The application of magnetic cell sorter (MACS) to detect fetal cells in maternal peripheral blood

OBJECTIVES: The aim of the present study was to investigate the effectiveness of sorting fetal nucleated red blood cells (FNRBC) from maternal peripheral blood, particularly during early gestation periods, by a combination of specific gravity centrifugation and magnetic cell sorter (MACS). METHODS: Without prior knowledge of the gender of the fetus, we determined gender by analyzing a Y-chromosome specific sequence by nested-PCR, using 10 ml of the peripheral blood of healthy primigravida women at different stages of gestation (first trimester: n = 17, second trimester: n = 13, and third trimester: n = 19). The results of this prenatal sex determination were compared to the sex of newborns. RESULTS: The specificity, sensitivity, positive predictive value (PPV) and negative predictive value (NPV) of the present method during the first trimester were 100, 81.8, 100, and 75%, respectively; during the second trimester, 80, 50, 80, and 50%, respectively; and during the third trimester, 25, 63.6, 53.8, and 33.3%, respectively. CONCLUSION: The results show that this prenatal sex determination method has a highly accurate diagnostic rate during the first trimester, suggesting that it could be developed as a practical, non-invasive prenatal diagnostic technique for use during early gestation periods.     

母血中胎儿有核红细胞数量与胎儿异常的关系

目的 :探讨母血中胎儿有核红细胞数量与胎儿异常的关系 ,为将它用于无创性产前诊断提供实验依据。方法 :对孕 6～ 40周的 86例妇女 (包括胎儿正常组 68例、胎儿异常组 1 8例 )的外周血进行单密度梯度离心、瑞氏染色和细胞计数 ,分析母血中胎儿有核红细胞数量与孕周、胎儿异常及胎儿性别的关系。结果 :胎儿正常组 ,母血中胎儿有核红细胞平均数量为 1 4.2 3±1 2 .0 1 /ml,与妊娠周数呈直线相关 (R >R0 .0 5)。胎儿异常组中 ,母血中胎儿有核红细胞平均数量较正常胎儿组显著增加 ,约为 3 8.73± 2 4.97/ml,且与妊娠周数无明显直线相关性。母体外周血中胎儿有核红细胞数量与胎儿性别无统计学相关性。结论 :胎儿发生异常时母血中胎儿有核红细胞数量较正常妊娠时增加。母血中胎儿有核红细胞数量在胎儿正常时随孕周而增加 ,且不受胎儿性别的影响。母血中胎儿有核红细胞计数可以辅助用于产前筛查胎儿异常的发生。     

Non-invasive prenatal detection of paternal origin hb lepore in a male fetus at the 7th week of gestation

OBJECTIVE: To perform a reliable non-invasive prenatal detection of the Hb Lepore paternal mutation and determine the fetal gender in the first trimester of pregnancy. METHODS: DNA was extracted from a serum sample obtained from a pregnant woman at the mid first trimester of gestation. Hb Lepore-specific, mutant and normal, primers as well as Y-chromosome-specific STSs were used to carry out the analysis. RESULTS: Paternal Hb Lepore and the DYS14 and DYZ1 gene-specific sequences were detected in the serum sample obtained at the 7th week of pregnancy. None of the above sequences was detectable in the maternal peripheral blood cell DNA. CONCLUSION: Conventional polymerase chain reaction analysis of cell-free fetal DNA can be used to determine fetal gender and paternal Hb Lepore as early as the 7th week of pregnancy.     

双胎妊娠染色体异常的产前筛查及产前诊断

双胎妊娠发生胎儿畸形、染色体异常的风险较单胎妊娠高。近年来双胎妊娠发生率和高龄产妇数量不断增加,双胎妊娠的早期筛查以及产前诊断十分重要。早孕期,颈项透明层(nuchal translucency,NT)超声筛查是重要手段,不建议单独使用血清学筛查;中孕期超声结构筛查对检出胎儿结构异常有一定意义。无创产前基因检测技术的发展,对降低侵入性产前诊断的风险有重要意义,但由于目前临床证据尚不充分,双胎妊娠行无创基因检测仍需谨慎。     

Influence of gestational age on fetal deoxyribonucleic acid retrieval in maternal peripheral blood

