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.     

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.     

Ultrasound findings in trisomy 22

We sought to identify the characteristic sonographic findings of fetal trisomy 22 by performing a retrospective review of nine cases of fetal trisomy 22. All cases of chromosomal mosaicism were excluded, as were first-trimester losses. Indications for sonography, gestational age, and sonographically detected fetal anomalies were analyzed. The majority of patients were referred for advanced maternal age or abnormal ultrasound findings on screening exam. Oligohydramnios was the most common sonographic finding, present in 55% of affected fetuses. Intrauterine growth restriction and increased nuchal thickness were slightly less frequent.     

Sonographic measurement of the fetal iliac angle in trisomy 21, 18 and 13

OBJECTIVE: To determine whether iliac wing angle measurement in second trimester fetuses is a useful sonographic marker for the detection of trisomy 21, 18 and 13. METHODS: During the period between September 1998 and September 2001, 406 fetal iliac angle measurements were performed in women in the second trimester of their pregnancies. The iliac angle measurements in fetuses with trisomy 21 (n = 25), trisomy 18 (n = 10) and trisomy 13 (n = 5) were compared with iliac angle measurement in fetuses with normal karyotypes (n = 333). RESULTS: The mean iliac wing angle in the fetuses with trisomy 21 was 92.67 and 79.35 degrees and 74 degrees in fetuses with trisomy 18 and 13 (the mean iliac wing angle in the healthy fetuses was 70.09 degrees ). CONCLUSION: The proven larger iliac wing angle in neonates with Down's syndrome can be demonstrated sonographically during the pregnancy, especially during the second trimester, and may be useful in prenatal screening of trisomy 21. The sonographic measurement of the fetal iliac angle cannot be used as a marker for trisomy 18 and 13. We have shown that fetuses with trisomy 18 and 13, on average, have iliac angles only a few degrees larger than healthy fetuses.     

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.     

247例妊娠中期孕妇羊水细胞染色体核型分析

目的 分析妊娠中期进行产前诊断的孕妇羊水细胞染色体核型，了解此期异常核型发生的频率、类型及与各种产前诊断指征的关系。方法 对247例妊娠中期孕妇行羊膜腔穿刺术抽羊水作羊水细胞培养检查染色体核型。结果 发现异常核型14例，异常核型出现频率为5．67％，其中三体型7例，占异常核型的50％，分别为21三体4例，18三体2例，13三体1例；其次为平衡易位6例，占42．86％。高龄孕妇中21三体检出率为5．56％(1／18)，非高龄组为1．31％(3／229)，P=0．235，差异无显著性。15例产前常规B超检查发现胎儿发育异常的孕妇中，检出三体儿3例。结论 在有各种产前诊断指征的妊娠中期孕妇中，胎儿染色体异常发生率为5．67％，染色体三体为主要的异常核型。孕中期B超检查做为产前常规筛查可提高胎儿染色体异常的检出率。     

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 diagnosis of complete trisomy 9: a case report and review of the literature

Complete trisomy 9 is a very rare chromosome aneuploidy, associated with specific patterns of multisystem dysmorphism and a wide spectrum of congenital anomalies. We present a case of complete trisomy 9 with prenatal sonographic findings in the second trimester. The combination of sonography and karyotyping from cordocentesis enabled us to establish the prenatal diagnosis. An additional clinical feature of this syndrome that has not been reported previously is an aortopulmonary communication. A review of the literature specifically dealing with prenatal sonographic findings with complete trisomy 9 is also presented.     

Trisomy 21. Second-trimester ultrasound

Not every aspect of sonographic examination reveals karyotypic abnormalities. Ultrasound examination of a fetus with trisomy 21 generally reveals normal amniotic fluid, normal placentation, and normal fetal growth. In addition, other chromosomal abnormalities have many of the same sonographic findings as Down syndrome, and many findings have a large overlap with phenotypically normal fetuses. The importance of second-trimester ultrasound screening for Down syndrome has remained great because of its ease of use and relative effectiveness. Trained sonographers can adjust the relative risk for trisomy 21 and alter the need for genetic amniocentesis. It is important that parents understand the limitations of a screening test and the risks and benefits of possible subsequent confirmatory testing. If a major structural abnormality is identified on ultrasound, karyotype determination should be considered. Nuchal thickness in the first or second trimester remains the most clinically useful marker for trisomy 21. The predictive value of all the markers depends on the population studied and can be modified by a host of biochemical markers and historical factors. If fetal karyotype analysis could be performed without sampling through the uterus, prenatal diagnosis could be offered to all pregnant women, and screening would be unnecessary. Despite its limitations, ultrasound will have an important role in prenatal diagnosis at least until isolating and testing fetal cells from maternal blood or other sources becomes practical and widely available. Whether used alone or in conjunction with additional biochemical or molecular serum markers, ultrasound is an important and powerful tool in prenatal genetic evaluation.     

