Measurement Of Nuchal Translucency Thickness Research Articles

Measurement of Nuchal Translucency Thickness in First Trimester Ultrasound Foetal Images Using Markov Random Field

Background The first-trimester ultrasound assessment of nuchal translucency (NT) thickness has lately been recommended as the most helpful sign in early screening for prenatal chromosomal disorders. Increased foetal NT thickness between 11 and 13+6 weeks of gestation is a frequent phenotypic manifestation of chromosomal abnormalities as well as a variety of foetal deformities and genetic disorders. Purpose At the moment, clinicians conduct the measurement manually. The measurement may take a long time to complete, requires highly competent operators, and is susceptible to mistakes. So, an automatic method is required for NT measurement. Materials and Methods This study proposes a Markov random Field-based approach for contextually segmenting the NT area from foetal pictures and offering a quick and inexpensive diagnostic even during the early stages of pregnancy. Results Proposed method gives maximum NT thickness error 0.03 and minimum NT thickness error 0.04. Conclusion The proposed research work developed a prototype for an automated NT thickness measuring system. This study proposes an MRF-based model for segmentation and detection of NT area from foetal pictures which gives error is less than other methods.

Atypicality index: avoiding false reassurance in prenatal screening.

To demonstrate the application of the atypicality index as an adjunct to first-trimester risk assessment for major trisomies by the combined test. This was a study of 123 998 Danish women with a singleton pregnancy who underwent routine first-trimester screening, including risk assessment for major trisomies. An atypicality index, which is a measure of the degree to which a profile is atypical, was produced for measurements of fetal nuchal translucency thickness and maternal serum free β-human chorionic gonadotropin and pregnancy-associated plasma protein-A. The incidence of adverse pregnancy outcome, including miscarriage, intrauterine death and termination of pregnancy, was tabulated according to the screening result and atypicality index. In pregnancies with low risk and those with high risk for major trisomies according to the combined screening test, the incidence of adverse pregnancy outcome increased with increasing atypicality index. In pregnancies with a low risk for trisomies and atypicality index of ≥ 99%, the incidence of adverse outcome was 5.1 (95% CI, 3.4-7.6) times higher compared with that in low-risk pregnancies with a typical measurement profile, reflected by an atypicality index of < 80%. Similarly, in high-risk pregnancies, the incidence of adverse outcome was 7.9 (95% CI, 4.4-14.5) times higher in those with an atypicality index of ≥ 99% compared to those with an atypicality index of < 80%. Using individual profile plots, we were able to demonstrate a transparent and intuitive method for visualization of multiple variables, which can help interpret the individual combination of measurements and level of atypicality. In pregnancies undergoing first-trimester combined screening and classified as being at low risk for major trisomies, profiles that are typical of pregnancies with normal outcome provide additional reassurance, whereas those with an atypical profile may warrant further investigation. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Role of Ultrasound in Early Detection of Molar Pregnancy

OBJECTIVES The objective of this study was to investigate the role of ultrasound in the detection of early pregnancies presenting with placental molar changes. METHODOLOGY This retrospective study was carried out at Radiology department of Hayatabad Medical Complex, Peshawar, between Aug 2020 and July 2021. All cases suspected of molar changes were evaluated from 10-14 weeks of gestation. The patient were referred to our department because of fetal abnormality, maternal disease or age and family or previous pregnancy history or were identified from an ongoing ultrasound screening study for aneuploidy by measurement of fetal nuchal translucency thickness. Transabdominal or transvaginal sonography was used to examine the fetus and placenta. RESULTS Total 85 patients of molar pregnancies were enrolled in the study. Age ranged between 20-45 years with a mean age of 32.5 years. There were 60(70.6%) complete moles (CM) and 25(27.4%) partial moles (PM) were suspected on ultrasound. In case of complete mole coexisting with a normal singleton or twin pregnancy, the molar placenta was clearly separated from the normal placenta, whereas with partial moles the molar structures were dispersed inside the placental mass. CONCLUSION Ultrasound detection of molar pregnancy remains a diagnostic challenge. Data suggest that there has been an increase in both the predictive value and the sensitivity of ultrasound over time; however, the diagnostic criteria remain ill defined. Prior to managing a miscarriage, being aware of the possibility of molar pregnancy will guide treatment and allow for adequate follow-up.

