Absent nasal bone at 11-14 weeks of gestation and chromosomal defects.

OBJECTIVE: To examine the association between absence of the nasal bone at the 11-14-week ultrasound scan and chromosomal defects. METHODS: Ultrasound examination was carried out in 3829 fetuses at 11-14 weeks' gestation immediately before fetal karyotyping. At the scan the fetal crown-rump length (CRL) and nuchal translucency (NT) thickness were measured and the fetal profile was examined for the presence or absence of the nasal bone. Maternal characteristics including ethnic origin were also recorded. RESULTS: The fetal profile was successfully examined in 3788 (98.9%) cases. In 3358/3788 cases the fetal karyotype was normal and in 430 it was abnormal. In the chromosomally normal group the incidence of absent nasal bone was related firstly to the ethnic origin of the mother (2.8% for Caucasians, 10.4% for Afro-Caribbeans and 6.8% for Asians), secondly to fetal CRL (4.6% for CRL of 45-54 mm, 3.9% for CRL of 55-64 mm, 1.5% for CRL of 65-74 mm and 1.0% for CRL of 75-84 mm) and thirdly, to NT thickness, (1.8% for NT < 2.5 mm, 3.4% for NT 2.5-3.4 mm, 5.0% for NT 3.5-4.4 mm and 11.8% for NT > or = 4.5 mm. In the chromosomally abnormal group the nasal bone was absent in 161/242 (66.9%) with trisomy 21, in 48/84 (57.1%) with trisomy 18, in 7/22 (31.8%) with trisomy 13, in 3/34 (8.8%) with Turner syndrome and in 4/48 (8.3%) with other defects. CONCLUSION: At the 11-14-week scan the incidence of absent nasal bone is related to the presence or absence of chromosomal defects, CRL, NT thickness and ethnic origin.     

Likelihood ratio for trisomy 21 in fetuses with absent nasal bone at the 11-14-week scan.

OBJECTIVE: To update the likelihood ratio for trisomy 21 in fetuses with absent nasal bone at the 11-14-week scan. METHODS: Ultrasound examination of the fetal profile was carried out and the presence or absence of the nasal bone was noted immediately before karyotyping in 5918 fetuses at 11 to 13+6 weeks. Logistic regression analysis was used to examine the effect of maternal ethnic origin and fetal crown-rump length (CRL) and nuchal translucency (NT) on the incidence of absent nasal bone in the chromosomally normal and trisomy 21 fetuses. RESULTS: The fetal profile was successfully examined in 5851 (98.9%) cases. In 5223/5851 cases the fetal karyotype was normal and in 628 cases it was abnormal. In the chromosomally normal group the incidence of absent nasal bone was related first to the ethnic origin of the mother, being 2.2% for Caucasians, 9.0% for Afro-Caribbeans and 5.0% for Asians; second to fetal CRL, being 4.7% for CRL of 45-54 mm, 3.4% for CRL of 55-64 mm, 1.4% for CRL of 65-74 mm and 1% for CRL of 75-84 mm; and third to NT, being 1.6% for NT < or = 95th centile, 2.7% for NT > 95th centile-3.4 mm, 5.4% for NT 3.5-4.4 mm, 6% for NT 4.5-5.4 mm and 15% for NT > or = 5.5 mm. In the chromosomally abnormal group there was absent nasal bone in 229/333 (68.8%) cases with trisomy 21 and in 95/295 (32.2%) cases with other chromosomal defects. Logistic regression analysis demonstrated that in the chromosomally normal fetuses significant independent prediction of the likelihood of absent nasal bone was provided by CRL, NT and Afro-Caribbean ethnic group, and in the trisomy 21 fetuses by CRL and NT. The likelihood ratio for trisomy 21 for absent nasal bone was derived by dividing the likelihood in trisomy 21 by that in normal fetuses. CONCLUSION: At the 11-14-week scan the incidence of absent nasal bone is related to the presence or absence of chromosomal defects, CRL, NT and ethnic origin.     