OBJECTIVE: We wanted to verify whether gestational age influences the retrieval of fetal deoxyribonucleic acid in maternal blood to identify the best period for maternal blood sampling for a future noninvasive prenatal diagnoses. STUDY DESIGN: We amplified 81 deoxyribonucleic acid samples extracted from the peripheral blood of 27 pregnant women (18 bearing male fetuses and 9 bearing females) by nested polymerase chain reaction of the Y-specific sequence DYS14. We obtained three blood samples (one per gestational trimester) from each woman. Statistical evaluation was assessed by the McNemar test of symmetry. RESULTS: Polymerase chain reaction results in male-bearing pregnancies differed significantly between the first and second trimesters and between the second and third trimesters (p < 0.025) in parallel with a decrease in sensitivity in the second trimester (67%) compared with the first (94%) and third trimesters (100%). CONCLUSIONS: The drop in sensitivity from the first to the second trimester witnesses a variable concentration of fetal cells in maternal blood, with a negative balance in the second trimester. Therefore, to achieve an adequate polymerase chain reaction accuracy, the choice of gestational age is relevant and the first trimester seems to be more suitable than the second trimester.(Am J Obstet Gynecol 1997;177:22)     

Optimization of nucleated red blood cell (NRBC) recovery from maternal blood collected using both layers of a double density gradient

The isolation of fetal nucleated red blood cells (NRBC) from maternal blood represents a promising approach to non-invasive prenatal diagnosis. However, the number of fetal NRBC in maternal circulation is quite low and therefore difficult to isolate. An enrichment procedure in which both layers from a double density 1.077/1.107 g/ml gradient are collected was optimized, followed by MACS selection using non-commercial monoclonal antibodies. The influence of the delay in processing maternal blood on the NRBC distribution in both interfaces of the gradient was also studied in cord blood and peripheral maternal blood samples. A significant increase in the number of NRBC isolated from maternal blood was achieved by collecting both layers of the double density gradient compared with the previous protocol in which only the lower layer was recovered. Cord blood samples showed significant differences in the number of NRBC recovered when processed at 24 instead of within 3 h. This effect was also observed in the number of NRBC collected only from the upper layer of peripheral maternal blood samples. Therefore, in order to minimize the target cell losses, it is advisable to process the maternal blood samples as soon as possible.     

Normal standards of fetal behavior assessed by four-dimensional sonography.

OBJECTIVE: In this prospective randomized study, fetal behavior was investigated in order to determine the standard parameters of fetal movements and facial expressions in all three trimesters of normal pregnancy. METHODS: Sixty-three pregnant women with singleton pregnancies in all trimesters were included in the investigation. Four-dimensional (4D) ultrasound was performed for each patient over a 30-minute period. Variables of maternal and fetal characteristics including gestational age, eight fetal movement patterns in the first trimester, and sixteen parameters of fetal movement and fetal facial expression patterns in the second and third trimesters were recorded for the construction of fetal neurological charts. RESULTS: In the first trimester, a tendency towards an increased frequency of fetal movement patterns with increasing gestational age was noticed. Only the startle movement pattern seemed to occur stagnantly during the first trimester (p > 0.05). At the beginning of the second trimester, the frequency of fetal movement patterns tended to increase. During the second and third trimester, multiple regression and polynomial regression revealed statistically significant changes in tongue expulsion (p < 0.05), smiling (p < 0.05), grimacing (p < 0.05), swallowing (p < 0.05), eye blinking (p < 0.01), head movements, and all hand to body contact movements (p < 0.01), except for head anteflexion (p > 0.05). There were no statistically significant changes during the second and third trimesters in mouthing, yawning, and sucking (p > 0.05). At the middle of the third trimester, the fetuses displayed decreasing or stagnant incidence of fetal facial expressions except for eye blinking, which showed increased frequency with increasing gestational age. A statistically significant correlation was found between all head movements and hand to body contact patterns during the second and third trimesters except for head anteflexion (r = -0.231; p > 0.05). CONCLUSIONS: The full range of quantitative fetal facial expressions and fetal movement patterns can be assessed successfully by 4D sonography. It is important to be able to assess normal fetal behavior throughout gestation to identify abnormal behavior before birth.     