Relation Between Increased Fetal Nuchal Translucency Thickness and Chromosomal Defects in Northern Vietnam.

ObjectiveTo examine the prevalence of all chromosomal defects amongst fetuses with increased nuchal translucency thickness (NT).MethodsThis is a retrospective study amongst pregnant women indicated for amniocentesis by nuchal translucency above 3.0 mm and consent to the study. A total of 2,720 cases were recruited during the six-year period from 2015 to 2020. All singleton pregnancies were offered fetal karyotype when the fetal nuchal translucency was ≥2.5 mm. The prevalence of chromosomal defects was divided into five NT categories: 2.5-3.4 mm, 3.5-4.4 mm, 4.5-5.4 mm, 5.5-6.4 mm, ≥6.5 mm.ResultsThe study identified 2,720 amniocentesis for increased NT. The mean maternal age was 29.19 (range 17-46) years, and the mean fetal crown-rump length was 66.9 (range 45-84) mm. The fetal karyotype was abnormal in 560 (20.6%) participants. The most frequent chromosomal disorders were trisomy 21 (55%), trisomy 18 (11.2%), trisomy 13 (3.9%), 45,XO (2.7%). The prevalence of chromosomal aberrations was ranged from 17.9% (NT between 2.5-3.4 mm) to 29.7% (NT≥6.5 mm). A majority of fetuses with trisomy 13, 18, or 21 has NT measurement lower than 5.5 mm. In those with Turner syndrome, there was no difference between the group with NT <5.5 mm and the group with NT ≥5.5 mm. Increased maternal age is a risk factor for chromosomal aberrations with the rate increased from 17.6% at the youngest maternal age of 30-34 to 34% at maternal age of 35-39 and to 50% at maternal age of ≥40.ConclusionIn fetuses with increased NT, more than a half of the chromosomal abnormalities were affected by defects other than trisomy 21. The distribution of NT was different between Turner syndrome and trisomy 13, 18, 21 syndromes. Women aged 35 years or older had a higher risk of chromosomal aberrations.

Ultrasound image based fully-automated nuchal translucency segmentation and thickness measurement

The nuchal translucency (NT) detection and thickness measurement is a milestone in the prediction of the abnormalities in addition to chromosomal disorders in a fetus in ultrasound imagery. Nuchal translucency is an accumulation of fluids just at bottom of the foetal neck which is closely associated with chromosome abnormalities with cardiac arrest within the pregnancy period of the first trimester. At the hospital, the sonographers manually estimate the thickness of the mid-sagittal plane of nuchal translucency, which is a significant marker for prenatal screening. Such a conventional process done by a technician is quite time-consuming and requires a skilled technician. Within this methodology, an automatic NT detection method based on SIFT keypoint and GRNN is proposed in the mid-sagittal plane. This Non-invasive approach is crucial not just for the assessment of NT, as well as for the detection of extreme deformities and the identification of high-risk pregnancies. The proposed method is tested on a large image dataset which shows that the proposed technique has better accuracy than well-known state of the art methods. The proposed SIFT and GRNN based method have an error of 0.02 which is very less compared to the SVM, ANN, NB and KNN.

First trimester combined screening in patients with systemic lupus erythematosus: impact of pre-analytical variables on risk assessment

BackgroundPrenatal diagnosis of fetal trisomy 21 and other chromosomal abnormalities is based on invasive tests, such as amniocentesis and chorionic villus sampling, which are carried out in women identified through screening as being at high risk for these abnormalities. The most widely used method of screening is the first-trimester combined test which utilizes maternal age, and measurements of fetal nuchal translucency thickness (NT) and maternal serum pregnancy-associated plasma protein-A (PAPP-A) and free β-human chorionic gonadotropin (hCG).ObjectivesTo assess the influence of SLE on the levels of NT, PAPP-A, and β-hCG and whether any alterations in such levels may increase the rate of false positives and the subsequent number of invasive tests.MethodThis was a prospective first-trimester screening study for trisomies 21, 18, and 13 by a combination of maternal age, fetal nuchal translucency thickness, and serum PAPP-A and β-hCG at King’s College Hospital, London, between March 2006 and February 2011. The study population included 47 cases with maternal SLE and 45,493 without SLE. The results of biomarkers in the SLE and non-SLE groups were compared.ResultsIn the SLE group, compared to the non-SLE group, there were no significant differences in median maternal age, fetal NT, or serum PAPP-A MoM, but serum free β-hCG MoM was increased (1.402, IQR 0.872–2.290 vs 0.994, IQR 0.676–1.508).ConclusionIn first trimester screening for trisomies, the measured value of free ß-hCG should be adjusted for maternal SLE to avoid false positive results and overuse of invasive tests.