孕11—13^＋6周胎儿颈项透明层厚度的超声测量

目的分析孕11～13^＋6周正常胎儿颈项透明层（NT）厚度及其与头臀径的关系。方法选择孕11～13^＋6周头臀径为45～84mm的正常胎儿3224例,超声测量胎儿NT厚度和头臀径,并对头臀径与颈NT厚度进行相关性研究。结果胎儿NT厚度随着头臀径的增加而增厚;中位数预测值从头臀径为45mm时的0．9mm至头臀径为84mm时的1．7mm。结论孕11-13^＋6周正常胎儿NT厚度的参考值范围为早孕期胎儿染色体异常和其他先天性异常的筛查提供了帮助。     

Frontomaxillary facial angle in chromosomally normal fetuses at 11 + 0 to 13 + 6 weeks.

OBJECTIVE: To establish the normal range of the frontomaxillary facial (FMF) angle at 11 + 0 to 13 + 6 weeks of gestation. METHODS: In this prospective study, three-dimensional (3D) volumes of the fetal head were obtained from 500 pregnancies before fetal karyotyping by chorionic villus sampling (CVS), after screening by fetal nuchal translucency (NT) thickness and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 to 13 + 6 weeks. Only cases with a normal karyotype were included in this study. The FMF angle was measured off-line. In a subgroup of 150 cases the FMF angle was measured using 2D ultrasound before obtaining a 3D volume. In 50 cases the 3D volumes were used to measure the FMF angle by the same examiner twice and by another examiner once. RESULTS: The mean FMF angle decreased with crown-rump length (CRL) from 84.3 degrees at CRL 45 mm to 76.5 degrees at CRL 84 mm. There was no significant association between the FMF angle and fetal NT or serum PAPP-A or beta-hCG. In the volumes with paired measurements, the difference between two measurements by the same or two sonographers was < 5% in 95% of the cases. In the cases with paired 3D and 2D ultrasound measurements, the difference in FMF angles was < 8% in 95% of the cases. CONCLUSIONS: At 11 + 0 to 13 + 6 weeks the FMF angle decreases with fetal CRL but is not related to fetal NT or serum biochemistry. The measurement is reproducible and the results obtained by 3D and 2D ultrasound are similar.     

Detailed screening for fetal anomalies and cardiac defects at the 11-13-week scan.

OBJECTIVE: To assess the diagnostic efficacy of the first-trimester anomaly scan including first-trimester fetal echocardiography as a screening procedure in a 'medium-risk' population. METHODS: In a prospective study, we evaluated 3094 consecutive fetuses with a crown-rump length (CRL) of 45-84 mm and gestational age between 11 + 0 and 13 + 6 weeks, using transabdominal and transvaginal ultrasonography. The majority of patients were referred without prior abnormal scan or increased nuchal translucency (NT) thickness, the median maternal age was, however, 35 (range, 15-46) years, and 53.8% of the mothers (1580/2936) were 35 years or older. This was therefore a self-selected population reflecting an increased percentage of older mothers opting for prenatal diagnosis. The follow-up rate was 92.7% (3117/3363). RESULTS: The prevalence of major abnormalities in 3094 fetuses was 2.8% (86/3094). The detection rate of major anomalies at the 11 + 0 to 13 + 6-week scan was 83.7% (72/86), 51.9% (14/27) for NT < 2.5 mm and 98.3% (58/59) for NT >or= 2.5 mm. The prevalence of major congenital heart defects (CHD) was 1.2% (38/3094). The detection rate of major CHD at the 11 to 13 + 6-week scan was 84.2% (32/38), 37.5% (3/8) for NT < 2.5 mm and 96.7% (29/30) for NT >or= 2.5 mm. CONCLUSION: The overall detection rate of fetal anomalies including fetal cardiac defects following a specialist scan at 11 + 0 to 13 + 6 weeks' gestation is about 84% and is increased when NT >or= 2.5 mm. This extends the possibilities of a first-trimester scan beyond risk assessment for fetal chromosomal defects. In experienced hands with adequate equipment, the majority of severe malformations as well as major CHD may be detected at the end of the first trimester, which offers parents the option of deciding early in pregnancy how to deal with fetuses affected by genetic or structural abnormalities without pressure of time.     