Endovaginal sonographic diagnosis of the fetal urinary tract anomalies in early pregnancy

Transvaginal sonography has enhanced the ability to follow fetal development and detect pathologies in early gestation. Examination of the fetal urinary tract is an integral part of routine sonographic examinations in the second trimester of pregnancy and one of the major benefits of prenatal sonography is to allow early diagnosis of relatively common urinary tract malformations. Detailed evaluation of the fetal urinary tract and identification of anomalies were considered to be difficult before the 18th week of gestation prior to the use of transvaginal sonography. Using the transvaginal route, a detailed evaluation of the kidneys is possible around 12 weeks and structural anomalies of the urinary tract are being detected at an ever-increasing rate. Transvaginal sonography, owing to its proximity to the maternal pelvic organs, allows an earlier determination of the normal fetal urinary system and more accurate diagnosis and identification of fetal urinary anomalies as compared with transabdominal ultrasound. Received: 22 May 2000 / Accepted: 21 August 2000     

Pseudocyst of the umbilical cord: prenatal sonographic appearance and clinical significance

OBJECTIVE: To assess the clinical significance of umbilical cord pseudocysts detected prenatally by sonography. METHODS: The prenatal sonographic findings, karyotype, and perinatal outcome in 13 fetuses with umbilical cord pseudocysts were reviewed retrospectively. RESULTS: Umbilical cord pseudocysts were diagnosed at a median gestation of 27 weeks (range 15-37). Pseudocysts were single in eight cases with cyst diameters ranging from 20 to 50 mm, and double in one case. In the remaining four cases, multiple small cystic masses measuring less than 8 mm were identified. Additional sonographic findings were noted in 11 cases; ten of these fetuses had prenatal karyotyping, which showed trisomy 18 in five cases, trisomy 13 in one case, and a 46,XX, inv ins(18;21) complement in one case. Among the seven chromosomally abnormal fetuses, umbilical cord pseudocysts were multiple in four fetuses and single in three. All chromosomally abnormal fetuses and two euploid fetuses with associated structural defects died in utero or in the neonatal period. There were no perinatal complications in either of the fetuses with isolated pseudocysts. CONCLUSION: The prenatal sonographic appearance of umbilical cord pseudocysts varied widely. These umbilical cord cystic masses were associated strongly with chromosomal disorders and structural defects, regardless of their sonographic appearance in utero.     

The role of fetal echocardiography in the prenatal diagnosis of aneuploidy based upon prenatally diagnosed patau syndrome fetuses (case analysis)

OBJECTIVE: Assessment of usefulness of the fetal echocardiography and genetic sonography in prenatal diagnosis trisomy 13 (retrospective analysis). MATERIAL AND METHOD: Between 1994-1999 at the Department for Diagnosis of Congenital Malformation at the Institute of PPMH in 11 fetuses with Patau Syndrome ultrasound and echocardiography examination were performed. In our study the most of cases come from low risk of pregnant women. RESULTS: Fetal heart defect was the most common anomaly diagnosed prenatally in fetuses with Patau Syndrome (7/11), the second one were central nervous system anomalies (6/11) and genitourinary system anomalies (6/11).     

Correlation of ultrasound findings and biochemical markers in the second trimester of pregnancy in fetuses with trisomy 21

OBJECTIVE: The aim of the present study was to assess possible correlations between ultrasound findings and maternal serum biochemical ('triple test') markers among fetuses with trisomy 21 in the second trimester of pregnancy. METHODS: The study was a retrospective cohort study of 72 pregnancies affected by trisomy 21 who had a second trimester ultrasound and biochemical screen performed at a single center between 1990 and 1999. The biochemical screen consisted of alpha-fetoprotein (AFP), total beta human chorionic gonadotrophin (hCG) and estriol (uE(3)). Marker levels were expressed in multiples of the median (MoM). The ultrasound findings assessed were major structural anomalies, short humerus length, short femur length, increased nuchal fold thickness (NF), hyperechoic bowel, echogenic intracardiac focus (EIF), ventriculomegaly, choroid plexus cysts and renal pyelectasis. RESULTS: Second trimester maternal serum biochemical markers and ultrasound findings appeared to be largely independent of each other. However, some significant correlations were observed. Estriol was significantly lower when a fetal cystic hygroma was detected on ultrasound compared to those with no cystic hygroma (0.40 vs. 0.70 MoM, p<0.05). The median hCG level was significantly lower in those pregnancies with a normal second trimester fetal ultrasound compared to those with positive ultrasound findings (2.07 vs. 2.87 MoM, p<0.05). Median hCG levels were also significantly higher in those cases with NF> or =5 mm as compared to those with NF<5 mm (2.99 vs. 2.49 MoM, p<0.05). This difference persisted after exclusion of the five cases with cystic hygromas (2.99 vs. 2.49 MoM, p<0.05). A significant positive correlation was observed between log(10) hCG and log(10) NF MoM (Spearman's rho=0.252, p<0.05). NF was significantly greater among fetuses with an identifiable cardiac defect compared with those without a detectable cardiac defect (median of 7.0 mm vs. 3.8 mm, p<0.01). This difference persisted when expressed as multiples of the median (2.8 vs. 1.3 MoM, p<0.01). CONCLUSION: Second trimester ultrasound and biochemical markers are largely independent in fetuses with trisomy 21, however significant correlations between the two were observed in the present series. These may be important in screening protocols that combine second trimester ultrasound and biochemical markers.     