Invasive und nichtinvasive fetale Chromosomenanalyse

Prenatal chromosomal analysis can be offered for a great number of disorders. The techniques (amniocentesis, chorionic villus sampling, fetal blood sampling, placentocentesis, fetal cells from maternal blood) all involve obtaining fetal cells for analysis. Amniocentesis is performed under guidance with ultrasonography and is usually done between a gestation age (GA) of 14+0 and 17+0 because there is a higher loss rate for early amniocentesis (<14+0 GA). An alternative to amniocentesis is chorionic villus sampling which is usually performed transabdominally between 10+0 and 14+0 GA. The benefit of chorionic villus sampling is that termination of pregnancy can still be performed in the first trimester if fetal abnormality is detected. Fetal blood sampling and placentocentesis are performed in selected cases in the second and third trimester but these procedures should be done only by carefully trained personnel. The genetic analysis of fetal cells from the maternal blood has the advantage of a non-invasive risk-free method for prenatal diagnosis, however, at present the technology is not yet sufficiently advanced to permit routine use.     

Sonographic features of lethal multiple pterygium syndrome at 14 weeks

Lethal multiple pterygium syndrome is a rare inherited disorder. Previous reports suggest that the diagnosis may be based on prenatal sonographic demonstration of severe limb flexion, absence of fetal motion, and a large cystic hygroma in the second and third trimesters. We present the sonographic features and postmortem features of a fetus with lethal multiple pterygium syndrome at 13 weeks of gestation, which shows that the condition can possibly be diagnosed in the first trimester of pregnancy.     

应用表观遗传学方法检测母体循环中游离胎儿DNA

目的:探讨表观遗传学方法检测孕妇血浆中游离胎儿DNA水平的应用价值。方法:随机选择早、中、晚期妊娠孕妇各20例,以非妊娠妇女20例为对照组。提取血浆中的总游离DNA,用甲基化特异性PCR(MSP)方法检测各组血浆标本中目的基因m-maspin(一种肿瘤抑制基因启动子的甲基化序列)、u-maspin(前者的未甲基化序列)的表达水平,再进行相对定量,对妊娠组和对照组样本均数进行统计学分析。结果:(1)m-maspin在妊娠早、中、晚期孕妇血浆中的浓度分别是非妊娠妇女血浆中浓度的1.0、1.1、1.1倍,差异无统计学意义(P>0.05);(2)u-maspin在正常非妊娠妇女血浆中未能检测到,在60例孕妇血浆中57例可检测到,它在孕妇血浆中的浓度随妊娠进展呈升高趋势,中、晚期妊娠妇女血浆中其浓度相对于早期妊娠分别为1.7倍和3.1倍,差异有统计学意义(P<0.01)。结论:m-maspin不是妊娠特异性标志物,u-maspin为妊娠特异性标志物。u-maspin基因可作为孕妇血浆中游离胎儿DNA水平变化的表观遗传学标志,相对于以胎儿性别基因作为遗传学标志的检测方法,它有助于扩大非创伤性产前诊断的临床应用范围。     

Inverse correlation between maternal weight and second trimester circulating cell-free fetal DNA levels

OBJECTIVE: Clinical applications of the analysis of cell-free fetal DNA in maternal plasma and serum are expanding. However, use of fetal DNA during prenatal screening requires knowledge of variables that might affect its levels in the maternal circulation. We conducted this study to estimate the effect of selected demographic factors on fetal DNA levels in the first and second trimesters of pregnancy. METHODS: We developed a database that included fetal DNA levels and clinical information, such as maternal age, ethnicity, weight, and smoking history. We measured fetal DNA levels in maternal plasma and serum using real-time quantitative polymerase chain reaction amplification of a Y chromosome specific sequence. The fetal DNA data from fresh first trimester plasma and previously frozen second trimester serum samples were analyzed separately. Fetal DNA levels were adjusted according to gestational age and storage time and then analyzed in association with the demographic factors. RESULTS: In the first trimester group, no significant association between maternal age, weight, ethnic background, or smoking and plasma fetal DNA levels was observed. In the second trimester group, a significant inverse correlation between maternal weight and serum fetal DNA level was demonstrated (r = -0.26, P =.007). This was especially prominent when the mothers weighed more than 170 lb (P =.001). Maternal age, ethnicity, and smoking were not significantly associated with the second trimester serum fetal DNA levels. CONCLUSION: Fetal DNA levels are affected by maternal weight in the second trimester. A correction for this effect may be needed in larger-scale studies or for future clinical applications that measure cell-free fetal nucleic acids in maternal circulation.     

Normal standards of fetal behavior assessed by four-dimensional sonography

Objective.?In this prospective randomized study, fetal behavior was investigated in order to determine the standard parameters of fetal movements and facial expressions in all three trimesters of normal pregnancy.