Fetal gender assignment by first-trimester ultrasound.

OBJECTIVE: Ultrasound determination of fetal sex can benefit decision-making regarding invasive prenatal testing in pregnancies at risk of sex-linked genetic abnormalities. The aim of this study was to assess the accuracy of fetal sex determination by ultrasound at 12-14 weeks of gestation in a large cohort. METHODS: Fetal gender assessment by transabdominal ultrasound was performed in 656 singleton pregnancies at 12-14 weeks of gestation. The genital region was examined in the mid-sagittal plane. The angle of the genital tubercle to a horizontal line through the lumbosacral skin surface was measured. The fetus was assigned male gender if the angle was > 30 degrees , and female gender if the genital tubercle was parallel or convergent (<10 degrees ) to the horizontal line. At an intermediate angle of 10-30 degrees the gender was not determined. Crown-rump length (CRL) was measured in all cases. RESULTS: Gender assignment was possible in 613 of the 656 (93%) fetuses. Gender identification according to CRL was feasible in 85%, 96% and 97% of the fetuses at gestational ages of 12 to 12 + 3, 12 + 4 to 12 + 6 and 13 to 13 + 6 weeks, respectively. Phenotypic sex was confirmed in 555 newborns. The accuracy of male gender assignment in this group was 99-100% at all ages, and that of female gender assignment was 91.5% at 12 to 12 + 3 weeks, 99% at 12 + 4 to 12 + 6 weeks and 100% at 13 to 13 + 6 weeks. CONCLUSION: Prenatal gender assignment by ultrasound has a high accuracy rate at 12-14 weeks. These results indicate that invasive testing can probably be carried out in fetuses identified as males at this gestational age. However, in fetuses identified as female at a CRL of <62.6 mm, despite the relatively high 91.5% accuracy rate, the decision regarding invasive testing should be postponed until a higher CRL is achieved.     

早孕期诊断胎儿体蒂异常超声与病理对照研究

目的探讨早孕期胎儿体蒂异常超声诊断的临床价值。 方法对2009年1月至2014年7月早孕期在湖北省妇幼保健院超声筛查诊断体蒂异常的17例胎儿超声声像图特征及引产胎儿病理尸检（15例）结果进行对照研究。 结果早孕期诊断体蒂异常的17例胎儿超声表现与中晚孕期相同：腹壁大的缺损及肿块回声,严重脊柱侧弯,肢体异常,颅面缺损,神经管缺陷和脐带极短或缺失。其中多数胎儿（10例）合并心脏,泌尿系统等畸形。17例体蒂异常胎儿早孕期特有的超声表现：头臀径（CRL）测值评估孕周均小于临床孕周;颈项透明层（NT）增厚11例,胚外体腔持续存在13例。妊娠结局：17例体蒂异常胎儿超声检查后胎儿母亲均选择终止妊娠,15例引产胎儿标本尸检证实与产前超声诊断相符合;畸形分类：Ⅰ型3例,以颅面缺陷为主要特征;Ⅱ型12例,无颅面畸形,腹部-胎盘附着为主要特征,8例伴肢体畸形;2例未行病理尸检。17例体蒂异常胎儿产前超声漏误诊心脏及肢体异常9例。 结论早孕期系统超声筛查对检出胎儿体蒂异常有重要临床价值,胎儿体蒂异常合并心脏及肢体异常产前超声易漏诊或误诊。     

Fetal trunk and head volume measured by three-dimensional ultrasound at 11 + 0 to 13 + 6 weeks of gestation in chromosomally normal pregnancies.

