Sonographic features of trisomy 18 at midpregnancy

OBJECTIVE: To evaluate the sonographic characteristics of the fetuses with trisomy 18 at 16-22 weeks of gestation. METHODS: The subjects were recruited from pregnant women undergoing prenatal sonographic examinations at 16-22 weeks of gestation and subsequently proven to be trisomy 18. The results of ultrasound findings were retrospectively reviewed in 25 cases with chromosomes which were confirmed as trisomy 18. RESULTS: All cases had at least one abnormal sonographic finding. There was only one case that had no structural abnormality, but fetal growth restriction was documented. The common sonographic findings included fetal growth restriction, choroid plexus cysts, cardiac anomalies, clenched hand, omphalocele and cleft lip. Fetal growth restriction was the most common finding demonstrated in nearly half of all cases. Other less common findings were diaphragmatic hernia, abnormal head shape, polyhydramnios, single umbilical artery. CONCLUSION: Nearly all fetuses with trisomy 18 had characteristic sonographic patterns of abnormalities demonstrated at midpregnancy. Detailed ultrasound at midpregnancy could effectively screen fetuses with trisomy 18 for further genetic testing.     

Prenatal diagnosis of a fetus with distal 10q trisomy.

Distal 10q trisomy is a well-defined but rare syndrome. Most cases are diagnosed in infancy or in childhood and rarely include prenatal findings. We present a case of fetal distal 10q trisomy with abnormal prenatal sonographic findings. A 19-year-old primigravida was referred for genetic counselling at 18 gestational weeks because her husband had a familial history of congenital anomalies. Genetic amniocentesis was thus performed and showed fetal distal 10q trisomy (10q24.1-->qter), 46,XX,der(22)t(10;22)(q24.1;p11.2)pat, resulting from paternal t(10;22) reciprocal translocation. Level II ultrasonograms further demonstrated bilateral hydronephrosis, ventricular septal defect and facial dysmorphism ascertained by three-dimensional ultrasound. The pregnancy was terminated at 22 gestational weeks. Post-mortem autopsy confirmed the sonographic findings. We suggest that abnormal prenatal sonographic findings such as cardio-vascular, renal and facial malformations should alert cytogeneticists to search for subtle chromosomal abnormalities.     

9例18三体综合征胎儿的产前诊断

目的探讨利用孕妇血清筛查和胎儿超声筛查进行18三体综合征胎儿产前诊断的有效性。方法对36例首诊主诉为产前筛查胎儿18三体高危、92例首诊主诉为胎儿超声有异常发现的孕18~32周孕妇共128例，进行羊膜腔穿刺羊水细胞培养、或脐血管穿刺脐血细胞培养染色体分析。结果128例胎儿核型中，9例为18三体综合征，2例为其它染色体异常，染色体异常发现率为8．59％（11／128）。首诊主诉为18三体高危发现18三体4例，异常发现率11．11％（4／36）；首诊主诉胎儿超声异常发现18三体5例，其它染色体异常2例，异常发现率7．61％，其中2例18三体合并有筛查高危和超声异常。结论孕妇血清生化指标筛查结合胎儿超声检查是产前检出18三体胎儿的有效筛查手段。     

中晚孕期18-三体综合征胎儿的超声特征

目的:研究中晚孕期18-三体综合征胎儿超声影像的变化。方法:回顾分析经羊膜腔穿刺、脐血管穿刺胎儿染色体分析确诊为18-三体的胎儿24例的临床资料和超声影像特征。结果:24例18-三体胎儿中,22例超声影像有变化,占全部病例的91.7%;最常见的超声变化是心脏畸形,共15例,占62.5%;其它常见的异常有脉络膜囊肿、脐带异常、肢体异常、宫内生长迟缓、脑室扩大、小脑延髓池扩大等;还可见颅骨变形、颜面裂、颈项皮肤增厚、消化道闭锁、腹壁缺损、膈疝、肾盂轻度积水、羊水过多等。结论:超过90%的18-三体胎儿中晚孕期可发现超声影像改变,中晚孕期胎儿超声检查是产前筛查18-三体胎儿的有效手段。     