The Fetal Profile - More Than Just NT

The midsagittal view of the fetal profile is essential in first trimester screening at 11 + 0 to 13 + 6 weeks of gestation. None of the standard sections in prenatal medicine is as well defined and undergoes such a strong quality assurance program. These requirements were recently challenged by the introduction of cell-free DNA screening. The fetal profile view was previously only needed for the appropriate measurement of the fetal nuchal translucency thickness. In recent years, it became evident that there are many more anomalies or markers for fetal defects that can be seen in this section such as spina bifida, facial clefts or retrognathia. The aim of this review is to summarize the additional information that can be gained from the fetal profile view.

Early Detection of Down Syndrome Marker by Measuring Fetal Nuchal Translucency Thickness from Ultrasound Images during First Trimester

Objectives: Nuchal Translucency (NT) thickness measurement is a Down syndrome marker for chromosomal abnormalities which is detected by non-invasive test during first trimester. Methods: In this paper, a computerized method to measure NT thickness is proposed. It consists of region of interest extraction, NT segmentation using morphological operation with Otsu thresholding. The NT thickness is measured from the segmented area. The performance is analyzed on 80 ultrasound fetal images. Findings: Proposed approach for NT measurement is implemented in MATLAB software. Experimental results show that NT thickness for normal foetus is 1.99±.62 mm and abnormal foetus is 4.10±.90 mm during first trimester of pregnancy from 11 to 13+6 weeks of gestation. The proposed algorithm efficiently computes NT measurement and produces consistent result during first trimester in singleton pregnancies. Applications/Improvements: Proposed semi-automated technique helps the medical sonographer for accurate NT thickness measurement to detect Down syndrome marker during first trimester ultrasound scan.Keywords: Down Syndrome, Morphological Operation, Nuchal Translucency, Trimester, Thresholding

Nuchal translucency distributions for different chromosomal anomalies in a large unselected population cohort.

To describe the distribution of the fetal nuchal translucency thickness (NT) according to type of chromosomal aberration in a large unselected population. Data on pregnancies with an NT measurement performed at gestational age 11 + 3 - 13 + 6 weeks from 2008 to 2011 were retrieved from the Danish National Fetal Medicine Database. Information on any genetic analysis for aneuploidy performed pre- or postnatally was also obtained. The abnormal results were grouped into 14 types of chromosomal anomalies. Distributions of NT measurements were summarized by aberration and compared with the normal/no karyotype group. A total of 215 223 singleton pregnancies were included in the cohort; 10548 had a normal karyotype and 1286 had an aberration. Plots of the NT measurements showed that like trisomy 21, 18 and 13 and monosomy X, the distribution for the unbalanced translocations was shifted towards larger NTs. The distributions for the balanced translocations, the uncommon trisomies and the triploidies more closely resembled that of the normal/no karyotype population. Fetuses with aneuploidies have NT distributions visually different from normal fetuses, with the exception of triploidies and uncommon autosomal trisomies. The distributions differ in shape according to type of chromosomal anomaly. © 2015 John Wiley & Sons, Ltd.

Maxillary gap at 11-13 weeks' gestation: marker of cleft lip and palate.