OBJECTIVE: To establish the relationship between fetal trunk and head volume measured by three-dimensional (3D) ultrasound and gestational age at 11 + 0 to 13 + 6 weeks of gestation. METHODS: The fetal trunk and head volume were measured using 3D ultrasound in 417 chromosomally normal fetuses from singleton pregnancies at 11 + 0 to 13 + 6 (median, 12 + 0) weeks of gestation. Regression analysis was used to determine the significance of the association between fetal volume and gestational age. The Bland-Altman analysis was used to compare the measurement agreement and bias for a single examiner and between different examiners. RESULTS: The fetal trunk and head volume increased linearly with gestation from a mean of 5.8 mL at 11 + 0 weeks to 33.3 mL at 13 + 6 weeks and 1 SD was 4.4 mL. There was also a significant linear association between fetal volume and crown-rump length (CRL), from a mean of 5.1 mL at a CRL of 45 mm to 37.5 mL at a CRL of 84 mm and 1 SD was 2.7 mL. However, within this gestational range, a doubling in CRL, from a mean of 48 mm at 11 + 0 weeks to 79 mm at 13 + 6 weeks, was associated with a 5-6-fold increase in fetal volume. The mean difference in fetal volume between paired measurements by the same sonographer was -0.87 mL (95% limits of agreement, -2.31 to 4.05 mL) and the mean difference between paired measurements by two sonographers was -1.09 mL (-5.49 to 3.32 mL). CONCLUSIONS: 3D ultrasound can provide a reproducible measurement of the fetal trunk and head volume in early pregnancy. At between 11 + 0 and 13 + 6 weeks there is a 5-6-fold increase in fetal volume but only a doubling in CRL.     

Optimal crown-rump length for measuring the nuchal translucency

PURPOSE: To determine the optimal crown-rump length (CRL) for obtaining nuchal translucency (NT) measurements. METHODS: Women undergoing NT measurements by NT-certified sonographers within a combined screening program over an 18-month period were included in the study if they had a living fetus with a CRL of 45-84 mm. NT measurement success and screen-positive rates, transvaginal sonography (TVUS) use, and reasons for failed NT measurements were compared in 3 groups by CRL corresponding to 11-0/7 to 11-6/7 weeks (45-54 mm), 12-0/7 to 12-6/7 weeks (55-66 mm), and 13-0/7 to 13-6/7 weeks (67-84 mm). RESULTS: Eight hundred thirty-seven women aged 34.9 +/- 4.9 years underwent 1 to 3 NT measurements at a mean CRL of 59.8 +/- 25.0 mm. NT measurements were more successful at 11 and 12 weeks (81.8% and 84.4%) than at 13 weeks (66.9%) (p < 0.001). Screen-positive and TVUS rates, and reasons for failed NT measurements did not vary by CRL. CONCLUSION: NT measurements are most successful at CRL 45-66 mm corresponding to sonographically determined gestational ages of 11-0/7 to 12-6/7 weeks.     

