ARCHIVEOBSTETRICS AND GYNECOLOGY
International Medical Journal, Vol. 23., Iss. 1, 2017, P. 42−44.
DIAGNOSIS OF ANEUPLOIDY IN THE 1ST AND 2ND TRIMESTERS OF PREGNANCY
Kharkiv Regional Clinical Perinatology Center, Ukraine
Aneuploidy is designated as an abnormal number of chromosomes. The presence of one additional chromosome (trisomy) leads to congenital anomalies of the fetus. Trisomy 21 occurs much more frequently than the rest and is a major cause of mental retardation. Nondisjunction of the chromosomes of the 21st pair during the ovocyte division causes Down's syndrome in 95 % of cases. Trisomies 18 and 13 are less common and are considered lethal abnormalities. Ultrasonography has been used successfully in antenatal diagnosis of trisomy 21 in 80 % of cases, trisomies 18 and 13 in 90−100 %. Ultrasound screening used in the 1st trimester of pregnancy allows chorionic villus sampling to diagnose aneuploidy, and is case it is confirmed, it is considered the reason for abortion. The methods for trisomy 21 risk assessment are ultrasound of the cervical area, fetal nasal bone; Doppler venous flow investigation, analysis of serum pregnancy−related protein markers of the mother, and subunits or the whole molecule of human chorionic gonadotropin. Screening in the 2nd trimester includes ultrasound detection of fetal anomalies and determining the levels of alpha−fetoprotein, beta hCG conjugated estriol and inhibin−A in the blood serum of pregnant. Reasonability of expert advice for choosing the most suitable trisomy risk assessment algorithm is emphasized.
Key words: ultrasound diagnosis, human genome, aneuploidy, Down's, Edwards', Patau's and Turner syndromes.