To describe a new sign of cleft lip and palate (CLP), the maxillary gap, which is visible in the mid-sagittal plane of the fetal face used routinely for measurement of nuchal translucency thickness. This was a retrospective study of stored images of the mid-sagittal view of the fetal face at 11-13 weeks' gestation in 86 cases of CLP and 86 normal controls. The images were examined to determine if a maxillary gap was present, in which case its size was measured. In 37 (43.0%) cases of CLP the defect was isolated and in 49 (57.0%) there were additional fetal defects. In the isolated CLP group, the diagnosis of facial cleft was made in the first trimester in nine (24.3%) cases and in the second trimester in 28 (75.7%). In the group with additional defects, the diagnosis of facial cleft was made in the first trimester in 46 (93.9%) cases and in the second trimester in three (6.1%). A maxillary gap was observed in 96% of cases of CLP with additional defects, in 65% of those with isolated CLP and in 7% of normal fetuses. There was a large gap (>1.5 mm) or complete absence of signals from the maxilla in the midline in 69% of cases of CLP with additional defects, in 35% of those with isolated CLP and in none of the normal controls. The maxillary gap is a new simple marker of possible CLP, which could increase the detection rate of CLP, especially in isolated cases.

Detection of Fetal Chromosomal Anomalies

In the Netherlands, first-trimester combined testing (FCT), including the measurement of fetal nuchal translucency (NT) thickness, has been offered to all pregnant women since 2007. Since 2014, noninvasive prenatal testing (NIPT) has been offered to women with an elevated trisomy risk determined by FCT. Because high NT is associated with other anomalies and genetic syndromes beyond trisomies 13, 18, and 21, NIPT is not offered when NT is 3.5 mm or greater. As NIPT becomes less expansive and more widely available, it may replace FCT. This study examines the question as to whether NIPT should replace FCT, how many pregnancies with fetal chromosomal anomalies other than trisomies 13, 18, and 21 and with NT of 3.5 mm or greater would remain undetected. This retrospective cohort study used data from the Department of Obstetrics of the University Medical Center Utrecht, including all fetuses referred because of an NT of 3.5 mm or greater between January 2008 and January 2013. All pregnancies had NT measurements, and risks for trisomies 13, 18, and 21 were calculated. Patients offered amniocentesis or chorionic villus sampling and second-trimester ultrasound if they had NT of 3.5 mm or greater. Outcome for pregnancy included born alive–normal outcome, born alive–abnormal outcome, termination of pregnancy, or fetal demise. Of 25,057 NT measurements obtained on singleton pregnancies during the study period, 225 (0.9%) had an NT of 3.5 mm or greater. Of those, prenatal array analysis and/or karyotyping were performed in 221 (93.8%). A chromosomal anomaly was identified in 103 (48.8%) of the 225 fetuses/newborns, and in 79 (77.7%), the anomaly was trisomy 13, 18, or 21. Of the remaining 24 pregnancies, 11 resulted in fetal demise, 10 had detection of fetal ultrasound anomalies, and 3 had a chromosomal anomaly, but normal ultrasound findings and no fetal demise. Of those, 1 anomaly was a 47,XXX karyotype, 1 had 2 de novo deletions, and 1 had a paternal deletion causing Prader-Willi syndrome. In the cohort of 25,057 pregnancies, a protocol of NIPT rather than NT measurement and a second-trimester ultrasound would have missed a chromosomal anomaly in only 0.01%. If NIPT is offered to all pregnant women, the value of NT measurement in detecting fetal chromosomal anomalies would be small.

Nuchal translucency in normal fetus and its variation with increasing crown rump length (CRL) and gestational age.

Nuchal translucency (NT) is the fluid collection behind the fetal neck which can be measured by ultrasound at 11-14 weeks of gestation. Increase in the nuchal translucency thickness is associated with various congenital anomalies. To study the relationship between nuchal translucency thickness, crown rump length and gestational age in normal fetus. Prospective analytical study conducted on 211 pregnant women from March 2011 to August 2012. Measurement of Nuchal translucency thickness and crown rump length was performed by ultrasound at 11-14 weeks of gestation. The relationship between nuchal translucency thickness, crown rump length and gestational age was studied by using linear regression analysis. The mean CRL was 63.67+13.48mm (range 41.2-88mm) and mean NT thickness was 1.55+0.35mm (range 0.8-2.7mm), respectively. The median gestational age was 12.9 weeks. The regression equation which shows relation between median NT thickness and CRL was described as follows: expected NT thickness = 0.013CRL+0.725, (R2 = 0.258, p <0.001). There was increase in the incidence of NT thickness more than or equal to 2.5mm; 1.7% in fetus between 12-12.9 weeks of gestation to 15.1% in fetus between 14.0-14.9 weeks. Our study offers normative data of NT thickness in normal fetus, which can be used as reference to screen various chromosomal and congenital abnormalities between 11- 14 weeks of gestation. NT thickness increased with increasing CRL and a false positive rate increases with increasing gestational age.