胎儿颅内出血的产前超声特征与妊娠结局

目的探讨胎儿颅内出血的产前超声声像图特征.方法对30例颅内出血胎儿产前及产后颅脑超声声像图进行对照分析.结果30例颅内出血胎儿超声声像图特征:(1)颅内异常回声特征:30例均显示颅内异常占位回声(双侧异常回声14例,单侧异常回声16例),但出血量、出血时间不同异常回声表现不同;其中15例(15/30,新鲜出血期)颅内出血区呈高回声,11例(部分液化期)颅内出血区呈混合性回声,4例(完全液化期)颅内出血区呈囊性无回声.(2)异常回声区边界及血流特征:异常回声区边界清晰,彩色多普勒血流成像示异常回声区内部及周边未见明显彩色血流信号.(3)超声分级诊断与随访结果:超声诊断Ⅰ级颅内出血17例(均为室管膜下出血),表现为单侧或双侧室管膜下高回声区、混合性回声区或囊性无回声区,大小3~21 mm,双侧侧脑室无扩张(侧脑室宽度均<15 mm);胎儿预后较好,颅脑超声随访(12例)均证实为颅内出血,引产1例,失访4例.Ⅱ级颅内出血5例,均无脑室扩张,单侧或双侧侧脑室内高回声区,大小8~28 mm,与脉络丛分界尚清,双侧侧脑室无扩张(侧脑室宽度均<15 mm);产后颅脑超声随访证实2例为颅内出血,引产2例,失访1例.Ⅲ级颅内出血6例,脑室内出血合并脑室扩张,单侧或双侧脑室内呈高回声或混合性回声区(单侧或双侧侧脑室宽度≥15 mm);胎儿MRI诊断颅内出血1例,引产5例,失访1例.Ⅳ级颅内出血2例(双胎1例),Ⅰ~Ⅲ级脑出血合并脑室周围实质内大范围出血,脑室周围实质呈高回声或混合性回声区;胎儿MRI诊断颅内出血1例,2例均引产(1例双胎之一胎死宫内).(4)颅内出血合并异常:合并宫内发育迟缓5例,胎盘异常3例,羊水异常3例.(5)临床结局:14例临床预后较好(Ⅰ级12例,Ⅱ级2例),产后新生儿存活,无严重神经系统并发症;引产10例预后均较差(Ⅰ级1例,Ⅱ级2例,Ⅲ级5例,Ⅳ级2例),失访6例.结论胎儿颅内出血产前超声表现为颅内异常占位回声区,回声边界清晰,其内无血流信号,超声分级诊断有助于判断胎儿颅内出血严重程度,可估测胎儿预后和协助产前咨询.     

Nuchal translucency thickness measurement: repeatability using a virtual ultrasound scanner.

AIM: To use a PC-based virtual ultrasound scanner (VirUS) in the investigation of inter- and intraoperator nuchal translucency (NT) thickness measurement repeatability of experienced ultrasound operators. METHODS: Realistic fetal ultrasound images of defined NT thickness were simulated with VirUS with emulation of scanner gain and time-gain compensation and gain-dependent echo size changes. A set of 50 images was generated with uniformly distributed NT thickness (range, 1-5 mm at 1-mm intervals) and translucency angle (mean +/- standard deviation of +/- 2.52 degrees +/- 1.85 degrees about the horizontal). Operators (n = 13) measured NT thickness in the image set on three occasions separated by at least 1 day, giving 150 measurements per operator (total measurements, 1950). RESULTS: Inter- and intraoperator repeatabilities were +/- 0.41 mm and +/- 0.22 mm, respectively (at the 95% confidence level). There were significant correlations between repeatability and mean measured NT thickness (r = - 0.72, P = 0.005 at 4-mm interval), between gain and mean measured NT thickness (P 相似文献   

Screening for trisomy 21 in monochorionic twins by measurement of fetal nuchal translucency thickness.

OBJECTIVE: To determine whether in screening for trisomy 21 by measurement of fetal nuchal translucency (NT) thickness in monochorionic twin pregnancies it is preferable to use the higher, smaller or average NT. METHODS: We retrospectively examined 769 monochorionic twin pregnancies that had undergone NT screening. The selection criteria were that first, in each pregnancy both fetuses were alive at the 11 to 13 + 6-week scan and second, the fetal karyotype had been determined by prenatal invasive testing or the pregnancy outcome was known. In each pregnancy the risk for trisomy 21 was calculated by a combination of maternal age and fetal NT for crown-rump length (CRL). Three estimates of risk for each pregnancy were made using the higher, smaller and average NT and these were compared for detection and false positive rates. RESULTS: The median maternal age was 33 (range, 16-45) years, the CRL was 62 (range, 45-84) mm and gestational age was 12 (range, 11 to 13 + 6) weeks. Either the fetal karyotype was normal, or phenotypically normal babies were born, in 761 cases. The karyotype was abnormal in eight cases, including six with trisomy 21. The estimated risk using the higher, smaller and average NT was 1 in 300 or more in 6 (100%), 4 (66.7%) and 6 (100%) of the trisomy 21 pregnancies and in 148 (19.4%), 57 (7.5%) and 106 (13.9%) of the normal pregnancies. For a detection rate of 100%, the false positive rates using the higher, smaller and average NT would be 5.1%, 45.9% and 4.2%, respectively. CONCLUSION: In monochorionic twins, effective screening for trisomy 21 is best provided by using the average NT measured in the two fetuses.     