Methods.?Sixty-three pregnant women with singleton pregnancies in all trimesters were included in the investigation. Four-dimensional (4D) ultrasound was performed for each patient over a 30-minute period. Variables of maternal and fetal characteristics including gestational age, eight fetal movement patterns in the first trimester, and sixteen parameters of fetal movement and fetal facial expression patterns in the second and third trimesters were recorded for the construction of fetal neurological charts.

Results.?In the first trimester, a tendency towards an increased frequency of fetal movement patterns with increasing gestational age was noticed. Only the startle movement pattern seemed to occur stagnantly during the first trimester (p > 0.05). At the beginning of the second trimester, the frequency of fetal movement patterns tended to increase. During the second and third trimester, multiple regression and polynomial regression revealed statistically significant changes in tongue expulsion (p < 0.05), smiling (p < 0.05), grimacing (p < 0.05), swallowing (p < 0.05), eye blinking (p < 0.01), head movements, and all hand to body contact movements (p < 0.01), except for head anteflexion (p > 0.05). There were no statistically significant changes during the second and third trimesters in mouthing, yawning, and sucking (p > 0.05). At the middle of the third trimester, the fetuses displayed decreasing or stagnant incidence of fetal facial expressions except for eye blinking, which showed increased frequency with increasing gestational age. A statistically significant correlation was found between all head movements and hand to body contact patterns during the second and third trimesters except for head anteflexion (r = ?0.231; p > 0.05).

Conclusions.?The full range of quantitative fetal facial expressions and fetal movement patterns can be assessed successfully by 4D sonography. It is important to be able to assess normal fetal behavior throughout gestation to identify abnormal behavior before birth.     

Detection of gamma-globin mRNA in fetal nucleated red blood cells by PNA fluorescence in situ hybridization

OBJECTIVES: Fetal nucleated red blood cells (NRBC) that enter the peripheral blood of the mother are suitable for non-invasive prenatal diagnosis. The application of peptide nucleic acid (PNA) probes for tyramide amplified flow fluorescence in situ hybridization (FISH) detection of gamma-globin mRNA in fixed fetal NRBC is investigated. METHODS: Hemin-induced K562 cells or nucleated blood cells (NBC) from male cord blood were mixed with NBC from non-pregnant women and analysed using both slide and flow FISH protocols. Post-chorionic villus sampling (CVS) blood samples from pregnant females carrying male fetuses were flow-sorted (2 x 10(6) NBC/sample). Y chromosome-specific PNA FISH was used to confirm that the identified gamma-globin mRNA stained cells were of fetal origin. RESULTS: Flow FISH isolated gamma-globin mRNA positive NBCs showing characteristic cytoplasmic staining were all Y positive. The amplification system generated a population of false positive cells that were, however, easy to distinguish from the NRBCs in the microscope. CONCLUSION: The gamma-globin mRNA specific PNA probes can be used for detection and isolation of fetal NRBCs from maternal blood. The method has additional potential for the study of gamma-globin mRNA levels or the frequency of adult NRBC (F cells) in patients with hemoglobinopathies.     

The effect of maternal hemoglobin concentration on fetal birth weight according to trimesters

Objective: To investigate the relationship between fetal birth weight and maternal hemoglobin concentrations in different trimesters.

Methods: This prospective cross-sectional study comprised 329 women, monitored and delivered between January 2013 and January 2014 in our clinic. Hemoglobin concentrations in all trimesters and all birth weights of the newborns were recorded. Comparisons and correlations were made of the maternal hemoglobin concentrations and birth weights in each trimester.

Results: A positive correlation was determined between fetal weight and increased first trimester maternal hemoglobin concentration (p: 0.025). No correlation was found between fetal weights and second and third trimester hemoglobin concentrations (p?=?0.287, p?=?0.298, respectively). When the effect of independent factors on fetal weight was investigated, it was determined that birth week and first trimester hemoglobin levels were the factors of most influence.

Conclusions: Low hemoglobin concentrations in the first trimester of gestation seem to be associated with low fetal birth weights. Anemia can directly cause poor in utero fetal growth due to inadequate oxygen flow to the placental tissue or it can be an indirect indicator of maternal nutrition deficiency. In both circumstances, this study reveals that treatment of anemia before and in the early stages of pregnancy is directly correlated with better fetal outcomes.     