TRANSLUCENCIA NUCAL FETAL UN MARCADOR DE ALTERACIONES CROMOSÓMICAS EN EL PRIMER TRIMESTRE

Objetivo: Se evalúa la efectividad de la medición de la translucencia nucal en un examen de ultrasonido rutinario para la detección prenatal de síndrome de Down. Material y métodos: Estudio ecográfico entre las 10 y 14 semanas de edad gestacional para medición de la translucencia nucal, a fin de determinar la asociación de incremento de la translucencia nucal y un cariotipo fetal anormal. Resultados: Un total de 423 pacientes únicas y un embarazo gemelar fueron estudiadas. Hubo 410 fetos con valores de 3 mm o menos, de los cuales nacieron 409 productos normales y un feto con trisomía 13. De un total de 14 fetos con valores mayores de 3 mm de translucencia nucal encontramos 3 bebes normales, 7 bebes con trisomía 21, dos bebes con síndrome de Turner y 2 muertes fetales intrauterinas sin estudio genético. Se realizó 64 amniocentesis para cultivo de células fetales, 5 estudios cromosómicos en productos abortados espontáneamente y un estudio a un bebe nacido vivo con malformaciones. Conclusión: Este estudio demuestra que la medición de la translucencia nucal en el primer trimestre es un método efectivo de despistaje de anomalías cromosómicas fetales y que es posible la implementación de un programa de screening en la práctica rutinaria.

Segmentación y conteo de las líneas de la nariz del feto en imágenes ecográficas de las 11-13+6 semanas de gestación

&lt;p&gt;&lt;span&gt;Este documento presenta un método para la segmentación de la nariz y el posterior conteo de las líneas correspondientes a la piel, el hueso nasal y la punta de la nariz en imágenes de ultrasonido fetales 2D del primer trimestre de gestación, de 11 a 13 semanas y 6 días (11-13&lt;/span&gt;&lt;span&gt;&lt;sup&gt;+6 &lt;/sup&gt;&lt;/span&gt;&lt;span&gt;semanas). La presencia de las tres líneas del área nasal es una de las características que debe cumplir el feto en la ecografía para garantizar la confiabilidad de la medición del grosor traslucencia nucal. Dicha medición se emplea para identificar la posible existencia de síndromes o anomalías cromosómicas. El método se aplica a la región correspondiente al corte sagital medio de la cabeza donde se han resaltado las regiones con mayor intensidad. La segmentación es jerarquica: primero, se identifica la región de la nariz a través de máximos regionales y alta excentricidad; posteriormente las líneas ya mencionadas son extraídas con agrupamiento basado en K-medias y morfología matemática. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;Dada la incertidumbre entre las imágenes con respecto a posición fetal, resolución, nivel de ruido y rango dinámico, los resultados obtenidos van desde casos en los que no se encuentra la región de interés, hasta otros en los que son claramente identificables las líneas.&lt;/span&gt;&lt;/p&gt;

Fetal right ventricular contraction and relaxation times at 11–13 weeks' gestation on speckle tracking imaging