中孕期胎儿系统超声检查切面及临床意义

目的研究中孕期胎儿系统超声检查中的各种切面,探讨这些切面的临床意义。方法总结和归纳我院2000年7月至2009年7月9年间的胎儿系统超声检查的经验,对比分析国外产科超声检查经验和规范,通过研究各种畸形在不同切面上的表现,对中孕期产科超声检查过程中需要检查的切面进行详细研究,规范胎儿系统超声检查的标准切面。结果笔者研究了中孕期胎儿系统超声检查的各个切面,发现32～39个胎儿切面在胎儿超声检查中非常重要,绝大部分胎儿结构畸形可通过这些切面筛查并诊断出来,从而提高胎儿畸形产前检出率。结论胎儿系统超声检查中32～39个切面是中孕期系统超声检查中的重要切面,这些切面的制定和规范,有利于提高胎儿畸形产前检出率,为产前超声诊断规范化培训和质量控制奠定基础。     

Relationship between fetal nuchal translucency and crown-rump length in an Asian population.

OBJECTIVES: To investigate the relationship between the nuchal translucency (NT) thickness and crown-rump length (CRL) in normal Asian fetuses during the first trimester. DESIGN: A prospective observational study was conducted. Ultrasound measurement of NT and CRL was offered in 879 consecutive Taiwanese fetuses between 9 weeks and 14 weeks of gestation. Regression analysis was used to analyze the relationship between the NT thickness and CRL. Fetal sex was also considered in the analysis. The distribution of multiple of median (MoM) values of the NT measurements with CRL in 10-mm intervals and the 95th centile of MoM were also calculated. RESULTS: The present study shows that NT measurements increase with increasing CRL. A fixed cut-off point through the first trimester is not appropriate. The NT thickness has no relationship with fetal sex. Expressing the NT thickness by MoM values provides a simple method for clinical practice. CONCLUSIONS: The present study offers normative data of the fetal NT thickness in an Asian population, which may improve the performance of NT measurement during the first-trimester as a screening tool for chromosomal aberrations or other congenital abnormalities in the first trimester.     

A normal second-trimester ultrasound does not exclude intracranial structural pathology.

OBJECTIVE: To report the prenatal diagnosis and management of 34 fetuses with various intracranial structural pathologies diagnosed following a normal second-trimester ultrasound examination. METHODS: We retrospectively reviewed the images of 203 abnormal central nervous system ultrasound examinations performed between 13 and 37 weeks of gestation at our prenatal diagnosis unit. In 34 (16.7%) of them at least one previous second-trimester ultrasound examination had been performed and considered normal. These 34 fetuses represent the study group. RESULTS: The following intracranial pathologies were diagnosed: dysgenesis of the corpus callosum, ventriculomegaly, cerebral cysts or hemorrhage, migrational disorders, vermian dysgenesis, arachnoid cysts, macrocephaly, enlarged subarachnoid space, brain calcifications and microcephaly. CONCLUSION: A normal second-trimester ultrasound scan does not rule out significant intracranial anomalies. Parents and physicians should be informed about the limitations of second-trimester sonography as far as brain diagnosis is concerned. A repeat third-trimester scan may enable more accurate diagnosis and counseling.     

The variability in the interpretation of prenatal diagnostic ultrasound.