Nuchal translucency and other first-trimester sonographic markers of chromosomal abnormalities

There is extensive evidence that effective screening for major chromosomal abnormalities can be provided in the first trimester of pregnancy. Prospective studies in a total of 200,868 pregnancies, including 871 fetuses with trisomy 21, have demonstrated that increased nuchal translucency can identify 76.8% of fetuses with trisomy 21, which represents a false-positive rate of 4.2%. When fetal nuchal translucency was combined with maternal serum free-beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A in prospective studies in a total of 44,613 pregnancies, including 215 fetuses with trisomy 21, the detection rate was 87.0% for a false-positive rate of 5.0%. Studies from specialist centers with 15,822 pregnancies, which included 397 fetuses with trisomy 21, have demonstrated that the absence of the nasal bone can identify 69.0% of trisomy 21 fetuses, which represents a false-positive rate of 1.4%. It has been estimated that first-trimester screening by a combination of sonography and maternal serum testing can identify 97% of trisomy 21 fetuses, which represents a false-positive rate of 5%, or that the detection rate can be 91%, which represents a false-positive rate of 0.5%. In addition to increased nuchal translucency, important sonographic markers for chromosomal abnormalities, include fetal growth restriction, tachycardia, abnormal flow in the ductus venosus, megacystis, exomphalos and single umbilical artery. Most pregnant women prefer screening in the first, rather than in the second, trimester. As with all aspects of good clinical practice, those care givers who perform first-trimester screening should be trained appropriately, and their results should be subjected to external quality assurance.     

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.     

The utility of detailed first trimester ultrasound examination in abnormal fetal nuchal translucency

OBJECTIVE: To determine the value of a first trimester fetal ultrasound examination in cases of an increased nuchal translucency (NT). METHOD: A detailed fetal ultrasound examination was performed within 4 days of a detection of a first trimester increased NT. RESULTS: As many as 23 fetuses were evaluated. Severe anomalies were detected in eight and mild anomalies were detected in six fetuses. Two fetuses had trisomy 13, one had trisomy 21, and 16 fetuses had a normal karyotype. A chromosomal analysis was not available in four fetuses with major anomalies due to parental decision. In one fetus, craniosynostosis was detected only at 24 weeks' gestation. CONCLUSIONS: The current study shows that a first trimester targeted scan of fetuses with an increased NT in an experienced center can shorten the parental decision-making process and spare parents a prolonged period of diagnostic uncertainty and anxiety, particularly when a structural anomaly is clearly diagnosed in the first trimester.     

Measurement of nuchal translucency as a single strategy in trisomy 21 screening: should we use any other marker?

OBJECTIVE: To evaluate the role of nuchal translucency thickness as a single marker in screening for trisomy 21 at 10-16 weeks' gestation. METHODS: From December 1996 to October 2001, nuchal translucency was measured in 11,281 consecutive early second trimester fetuses referred to our unit for prenatal care and delivery. Scans were performed by eight experienced ultrasonographers, under strict methodological criteria. RESULTS: Chromosomal abnormalities were found in 118 cases (52 trisomy 21). Using nuchal translucency greater than the 95th centile as a cut-off, the overall detection rate was 71.2% with a specificity of 95.4%, and a positive predictive value of 14%. In the trisomy 21 selected group, detection rate, specificity, and positive predictive value for nuchal translucency were 92.3%, 95.4%, and 8.5%, respectively. The detection rate of trisomy 21 reached 100% when nuchal translucency was measured between 10 and 14 weeks' gestation, maintaining the same specificity. CONCLUSION: Early second trimester nuchal translucency measurement can achieve prenatal detection rates of trisomy 21 greater than 95% with a 5% false-positive rate. With a detection rate so high, the benefits of using additional markers may be less than previously considered. Although maternal age, other sonographic or Doppler markers, and maternal serum biochemistry might play a role in prenatal strategies to detect fetal chromosomal abnormalities, the high detection rate of trisomy 21 fetuses using nuchal translucency as a single parameter suggests that early nuchal translucency measurement between 10 and 14 weeks' gestation can be a simple screening strategy for this condition.     