Contribution of genotyping for fetal sex determination in maternal serum for preimplantation genetic diagnosis of X-linked diseases

OBJECTIVE: Couples with a risk of transmitting X-linked diseases included in a preimplantation genetic diagnosis (PGD) center need early and rapid fetal sex determination during pregnancy in two situations. The first situation corresponds to control of embryo sexing after PGD, the second one being that of couples in PGD program having a spontaneous pregnancy. Determination of fetal sex can be achieved by karyotyping using invasive procedures such as chorionic villus sampling (CVS), amniocentesis or cordocentesis and by non-invasive procedures such as ultrasound (US) examination. CVS is the earliest invasive procedure for fetal sex determination and molecular analysis of X-linked genetic disorders during the first trimester but it is associated with a risk of fetal loss. US allows reliable fetal sex determination only during the second trimester. Recently, reliable non-invasive fetal sex determination was realized by using SRY gene amplification in maternal serum. PATIENTS AND METHODS: We report the prospective use of fetal sex determination in maternal serum in our PGD center. Management of pregnancies was performed using this non-invasive procedure in four cases of embryo sexing control and nine cases of spontaneous pregnancies in couples included in PGD program for X-linked diseases. RESULTS: Fetal sex results using SRY gene amplification on maternal serum were in complete concordance with fetal sex observed by cytogenetic analysis or US examination, as well as at birth. DISCUSSION AND CONCLUSION: This new strategy allowed rapid sex determination during the first trimester and permitted to avoid performing invasive procedures in nine pregnancies.     

Normal standards for fetal neurobehavioral developments--longitudinal quantification by four-dimensional sonography

AIM: To construct normal standards for fetal neurobehavioral development using longitudinal observations through all trimesters by four-dimensional sonography. SUBJECT AND METHODS: A group of 100 healthy normal singleton pregnancies were recruited for longitudinal 4D US examinations to evaluate fetal neurodevelopmental parameters between 7 to 40 weeks' gestation. Variables of maternal and fetal characteristics including gestational age, eight fetal movements patterns in the first trimester and 14 parameters of fetal movement and fetal facial expression patterns recorded thereafter for the construction of fetal neurological charts. RESULTS: Measurement of 7 parameters in the first trimester and 11 parameters in the second and third trimesters correlated with gestational age (P<0.05). Those parameters have been followed longitudinally through all trimesters and showed increasing frequency of fetal movements during the first trimester. A tendency towards decreased frequency of facial expressions and movement patterns with increasing gestational age from second to third trimesters has been noticed. CONCLUSION: With 4D sonography, it is possible to quantitatively assess normal neurobehavioral development. There is urgent need for further multicentric studies until a sufficient degree of normative data is available and the predictive validity of the specific relationship between fetal neurobehavior and child developmental outcome is better established.     

Expandability of haemopoietic progenitors in first trimester fetal and maternal blood: implications for non-invasive prenatal diagnosis

OBJECTIVES: Selective amplification of rare fetal cells in maternal blood is a potential strategy for non-invasive prenatal diagnosis. We assessed the proliferative potential of first trimester fetal progenitors compared to maternal ones. METHODS: Fetal and maternal haemopoietic progenitors were cultured separately and in two model mixtures: (i) co-cultures of male fetal nucleated cells mixed with maternal nucleated cells and (ii) co-cultures of malefetal CD34+ cells with maternal CD34+ cells. Cell origin was detected by X-Y fluorescence in situ hybridisation (FISH) RESULTS: The frequency of haemopoietic progenitors in first trimester fetal blood (predominantly CFU-GEMM) differed from those in peripheral blood from pregnant women (predominantly BFU-e). First trimester haemopoietic progenitors formed larger colonies (p=0.0001) and their haemoglobinisation was accelerated compared to those of maternal origin (p<0.001). CD34+ fetal haemopoietic progenitor cells could be expanded four times more than their maternal counterparts (median 235.8-fold, range 174.0-968.0 vs 71.9-fold, range 41.1-192.0; p=0.003). While selective expansion of fetal cells was not observed in the mononuclear cell model, the CD34+ cell rare event mixtures produced a 463.2-fold (range 128.0-2915.0) expansion of fetal cells. CONCLUSION: Selective expansion of first trimester fetal haemopoietic progenitors may be useful for amplifying fetal cells from maternal blood.     