OBJECTIVES: Although prenatal ultrasound is broadly used to detect abnormal fetuses, the variability in the interpretation of second-trimester prenatal ultrasound examinations is unknown. We sought to evaluate the consistency of the interpretation of prenatal ultrasound examinations. DESIGN: Physicians who perform prenatal ultrasound and who participate in the California Maternal Serum Expanded AFP program were asked to interpret a series of test ultrasound examinations. The series of cases was selected to include a random sample of fetal structural abnormalities, ultrasound markers that have been associated with chromosomal abnormalities, and normal cases. Interobserver agreement was evaluated using a kappa statistic for each organ system. The sensitivity and false-positive rate were calculated for detecting specific anatomic abnormalities within each organ system. RESULTS: Of the 210 sonologists eligible for inclusion in the study, completed responses were received from 148 (70%). There was moderate to substantial agreement between physicians in reporting the presence of fetal abnormalities for all organ systems (kappa range 0.40-0.88, P < 0.001). The consistency was highest for the central nervous system (CNS), neck, and face. Within each organ system, the consistency was similar for major structural abnormalities and ultrasound markers of chromosomal abnormalities. The sensitivity ranged from 62% (95% confidence interval (CI) 58-66%) for major renal abnormalities to 91% (95% CI 88-94%) for CNS abnormalities, with corresponding false-positive rates of 7% (95% CI 6-9%) for renal abnormalities and 9% (95% CI 7-11%) for CNS abnormalities. For most organ systems, the sensitivity for detecting ultrasound markers of chromosomal abnormalities was similar to the sensitivity for detecting structural abnormalities. CONCLUSION: There is moderate to substantial agreement in the interpretation of second-trimester prenatal ultrasound examinations. Whether the identification of specific ultrasound abnormalities and markers is overall beneficial to patients remains to be determined.     

Do early pregnancy ultrasound measurements correlate with fetal nuchal translucency at 11-14 weeks?

OBJECTIVE: To assess whether extremes in nuchal translucency (NT) thickness measurements at 11-14 weeks of gestation are preceded by departures from normal in early ultrasound biometry or embryonic heart rate in euploid fetuses. METHODS: This was a retrospective analysis of data from women with singleton pregnancies examined in early pregnancy between June 2002 and January 2003, who subsequently had a nuchal translucency (NT) scan. The early pregnancy scan was performed transvaginally, and the crown-rump length (CRL), mean gestational sac diameter (GS), mean yolk sac diameter (YS) and embryonic heart rate (HR) were measured where possible. At the second scan CRL and NT were measured. RESULTS: A total of 534 singleton pregnancies were included in the analysis. The mean maternal age was 30 (range, 14-45) years, and 59.4% of the patients were nulliparous. The mean CRL was 11.5 (range, 1.4-30.0) mm at the first scan and 62.8 (range, 42.0-88.0) mm at the second scan. GS, YS and HR measurements were obtained in 87.6%, 72.5% and 72.5% of cases, respectively. No statistically significant correlation was observed between NT and Z-scores of early pregnancy: GS (r = 0.013, P = 0.77), YS (r = 0.039, P = 0.44) or HR (r = 0.016, P = 0.76). GS, YS and HR were not significantly different in fetuses with NT measurements below the 10th percentile or above the 90th percentile (P = 0.24, 0.84 and 0.60, respectively). CONCLUSION: Ultrasound biometry and heart rate measured in early pregnancy are not related to nuchal translucency measurements at 11-14 weeks of gestation in chromosomally normal fetuses.     

Relationship between nuchal translucency thickness and prevalence of major cardiac defects in fetuses with normal karyotype.

OBJECTIVE: To define the prevalence of major cardiac defects according to nuchal translucency (NT) thickness at the 11 to 13 + 6-week scan in fetuses with normal karyotype. METHODS: Specialist fetal echocardiography was carried in 6921 fetuses with normal or presumed normal karyotype at a median gestation of 20 (range 12-35) weeks. The indications for fetal echocardiography were increased NT thickness (n = 3444), detailed second-trimester scan either for assessment of risk of chromosomal abnormalities (n = 2980) or previous or family history of fetal defects (n = 497). The cardiac defects were grouped into six functional categories: septal defect, left inflow obstruction, right inflow obstruction, left outflow obstruction, right outflow obstruction and other. RESULTS: Major cardiac defects were identified in 132 (19.1 per 1000) fetuses and the prevalence increased with fetal NT thickness from 4.9 per 1000 in those with NT below the median, to 8.7 for NT between the median and less than the 95th centile, 18.2 for NT between the 95th and 99th centiles, and exponentially thereafter to 35.2, 64.4 and 126.7 for respective NTs of 3.5-4.4 mm, 4.5-5.4 mm and > or = 5.5 mm. There was no obvious difference in the distribution of NT in the different types of cardiac defects. CONCLUSIONS: The prevalence of major cardiac defects increases exponentially with fetal NT thickness and in fetuses with NT of 3.5 mm or more it is higher than in pregnancies with a family history of cardiac defects.     