Prenatal sonographic findings in 207 fetuses with trisomy 21

OBJECTIVE: The objective was to evaluate the contribution of second trimester ultrasound examination to the prenatal diagnosis of trisomy 21 in 207 fetuses with this aneuploidy. The type and frequency of abnormal sonographic findings were determined. Possible multiple malformation patterns, characteristic of trisomy 21 were sought. STUDY DESIGN: Singleton fetuses that had prenatal sonography during the second trimester, then underwent cytogenetic evaluation in our institution, made up the study population. The sonographic findings of 207 fetuses with trisomy 21 were analyzed. RESULTS: Between 1990 and 2004, fetal karyotyping was performed in 22,150 patients for different indications. An abnormal karyotype was diagnosed in 514 cases (2.3%); among them 207 fetuses with trisomy 21 were detected (40.3%). Abnormal sonography was seen in 63.8% of the cases. Structural anomalies were detected in 28.5% of the trisomy 21 fetuses, among them cardiac defects (15.9%), central nervous system anomalies (14.5%), and cystic hygromas (6.8%) were the most common. Of the minor markers, increased nuchal translucency (28%), pyelectasis (20.3%), and shorter extremities (8.7%) were common findings. CONCLUSIONS: Appropriate diagnosis of structural anomalies, looking for relatively easily detectable minor markers and incorporating fetal echocardiography into the second trimester sonographic protocol, may increase the contribution of mid-trimester ultrasound examination to diagnosing trisomy 21.     

Latent class analysis applied to patterns of fetal sonographic abnormalities: definition of phenotypes associated with aneuploidy.

The aim of the present study was to generate different latent variables that classify the major chromosome aneuploidies using frequency and patterns of fetal sonographic abnormalities in a large database. A total of 1867 fetuses with sonographic abnormalities recorded in a database at New England Medical Center from January 1995 to March 1998 were available for the statistical analysis. Included within this group were 61 aneuploid fetuses, including 11 with 45,X, 30 with trisomy 21, 14 with trisomy 18 and 6 with trisomy 13, 40 structural malformations and/or sonographic markers were detected in these 61 aneuploid fetuses. The ability of malformations and sonographic markers to generate different groups of phenotypes was evaluated by means of latent class analysis, using the 61 affected cases. Four different classes were generated with the hypothetical assumption that each of them could satisfactorily identify a respective fetal aneuploidy represented in the study group. Among 40 fetal malformations and/or sonographic markers, the most important findings in generating specific karyotypic groups were cystic hygroma (class 1), duodenal atresia (class 2), holoprosencephaly (class 3) and omphalocele (class 4), respectively. Accuracy of the classification was 72 per cent for Turner syndrome (class 1), 74 per cent for Down syndrome (classes 1 and 2), 88 per cent for trisomy 13 (class 3) and 93 per cent for trisomy 18. The frequency of associated malformations detected sonographically can help to define a phenotype that is likely to be representative of a specific aneuploidy. Before the definitive karyotype is available or, in cases in which patients refuse an invasive prenatal diagnostic procedure, this may improve antenatal clinical management.     

Prenatal diagnosis of trisomy 9

Fetal trisomy 9, especially its nonmosaic form, is a rare chromosomal abnormality and there are only 8 cases reported to have been sonographically detected in the prenatal period. We report a case of nonmosaic fetal trisomy 9, mimicking trisomy 13 on sonographic findings at 32 weeks' gestation. Although the incidence of trisomy 9 is rare, diagnosing trisomy 9 is important because the sonographic features are similar to those of trisomies 13 and 18, and cannot to be identified by routine fluorescencein situ hybridization. Because nonmosaic trisomy 9 is universally lethal, correct diagnosis and appropriate counseling is essential in patient care and clinical management.     