Improved specificity of NRBC detection in chorionic villus sample supernatant fluids using anti-zeta and anti-epsilon monoclonal antibodies.

OBJECTIVE: Fetal erythrocytes leak from fetal capillaries at the time of chorionic villus sampling (CVS). It has been reported that in approximately 60% of CVS cases fetal nucleated red blood cells (NRBC) can be isolated from the supernatant fluid by immunophenotyping with monoclonal antibody (Ab) against the gamma-chain of fetal hemoglobin and used as an additional source for confirmation of the fetal karyotype. However, the increased prevalence of beta-thalassemia mutations in countries such as Greece results in many pregnant women who produce gamma-positive cells. This makes it difficult to distinguish between the fetal and maternal origin of the NRBC. Use of Abs against embryonic hemoglobin chains zeta and epsilon may increase specificity for fetal NRBC detection. METHODS: Mouse monoclonal Abs against Hb-zeta and Hb-epsilon were used in order to examine if specificity for fetal NRBC detection in CVS supernatant fluids could be improved. 41 samples were studied using anti-zeta and 20 using anti-epsilon monoclonal Abs. RESULTS: Anti-zeta or anti-epsilon positive erythrocytes were, respectively, identified in 52 of 61 CVS samples and anti-zeta or anti-epsilon positive NRBC were present in all cases. The mean number of Hb-positive erythrocytes identified with the anti-zeta Ab was 58 and the mean number of NRBC 29. The mean number of anti-epsilon positive erythrocytes was 30 and of NRBC 23. FISH with X and Y chromosome specific probes was performed in 26 cases and the results were concordant with the CVS karyotype. Statistical analysis using the correlation test showed that anti-zeta and anti-epsilon were more specific for the detection of embryonic NRBCs. CONCLUSIONS: Since embryonic monoclonal Abs show increased specificity, they should be preferentially used for NRBC detection in CVS supernatant fluids. Furthermore, the increased specificity of anti-zeta and anti-epsilon Abs may considerably improve prenatal diagnosis from fetal cells isolated from maternal circulation.     

Non-invasive first trimester determination of fetal gender: a new approach for prenatal diagnosis of haemophilia

Ten carriers of haemophilia referred for prenatal diagnosis were offered first trimester non-invasive fetal gender determination by ultrasound and analysis of free fetal DNA (ffDNA) in maternal plasma in an attempt to reduce the need for an invasive diagnostic procedure in female pregnancies. Although repeat testing was required in three cases, fetal gender was determined correctly in all cases (four females, six males) at a median gestation of 12(+3) (11(+2) to 14(+1)) using both methods. In all cases of a female fetus, the mothers opted not to have invasive testing. Both methods provide a reliable option of avoiding invasive testing in female pregnancies.     

Nasal bone (NB) length measurement in the first trimester of pregnancy in Polish population and its validity as fetal aneuploidy indicator

OBJECTIVES: Dynamic development of prenatal diagnostics is mostly directed towards search for non-invasive screening. The main role of the screening methods is to select high-risk fetal aneuploidy group of pregnant women. The base for the prenatal screening in modern obstetrics is ultrasound scanning. DESIGN: The aim of the study was to estimate typical value range for the fetal nasal bone length measurement (NB) between 11th and 20th week of pregnancy, in Polish population. The second aim was to assess the value of the parameter as an aneuploidy marker. MATERIALS AND METHODS: The study was conducted between 1999-2006, in the 1st Division of Obstetrics and Gynaecology, Medical University in ?ód?. The investigated population comprised 2960 pregnant women. 53 cases of the fetal chromosomal aneuploidies were diagnosed. RESULTS: Typical values for the nasal bone measurement were estimated. The investigations showed that until 13th gestation week, visualization of the presence or absence of the nasal bone on the ultrasound scan is a better marker for fetal aneuploidy diagnosis than the measurement. However, since the 14th week, it is the measurement that becomes the most adequate method of the fetal nasal bone assessment. CONCLUSIONS: (1) We estimated the normal value range for the fetal nasal bone length measurement (NB) between 11 and 20 weeks of pregnancy. (2) The nasal bone length is an useful marker for the fetal aneuploidy. 3. The predictive value of the method suggests the visualization of the nasal bone presence in the 1st trimester of the pregnancy as a screening method. The measurement of the NB proves to be a useful method in the prenatal diagnostic in the 2nd trimester of the pregnancy.