Three-dimensional ultrasound volume calculations of human embryos and young fetuses: a study on the volumetry of compound structures and its reproducibility.

OBJECTIVE: To evaluate volumetry with three-dimensional (3D) ultrasonography in the assessment of the size of human embryos and fetuses. METHODS: Forty-four healthy embryos/fetuses with crown-rump length (CRL) ranging from 9 mm to 58 mm were studied using a 7.5-MHz annular array transvaginal 3D probe. EchoPAC 3D software was used to calculate the volumes of the head, body and limbs in the same data set by two observers working independently of each other. Regression analysis was used to assess the relationship between estimated volumes and CRL. RESULTS: The embryonic and fetal volume estimates of both observers ranged from a mean of 93 mm3 at 10 mm CRL to a mean of 11 169 mm3 at 55 mm CRL. The volume of the limbs as a proportion of the mean whole-body volume increased from 4.7% at a CRL of 15 mm to 9.3% at a CRL of 55 mm. Limits of agreement between the observers were calculated to be -0.12 +/- 9.2%. CONCLUSION: It is possible to reconstruct complex small anatomic structures and calculate the volumes of human embryos and fetuses in vivo by using dedicated 3D ultrasound equipment. The reproducibility of whole-body volume estimates seems to be high. The limbs represent a significant proportion of the size of the embryonic/fetal body.     

Second-trimester biparietal diameter/nasal bone length ratio is an independent predictor of trisomy 21.

OBJECTIVE: The purpose of this study was to evaluate the association between the second-trimester fetal biparietal diameter/nasal bone length (BPD/NBL) ratio and trisomy 21. METHODS: Thirty-one cases of trisomy 21 for which complete ultrasound images included the nasal bone were identified from the University of Washington prenatal diagnosis database and matched to 136 euploid fetuses based on maternal age, indication for referral, and gestational age. RESULTS: The mean NBL was shorter (mean +/- SD, 2.3+/-1.7 mm versus 3.9+/-1.2 mm; P<.001) and the BPD/NBL ratio was greater (17.7 [range, 6.2-114] versus 11.7 [range, 5.8-80]; P<.001) in the fetuses with trisomy 21. The risk of trisomy 21 increased 2.4-fold (95% confidence interval [CI], 1.7-3.4) with every 1-mm decrease in NBL and increased 1.08-fold (95% CI, 1.03-1.12) with each unit increase in the BPD/NBL ratio (P<.001). A multiple logistic regression model was constructed and included the BPD/NBL ratio, maternal indications (age>or=35 years, positive serum screening results, or both, yielding a risk of <1 per 270 for trisomy 21), and sonographic markers as covariates. The BPD/NBL ratio was found to be an independent predictor of trisomy 21 (odds ratio, 1.08; 95% CI, 1.03-1.11). An analysis of receiver operating characteristic curves revealed an improvement after the BPD/NBL ratio was added to a model containing the current second-trimester screening based on maternal age, serum screening, and sonographic markers (receiver operating characteristic curve area, mean +/-SE, 0.89+/-0.03 for the model with the BPD/NBL ratio versus 0.76+/- 0.06 without the BPD/NBL ratio; P=.009). CONCLUSIONS: The second-trimester BPD/NBL ratio was a significant and independent predictor of trisomy 21. An assessment of the BPD/NBL ratio may improve the diagnosis of trisomy 21 when used with current prenatal screening practices.