Correlation of prenatal ultrasound diagnosis and pathologic findings in fetuses with trisomy 13

OBJECTIVES: This study was conducted to compare the prenatal ultrasound findings and postmortem pathologic findings of fetuses with trisomy 13. METHODS: Of 22 150 fetal chromosome analyses, 28 fetuses with trisomy 13 were diagnosed between 1990 and 2004. Findings of second-trimester sonography and subsequent fetal autopsy were compared by organ system, and their correlation was assigned to one of three categories based on the degree of agreement. RESULTS: Of the total of 79 abnormalities that were found on autopsy, prenatal sonography showed 48 (60.8%). The agreement was more than 75% of all abnormalities of these systems: central nervous system (CNS) (76.5%), facial abnormalities (76.5%), urinary system (81.8%) and fetal hydrops (100%), whereas the sensitivity of sonography was lower in these organ systems: heart (53.3%), extremities (12.5%) and abdominal abnormalities (33.3%). In 39.2% of the cases, autopsy findings were not detected by sonography. These additional findings at autopsy involved mainly three organ systems: heart, face and extremities. Some ultrasound findings (n = 17) were not verified at autopsy; most of them were quantitative markers (mild ventriculomegaly, mild pyelectasis). CONCLUSION: Our results indicate that thorough sonographic examination of the fetal face (including ears) and extremities (including hands and feet) with an extensive use of fetal echocardiography may increase the sensitivity of prenatal sonography in detecting trisomy 13.     

Sonographic diagnosis of Down syndrome in the second trimester

We report a sonographic sign consisting of increased skin or soft tissue thickening at the back of the fetal neck during the second trimester, which correlates well with the diagnosis of Down syndrome. Eight hundred consecutive sonograms were performed in conjunction with genetic amniocentesis where four fetuses had trisomy 21 (Down syndrome) by karyotype. Two or 50% had sonographic findings consistent with Down syndrome. Recently we described a retrospective series where 904 sonograms were performed at the time of amniocentesis and seven fetuses had trisomy 21 on cytogenetic analysis. The abnormal sonographic finding at the back of the neck was present in three of those seven cases. Combining these series, 1704 fetuses were examined and 11 cases of Down syndrome were diagnosed cytogenetically. Five of the 11 or 45% had an abnormal sonogram suggestive of Down syndrome. Two of these were patients undergoing sonography for ascertainment of dates at 16 weeks and submitted to amniocentesis solely on the basis of this sonographic finding.     

18-三体综合征胎儿超声声像特征分析

目的分析18-三体综合征胎儿超声声像特征,以期早期诊断与处理。方法回顾分析经染色体核型分析确诊的18-三体儿12例超声检查的资料。结果全部18-三体儿存在二个或以上异常超声声像表现。其中,胎儿生长受限、羊水过多表现率最高,各为58.3%;其次是心脏畸形,50.0%;再其次是脉络丛囊肿、单脐动脉、脑发育不全、上肢发育异常。在〈28周的胎儿中,超声异常的表现率最高的是心脏畸形、脉络丛囊肿,各为66.7%,其次是胎儿生长受限、羊水过多,各为50.0%。胎儿生长受限主要表现为股骨长度发育落后于正常。结论超声检查是产前筛查18-三体儿的有效手段。     

Chromosomal defects and associated malformations in fetal cleft lip with or without cleft palate

OBJECTIVE: To describe the incidence, associated features including chromosomal defects in fetuses, with cleft lip and/or palate and assess the need for karyotyping. METHODS: Retrospective study of 62 cases of prenatally diagnosed facial cleft lip and/or palate in a tertiary fetal medicine unit between January 1991 and December 1999. Chromosome analysis was performed in all fetuses with associated ultrasound findings and in 14 (39%) fetuses with isolated facial clefts. RESULTS: Associated abnormalities were detected in 26 (42%) of the 62 fetuses of which 22 (35%) fetuses had multiple other abnormalities. Central nervous system abnormalities and limb malformations were the most common. Three fetuses had genetic syndromes confirmed after birth. All fetuses with isolated clefts were chromosomally normal, whereas 15 of the 26 with additional abnormalities (58 or 24% of the total group) had chromosomal defects (eight cases of trisomy 13, five of trisomy 18, one unbalanced translocation between chromosomes 7 and 8, and one deletion 4p-). All 22 women who chose not to undergo fetal karyotype analysis delivered phenotypically normal infants. There were five midline clefts; each of them was associated with additional sonographic findings and four were associated with holoprosencephaly. CONCLUSION: Isolated facial clefting is not associated with an increased risk for chromosomal defect. Amniocentesis is recommended when facial cleft is found in association with additional ultrasonographic abnormalities as it is unnecessary for isolated clefts.     