Prospective ranking of the sonographic markers for aneuploidy: data of 2143 prenatal cytogenetic diagnoses referred for abnormalities on ultrasound

OBJECTIVE: To design a scheme to rank sonographic anomalies as indicators of aneuploidy and record the distribution of data from 2143 prenatal amniotic fluid/chorionic villous sample diagnoses referred for karyotyping because of fetal anomalies detected with ultrasound. METHODS: In all cases the records of sonographic anomalies were obtained prior to karyotyping. A cascade of seven prospective categories of ultrasound anomalies was chosen and the data were included in the highest compatible sonography category. The categories were in descending order: (I) combined central nervous system (CNS)/cranial shape and cardiac anomalies (excluding spina bifida and anencephaly); (II) key anomaly present (exomphalos/ intrauterine growth restriction/duodenal atresia/cystic hygroma/fetal hydrops/talipes--with other multiple anomalies); (III) CNS +/- other abnormality (excluding choroid plexus cyst, spina bifida, anencephaly); (IVa) increased nuchal translucency--first trimester +/- other abnormality; (IVb) increased nuchal thickening--second trimester +/- other abnormality; (V) cardiac anomaly +/- other abnormality; (VI) other markers of aneuploidy (pyelectasis/two vessel cord/echogenic bowel/short femur); and (VII) other (mostly isolated) malformations. RESULTS: There were 412/2143 (19.2%) chromosome abnormalities detected in this sonographically abnormal group. Overall, the prevalence of aneuploidy significantly ranged from 51 to 3% according to the above I-VII ultrasound categories and from approximately 1-80% for individual ultrasound anomalies. Likelihood ratios were derived for many ultrasound anomalies for several aneuploidy groups: trisomies of 13; 18; and 21; 45,X and 45,X mosaics; triploidy; other autosomal duplications and/or deletions; and other (than 45,X) sex chromosomal aneuploidies. CONCLUSION: It is suggested this data could be used to assist pre-procedural counselling of patients after the ultrasound scan in tertiary referral centres for prenatal cytogenetic diagnosis.     

The value of sonography in early pregnancy for the detection of fetal abnormalities in an unselected population.

OBJECTIVE: To determine the value of early pregnancy sonography in detecting fetal abnormalities in an unselected obstetric population. DESIGN Prospective cross-sectional study. All women initially underwent transabdominal sonography and when the anatomical survey was considered to be incomplete, transvaginal sonography was also performed (20.1%). Nuchal translucency was measured and karyotyping was performed as appropriate. SETTING: University Department of Obstetrics and Gynaecology. PARTICIPANTS: 6634 sequential unselected women (mean maternal age 29.9 years, range 13-50; mean gestational age 12+4 weeks, range 11+0-14+6), carrying 6443 live fetuses participated in this study. MAIN OUTCOME MEASURE: Detection rate of fetal anomalies and the associated cost per case detected in early pregnancy. RESULTS: The incidence of anomalous fetuses was 1.4% (92/6443) including 43 chromosomal abnormalities. The detection rate for structural abnormalities was 59.0% (37/63, 95% CI 46.5-72.4) and the specificity was 99.9% in early pregnancy. When the first and second trimester scans were combined, the detection for structural abnormalities was 81.0% (51/63, 95% CI 67.7-89.2). Seventy-eight percent (31/40) of chromosomal abnormalities (excluding three cases of XXY) were diagnosed at 11-14 weeks, either because of a nuchal translucency greater than or equal to the 99th centile for gestational age (43%; 17/40, 95% CI 27.4-60.4), or due to the presence of structural abnormalities (35%; 14/40, 95% CI 21.2-52.8). Sixty-five percent (15/23) of cases of trisomy 21 were also diagnosed either because of having a nuchal translucency greater than or equal to the 99th centile (57.0%; 13/23) or due to the presence of a structural abnormality (9.0%; 2/23). Overall, the detection rate of structurally abnormal fetuses was 59% (37/63) in early pregnancy and 81% in combination with the second trimester scan. The cost per abnormality diagnosed in early pregnancy is estimated to be pound sterling 6258 per structurally abnormal fetus, pound sterling 7470 per chromosomal abnormality and pound sterling 4453 per anomalous fetus. CONCLUSION: The majority of fetal structural and chromosomal abnormalities can be detected by sonographic screening at 11-14 weeks, but the second trimester scan should not be abandoned.