CHROMOSOMAL PATHOLOGY MARKERS IN FETUS AT THE AGE OF 10-13 WEEKS + 6 DAYS
Authors: Prokopchuk N.M. , Antonyuk O.P. , Ivanov Yu.A. , Nikolenko M.I. 
Published: March 2021

The most complete information about chromosomal pathology presence in fetuses of thefirst trimester of pregnancy is provided by the use of complex markers: PAPP-A (plasmaprotein-A associated with pregnancy) + free β-hCG (human β chorionic gonadotropin)ultrasound (CP - collar space + nasal bone) for the 10-14th week of development.Purpose of the work – determination of the risk of chromosomal pathology in fetuses inthe first trimester of pregnancy based on markers: biochemical testing of PAPP + freeβ-hCG from the 10-14th week of pregnancy; Ultrasound investigation (US): measurementof the collar space and nasal bone presence.Material and methods: 258 pregnant women with a high risk of chromosomalabnormalities in the first trimester were examined by means of markers: biochemicaltesting of PAPP + free β-hCG and measurements of the collar space. The values ofthe measured markers are expressed as a constituent of the expected median for thecorresponding gestational term. Medians, the 5th and 95th percentiles, percentage outsidethe expected 5th and 95th percentiles, as well as percentage outside the expected 5th /95th percentiles to establish fetal pathology. The study was performed on an ultrasoundscanner Voluson Expert 8 using a transducer with 3-4D transabdominal RAB 4-8D, RAB6-D, and transvaginal RIC 5-9D. Medical Center "EKHOMED" is engaged in expertultrasound envestigations, as well as invasive examinations, which are required for verification of fetal pathology, is the base of Danylo Halytsky Lviv Medical University,DPGE, Department of Radiation Diagnostics.Results. The analysis was carried out in 258 pregnant women with a high risk ofchromosomal abnormalities in the first trimester using markers: biochemical testing ofPAPP + free β-hCG from 10-14 weeks of pregnancy; measurement of the collar spacethickness and visualization or absence of the nasal bone. The pathology is increasedexponentially with the collar space from 0.2% for those fetuses whose thickness isbetween the 5th and 95th centiles, up to 65% for a thickness of 6.5 mm or more. Inthe group of fetuses with chromosomal abnormalities, about 50% have trisomies 21,25% have trisomies 18 or trisomies 13, 10% have Turner syndrome, 5% have triploidy,and 10% have other chromosomal abnormalities. The combination of collar size andPAPP-A and free ß-hCG testing results in a sensitivity of over 90% and a specificity ofover 95%. The rate of false positives is reduced from 3.0% to 2.5%.Conclusions. The thickness of the collar space in chromosomal abnormalities growsexponentially with the thickness of the collar space from 0.2% for those fetuses whosethickness is between the 5th and 95th centile, up to 65% with a collar space thicknessof 6.5 mm or more. In the group of fetuses with chromosomal abnormalities, about 50%have trisomies 21, 25% have trisomies 18 or 13, 10% have Turner's syndrome, 5% havetriploidy, and 10% have other chromosomal abnormalities. The combination of the sizeof the collar space and PAPP-A and free ß-hCG determinations showed a sensitivity ofmore than 90% and a specificity over 95%.