Outcome of cystic hygroma in fetuses with normal karyotypes depends on associated findings

OBJECTIVE: To determine the associated diagnostic findings which are linked with adverse fetal outcome in nuchal cystic hygroma. STUDY DESIGN: Based on a series of 32 cases, we determined the sonographic morphology of the hygroma, associated structural anomalies, karyotypes and autopsy findings. Intrauterine fetal death, spontaneous abortion and abnormal karyotypes were assigned as adverse outcome parameters. RESULTS: The mean gestational age at diagnosis was 14.4 weeks (range 10-21). There were 18 nonseptated and 14 septated hygromas. Besides hygroma, associated sonographic detectable structural anomalies were observed in 17 cases (53.1%). The greatest number of associated sonographic anomalies were hydrops (31.3%), generalised skin oedema (6.3%) and pterygium colli (6.3%). Cytogenetic analysis revealed an abnormal karyotype in 13 of 26 (50%) invasive procedures. Turner syndrome and Trisomy 18 (both 15.4%) were the most frequent cytogenetic abnormalities. Autopsy was performed in 24 cases and 16 cases (66.7%) had an associated autopsy finding to hygroma colli. The most frequent associated autopsy findings were limb and craniofacial anomalies (both 25%). Only 3 (9.4%) mothers gave birth to healthy newborns. The overall fetal adverse outcome rate was 68.8% (22 cases). CONCLUSIONS: Fetuses with NCH are at high risk for adverse outcome and detailed prenatal diagnosis including invasive procedures should be offered. According to the presented autopsy findings, to determine fetal outcome in NCH cases with normal karyotypes, detailed sonography should be concentrated beside the exclusion of fetal heart defects and existence of hydrops fetalis, on the skeletal, urogenital and craniofacial anomalies, as these might cause severe morbidity.     

Integrated ultrasound and biochemical screening for trisomy 21 using fetal nuchal translucency,absent fetal nasal bone,free beta-hCG and PAPP-A at 11 to 14 weeks

BACKGROUND: Screening for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thickness and maternal serum free beta-hCG and pregnancy-associated plasma protein-A (PAPP-A) at 11 to 14 weeks of gestation is associated with a detection rate of 90% for a false-positive rate of 5%. Recent evidence suggests that in about 70% of fetuses with trisomy 21, the nasal bone is not visible at the 11th- to 14th-week scan (Cicero et al., 2001). The aim of this study was to examine whether fetal NT thickness and the level of maternal serum biochemical markers is independent of the presence or absence of the nasal bone, and to estimate the performance of a screening test that integrates the two sonographic and the two biochemical markers. METHODS: This was a retrospective case-control study comprising 100 trisomy 21 and 400 chromosomally normal singleton pregnancies at 11 to 14 weeks of gestation. Ultrasound examination was carried out for measurement of fetal NT and assessment of the presence or absence of the fetal nasal bone. Maternal serum free beta-hCG and PAPP-A were measured using the Kryptor rapid random-access immunoassay analyser (Brahms Diagnostica GmbH, Berlin). The distribution of fetal NT, maternal serum free beta-hCG and PAPP-A in trisomy 21 fetuses with absent and present nasal bone was examined. RESULTS: The nasal bone was absent in 69 and present in 31 of the trisomy 21 fetuses. There were no significant differences in median maternal age, median gestational age, NT delta, free beta-hCG MoM and PAPP-A MoM in trisomy 21 fetuses with and without a visible nasal bone. For a false-positive rate of 5%, it was estimated that screening with the four markers in combination with maternal age would be associated with a detection rate of 97%. For a false-positive rate of 0.5%, the detection rate was 90.5%. CONCLUSIONS: An integrated sonographic and biochemical test at 11 to 14 weeks can potentially identify about 90% of trisomy 21 fetuses for a false-positive rate of 0.5%.     

