Department of Medical Genetics , Faculty of Medicine - HU,

Yayın Geçmişi

Çıkar Çakışması

Çıkar çakışması bulunmadığı belirtilmiştir.

First-trimester screening of fetal chromosomal abnormalities by chorionic villus sampling (CVS) w a.s introduced at Szeged in 1982. The indication of the procedure was mainly the advanced maternal age (>35 years) (85%). However, only a small proportion of children (7 % in Hungary, 17% in Finnland, 12.9 % in USA) were born to women age 35 years or older (Ventura, 2000). Following the maternal age indication as a guideline to screen aneuploidies, we were able to identify only a quarter of Down syndrome pregnancies, even if all women older than 35 years requested invasive procedures (CVS, amniocentesis). Consequently, advanced maternal age was not too good selection criterion for efficient prenatal screening of fetal chromosomal (and other) abnormalities due to the well-known controversy, that younger women have the majority of pregnancies, and younger women give birth to the majority of children with Down syndrome.

This controversy represented a great need for offering "some prenatal screening/diagnostic measures" to the younger (<35 yrs) pregnant population and we decided to develop a method for "in utero finding" defected fetuses irrespective of maternal age. We kept an eye on two criteria: the method should be unrisky and should effectively select pregnancies with fetuses of normal and abnormal karyotype. The idea came from practice, namely: if a pediatrician could suspect Down syndrome by looking at the affected neonate on the base of trisomic features caused by "extra" chromosome, a sonographer should do the same by looking at the first trimester embryo. Further speculation was that the "extra" chromosomal material express more pronounced features in the early pregnancy. So we hypothesized that trisomic features predictive for trisomy 21 could be ultrasonically recognized as early as the first trimester. The development of high-resolution ultrasound technique in the mid-80ths gave an outstanding opportunity to approach the intrauterine first-trimester embryo for detailed examination (sonoembryology). Therefore, from 1986 we examined each pregnancy with trisomy 21 fetuses, for finding some sonographic "attitude" that can differentiate aneuploid fetuses from ones with normal karyotype. Reexamining the trisomic fetuses with ultrasound an increased fluid accumulation in the fetal occipital and neck region had been found irrespective of the maternal age in a significant proportion of the fetuses with abnormal karyotype. The increased nuchal edema, which we called first-trimester simple hygroma (FITSH), enlighted the possibility of a prospectice screening in the general population.