To examine the contraction time and relaxation time of the right ventricle at 11-13 weeks' gestation in trisomy 21 and euploid fetuses by speckle tracking ultrasound imaging. Measurement of fetal nuchal translucency (NT) thickness, Doppler assessment for tricuspid regurgitation and reversed A-wave in the ductus venosus (DV) and fetal echocardiography were performed immediately before chorionic villus sampling for fetal karyotyping at 11-13 weeks' gestation. Digital videoclips of the four-chamber view of the fetal heart were recorded and analyzed offline using speckle tracking imaging software. The contraction time, which is the time between the highest and lowest peaks in the right ventricular area, and relaxation time, which is the time between the lowest and the subsequent highest area peak, were measured and expressed as a percentage of the duration of the cardiac cycle. Values in trisomy 21 and euploid fetuses were compared. Mean contraction time and relaxation time in 119 euploid fetuses were 52.1% (95% CI, 51.6-52.8%) and 47.8% (95% CI, 47.2-48.4%), respectively. In 21 trisomy 21 fetuses, mean contraction time was significantly higher (57.0% (95% CI, 55.2-58.9%); P<0.01) and relaxation time lower (42.9% (95% CI, 41.1-44.8%); P<0.01) than in euploid fetuses. Multiple regression analysis showed that significant contributions to contraction time and relaxation time were provided by fetal karyotype, NT and tricuspid regurgitation, but not by reversed A-wave in the DV or the presence of a cardiac defect. In first-trimester fetuses with trisomy 21 and in euploid fetuses with increased NT and tricuspid regurgitation there is evidence of increased right ventricular contraction time and shortening of the relaxation time.

Multivariate analysis identifies the estradiol level at ovulation triggering as an independent predictor of the first trimester pregnancy-associated plasma protein-A level in IVF/ICSI pregnancies

Can independent predictors of pregnancy-associated plasma protein-A (PAPP-A) levels be identified in a group of women who conceived following IVF/ICSI? The significantly decreased PAPP-A level in IVF and ICSI pregnancies compared with non-IVF/ICSI pregnancies was correlated strongly with the serum estradiol (E2) level at ovulation triggering. The first trimester prenatal combined screening test for fetal aneuploidies in pregnancies conceived following assisted reproduction techniques (ART) is complicated by an alteration of the maternal biomarkers free β-hCG and PAPP-A, causing a higher false-positive rate compared with pregnancies which are conceived naturally. The use of controlled ovarian stimulation prior to IVF/ICSI is suggested to be the principle reason for these alterations of biomarkers in ART pregnancies. Between January 2010 and December 2011, 1474 women who conceived naturally and 374 women who conceived following IVF (n = 89), ICSI (n = 204) or intrauterine insemination (IUI, n = 81) were included in this retrospective study. Only singleton pregnancies were eligible for this study. For all women, serum analysis was performed in the same clinical laboratory. Measurement of nuchal translucency (NT) thickness was performed by four physicians belonging to the same infertility centre. First-trimester combined screening test of aneuploidy parameters (maternal age, PAPP-A and free β-hCG, NT thickness) were compared between non-ART and ART (IVF, ICSI and IUI) singleton pregnancies. Next, a minimal threshold E2 level at ovulation triggering was suggested for IVF/ICSI pregnancies above which the PAPP-A levels were significantly decreased compared with non-ART pregnancies. Finally, a multivariate analysis was performed to reveal independent predictors of PAPP-A level in IVF/ICSI pregnancies. We showed a decrease of the multiple of the median (MoM) PAPP-A level in IVF and ICSI singleton pregnancies compared with non-ART singleton pregnancies (P < 0.001), with MoM values of 0.74 (0.16-3.16) and 0.81 (0.12-4.61) versus 0.98 (0.14-5.76), respectively. Analysis of variance of the overall model was highly significant (Fisher test 3.76, P = 0.01), indicating that the model explains a significant portion of the variation in the data. No difference in PAPP-A level was found between non-ART and IUI pregnancies. The free β-hCG level and NT thickness did not differ between ART and non-ART pregnancies. PAPP-A levels in IVF and ICSI pregnancies were strongly correlated with the E2 level at ovulation triggering. We showed by multivariate analysis that an E2 cut-off level of 1300 pg/ml at the time of ovulation could predict a significantly lower PAPP-A level at first trimester combined screening (β -0.239 ± 0.088, P < 0.005). The measures of biochemical markers can differ between laboratories and with the used equipment; therefore, extrapolation of the E2 cut-off level to other infertility centres should be undertaken with caution. One should be careful when using correction factors for ART patients undergoing the first trimester combined screening test. The proposed E2 cut-off level may help to identify a subgroup of women within the population of ART patients for whom use of a correction factor is justified. None.