Maternal serum biochemistry at 11-13(+6) weeks in relation to the presence or absence of the fetal nasal bone on ultrasonography in chromosomally abnormal fetuses: an updated analysis of integrated ultrasound and biochemical screening

BACKGROUND: Screening for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thickness and maternal serum free beta-hCG and pregnancy associated plasma protein-A (PAPP-A) at 11-13(+6) weeks of gestation is associated with a detection rate of 90%, for a false-positive rate of 5%. Recent evidence suggests that in about 70% of fetuses with trisomy 21 the nasal bone is not visible at the 11-13(+6) week scan and that the frequency of absence of nasal bone differs in different ethnic groups. In addition, there is a relationship between absent nasal bone and nuchal translucency thickness. In a preliminary study we showed that while PAPP-A levels were lower and free beta-hCG levels were higher in trisomy 21 fetuses with an absent nasal bone, this difference was not statistically different. In fetuses with trisomy 13 and trisomy 18, there is also a high (57 and 67%) incidence of an absent nasal bone. The aim of this present study was to extend our examination of whether the level of maternal serum biochemical markers is independent of the presence or absence of the nasal bone in cases with trisomy 21 and to ascertain if any differences exist in cases with trisomies 13 and 18. METHODS: This study data comprised 100 trisomy 21 singleton pregnancies at 11-13(+6) weeks of gestation from our previous study and an additional 42 cases analysed as part of routine OSCAR screening. A total of 34 cases with trisomy 18 and 12 cases with trisomy 13 were also available. Ultrasound examination was carried out for measurement of fetal NT and assessment of the presence or absence of the fetal nasal bone. Maternal serum free beta-hCG and PAPP-A were measured using the Kryptor rapid random access immunoassay analyser (Brahms Diagnostica AG, Berlin). The distribution of maternal serum free beta-hCG and PAPP-A in chromosomally abnormal fetuses with absent and present nasal bone was examined. RESULTS: The nasal bone was absent in 29 and present in 13 of the new trisomy 21 cases and in 98 (69%) and 44 respectively in the combined series. For the trisomy 18 cases, the nasal bone was absent in 19 (55.9%) cases and in 3 (25%) of cases of trisomy 13. There were no significant differences in median maternal age, median gestational age, NT delta, free beta-hCG MoM and PAPP-A MoM in trisomy 21 fetuses with and without a visible nasal bone, and similarly for those with trisomies 13 or 18. For a false-positive rate of 5%, it was estimated that screening with the four markers in combination with maternal age would be associated with a detection rate of 96% of cases with trisomy 21. For a false-positive rate of 0.5%, the detection rate was 88%. CONCLUSIONS: There is no relationship between an absent fetal nasal bone and the levels of maternal serum PAPP-A or free beta-hCG in cases with trisomies 13, 18 or 21. An integrated sonographic and biochemical test at 11-13(+6) weeks can potentially identify about 88% of trisomy 21 fetuses for a false-positive rate of 0.5%.     

The prenatal diagnosis of Pierre-Robin sequence.

The purpose of this study was to evaluate the spectrum of prenatal sonographic and chromosomal findings, associated anomalies and perinatal and neonatal outcomes in cases with Pierre-Robin sequence. All cases (20) with Pierre Robin sequence, who were born at China Medical College Hospital between 1990 and 1997, were included and analysed in this series. 12 pregnancies (60 per cent) were complicated by polyhydramnios and 9 (45 per cent) were combined with cleft palate. Four cases (20 per cent) with cardiac anomalies were also observed. Two fetuses (10 per cent) had abnormal karyotyping (one trisomy 21, one trisomy 18). All fetuses were delivered at or near term. Male deviation was observed in cases with isolated Pierre-Robin sequence or combined mild anomalies (male female ratio: 13:3). Two neonatal mortalities and three with mental retardation were observed. This investigation provides a basis for counselling patients with fetal micrognathia or neonatal Pierre-Robin sequence. The main prenatal sonographic findings of Pierre-Robin sequence are micrognathia, polyhydramnios and cleft palate. In cases of polyhydramnios, sonographic examination of the facial profile and palate are recommended. After the finding of polyhydramnios, micrognathia, and even cleft palate, clinicians should be aware of the possibility of neonatal Pierre-Robin sequence. Cardiac evaluation and karyotyping is also recommended.     

First-trimester nuchal translucency measurement and echocardiography at 16 to 18 weeks of gestation in prenatal detection for trisomy 18

BACKGROUND: Trisomy 18, the second most common autosomal trisomy, has the highest incidence of congenital heart disease of all chromosomal abnormalities. This study assessed the use of nuchal translucency (NT) measurement and fetal echocardiography at 16 to 18 weeks of gestation in prenatal detection for trisomy 18. METHODS: Screening for chromosomal aneuploidy using fetal NT measurement was performed at 10 to 14 weeks of gestation. Detailed fetal echocardiography was performed at 16 to 18 weeks of gestation immediately before genetic amniocentesis for fetal karyotyping in singleton pregnancies with increased fetal NT thickness. RESULTS: Of the 3151 singleton pregnancies included in our study, 171 cases (5.4%) of increased (> or =3.0 mm) NT were noted. Fetal chromosomal abnormalities were identified in 22 (12.9%) of these pregnancies, including 9 with trisomy 21, 5 with trisomy 18, 4 with 45,X and 4 with unbalanced structural abnormalities. Major defects of the heart and the great arteries were identified in 13 (7.6%) of these pregnancies with increased NT. These included eight pregnancies that also had the diagnosis of chromosomal aneuploidy. Among the 22 fetuses with confirmed aneuploidy, all 5 fetuses with trisomy 18, 1 of the 4 fetuses with 45,X and 2 of the 9 fetuses with trisomy 21 had increased fetal NT thickness associated with abnormal fetal echocardiography findings. CONCLUSIONS: Screening for Down syndrome and cardiac defects using first-trimester fetal NT measurement in combination with fetal echocardiography at 16 to 18 weeks of gestation is a feasible and sensitive procedure for the prenatal detection of trisomy 18.     

Sonographic Markers of Fetal Aneuploidy—A Review

The most effective sonographic marker of trisomy 21 and other chromosomal defects is increased nuchal translucency (NT) thickness at 11–14 weeks. Extensive studies over the last decade have examined the methodology of measuring NT, the development of the necessary algorithms for calculating the individual patient risk for trisomy 21 by NT in combination with maternal age and with various maternal serum biochemical markers, and the performance of this test. Another promising marker for trisomy 21, both in the first and second trimesters, is absence of the fetal nasal bone. There is also an extensive literature on the association between chromosomal abnormalities and a wide range of second trimester ultrasound findings. However, there are very few reports that have prospectively examined the screening performance of second trimester markers. This article reviews the association between sonographically detectable fetal abnormalities and chromosomal defects, and examines the value of incorporating these defects in screening policies.     

Cardiac and extra-cardiac anomalies as indicators for trisomies 13 and 18: a prenatal ultrasound study

The purpose of the present study was to establish sonographic markers for prenatal diagnosis of trisomies 13 and 18. Retrospective analysis of sonographic morphology was therefore carried out in seven fetuses with trisomy 13, and 16 fetuses with trisomy 18. Gestational age ranged between 17 and 39 weeks (median 28 weeks). Polyhydramnios and symmetrical growth retardation were present in 14 of 23 fetuses. A cardiac anomaly was diagnosed in all 23 fetuses, the majority representing a ventricular septal defect (n = 8) or double outlet right ventricle (n = 8). Extra-cardiac anomalies were characterized by a high incidence of limb deformities (polydactyly, clenched hands, club feet; n = 15) and omphalocele (n = 7). We conclude that the combined appearance of cardiac and extra-cardiac anomalies should prompt fetal karyotyping. Cardiac anomalies in combination with fetal limb deformities and omphalocele are suspicious for trisomies 13 and 18.     

Pitfalls of gestational age reassignment in evaluation of low maternal serum alpha-fetoprotein levels

Accurate interpretation of low maternal serum alpha-fetoprotein levels depends on confirmation of gestational age by ultrasound. However, revision of gestational age estimations based solely on sonographic fetal biometry may result in excluding the fetus with trisomy from further diagnostic study.