Impact of chorionicity on first‐trimester nuchal translucency screening in ART twin pregnancies

Nuchal translucency (NT) measurement in assisted reproduction treatment (ART) twins is less extensively investigated. Therefore, the present study compared NT measurements of spontaneously conceived twins with ART twins in dichorionic (DC) and monochorionic (MC) pregnancies. Retrospective analysis of 706 unaffected twins between 11 + 0 and 13 + 6 weeks conceived either spontaneously (n = 362) or with ART (n = 344). The group with spontaneous conception included 234 DC (64.6%) and 128 MC (35.4%) pregnancies. In the ART group, 326 were DC (94.7%) and 18 were MC (5.3%). NT values were transformed into multiples of median (MoM). In the DC group, no significant differences between ART and spontaneously conceived twins (NT MoM 1.06 ± 0.28 vs 1.03 ± 0.29; p > 0.05) were observed. NT MoM of MC ART twins was higher compared with spontaneous MC twins (1.23 ± 0.82 vs 0.99 ± 0.27; p = 0.011). Although the incidence of twin-to-twin transfusion syndrome (TTTS) was higher among ART twins (11.1% vs 4.7%), inter-twin NT difference was similar between pregnancies with TTTS (0.42 ± 0.21) or without (0.40 ± 0.71). Measurement of NT thickness in DC ART twins achieves comparable results with twins conceived spontaneously. Conclusions in MC twins are limited; however, higher NT MoM was not related to TTTS or selective intrauterine growth restriction.

Role of second‐trimester ultrasound in screening for Down syndrome

Role of second‐trimester ultrasound in screening for Down syndrome

Variaton of nuchal translucency with increasing crown rump length and gestational age in normal singleton pregnancies

This study was undertaken to estimate ultrasound measurement of nuchal translucency (NT) thickness in normal fetuses between 11 and 13.6 weeks of gestation.The aim of this study was to establish normative data of nuchal translucency distribution in singleton pregnancies.600 fetuses with known normal outcome were included in this study. The distribution of median values of NT thickness with crown rump length(CRL) in 10 mm intervals and 95th percentile were calculated with linear regression method .False positive rates with increasing gestational age were studied. This study offers a normative data of fetal NT thickness in normal pregnancy, which can be used as a reference for screening chromosomal aberrations or other congenital abnormalities in the first trimester.

First‐trimester screening for chromosomal abnormalities by integrated application of nuchal translucency, nasal bone, tricuspid regurgitation and ductus venosus flow combined with maternal serum free β‐hCG and PAPP‐A: a 5‐year prospective study

To investigate the performance of first-trimester screening for chromosomal abnormalities by integrated application of nuchal translucency thickness (NT), nasal bone (NB), tricuspid regurgitation (TR) and ductus venosus (DV) flow combined with maternal serum free β-human chorionic gonadotropin (fβ-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at a one-stop clinic for assessment of risk (OSCAR). In total, 13,706 fetuses in 13,437 pregnancies were screened for chromosomal abnormalities during a period of 5 years. Maternal serum biochemical markers and maternal age were evaluated in combination with NT, NT + NB, NT + NB + TR, and NT + NB + TR + DV flow data in 8581, 242, 236 and 4647 fetuses, respectively. In total, 51 chromosomal abnormalities were identified in the study population, including 33 cases of trisomy 21, eight of trisomy 18, six of sex chromosome abnormality, one of triploidy and three of other unbalanced abnormalities. The detection rate and false-positive rate (FPR) for trisomy 21 were 93.8% and 4.84%, respectively, using biochemical markers and NT, and 100% and 3.4%, respectively, using biochemical markers, NT, NB, TR and DV flow. While risk assessment using combined biochemical markers and NT measurement has an acceptable screening performance, it can be improved by the integrated evaluation of secondary ultrasound markers of NB, TR and DV flow. This enhanced approach would decrease the FPR from 4.8 % to 3.4 %, leading to a lower number of unnecessary invasive diagnostic tests and subsequent complications, while maintaining the maximum level of detection rate. Pre- and post-test genetic counseling is of paramount importance in either approach.