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 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.     

Umbilical cord pseudocyst in trisomy 18

Prenatal diagnosis of cord defects by means of ultrasound examination is possible and highly accurate. Although this is a rare pathological finding, we report two cases in which umbilical cord pseudocysts were associated with trisomy 18. These observations underscore the need of umbilical blood sampling for establishing the karyotype in fetuses with such umbilical cord anomalies and the importance of careful examination of placentas and infants born with such defects.     

Risks of funipuncture in fetuses with single umbilical arteries

OBJECTIVE: To estimate procedure-related risks of funipuncture in fetuses with single umbilical arteries (UAs). METHODS: We identified fetuses that had blood samples collected by funipuncture and in which single UAs were detected, prenatally or postnatally. We also recorded maternal demographics, prenatal sonographic findings, gestational age at the time of the procedure, procedure-related complications, and perinatal outcomes. RESULTS: Over 2 years, 14 fetuses identified as having single UAs had funipuncture for prenatal karyotyping at a median gestational age of 29 weeks (range 20-34 weeks). Each had additional abnormal prenatal sonographic findings. The approach to the cord was transplacental in six cases and transamniotic in eight. There were no failed procedures, and 13 of 14 funipunctures were successful on the first attempt. Three fetuses (21%) had complications (bradycardia in two cases and bleeding in one case), a complication rate not greater than that reported in large series of fetuses that had fetal blood sampling. All three complications were associated with the transamniotic approach. There were no procedure-related pregnancy losses within 2 weeks of the procedure in this series. CONCLUSION: Funipuncture does not seem to be associated with increased risk of procedure-related complications or pregnancy losses in fetuses with single UAs, although the risk could be greater with transamniotic than with transplacental sampling.     

The association of single umbilical artery with cytogenetically abnormal pregnancies

The clinical significance of the absence of one of the two umbilical arteries (single umbilical artery) lies in its association with congenital malformations. Whether this association includes cytogenetic abnormalities is less clear. A retrospective review of all detected chromosomally abnormal pregnancies at the University of Maryland was carried out. Of 109 cytogenetically abnormal pregnancies, the number of umbilical cord vessels could be documented in 53 cases. Six (11.3%) had a single umbilical artery. A single umbilical artery was noted in two of nine fetuses (22.2%) with trisomy 18 and in two of six fetuses (33.3%) with trisomy 13. Two other unusual chromosomal constitutions were noted in cases of a single umbilical artery. None of the 11 fetuses with sex chromosome abnormalities (including eight with monosomy X) had a single umbilical artery. Of 18 fetuses with trisomy 21, none had a single umbilical artery. This study suggests that a single umbilical artery is preferentially associated with certain karyotypic abnormalities and that trisomy 21 does not appear to be associated with a single umbilical artery.     

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。     

产前超声诊断在胎儿左侧异构中的应用

目的:探讨胎儿左侧异构的产前超声征象及其诊断价值。方法:回顾分析21例产前诊断为胎儿左侧异构的病例资料,对比总结其超声征象与随访结果。结果:21例左侧异构胎儿中,内脏心脏异位16例,先天性心脏病19例(伴心脏传导阻滞5例),下腔静脉离断伴奇静脉异常连接19例,其中两种及两种以上异常诊断胎儿左侧异构的敏感性为90.5%。染色体异常3例,18三体2例,13三体1例。18例终止妊娠,1例胎死宫内,2例存活。结论:产前超声诊断胎儿左侧异构是可行的,重要超声征象是内脏心脏异位、先天性心脏病伴或不伴心脏传导阻滞、下腔静脉离断伴奇静脉异常连接,出现上述两种或两种以上异常可提高该病的诊断敏感性。     

Dandy-Walker syndrome: a review of fifteen cases evaluated by prenatal sonography

Fifteen cases of the Dandy-Walker syndrome evaluated by prenatal sonography were reviewed retrospectively. A posterior fossa cyst communicating with the fourth ventricle was a feature in each case. Hydrocephalus was present in 53% of fetuses. Extracranial congenital malformations were documented in 60% of cases. Cardiac, genitourinary, gastrointestinal, and skeletal anomalies were noted. Of 12 available karyotypes, 4 (33%) were abnormal, including two cases of trisomy 18. Excluding terminated pregnancies, there was an overall mortality of 55%. Associated congenital defects contributed to 83% of the postnatal deaths. The Dandy-Walker syndrome can be accurately diagnosed in utero by sonographic demonstration of characteristic morphologic changes in the fetal posterior fossa. The prenatal examination should include an evaluation of associated supratentorial and extracranial defects. Coexisting structural and chromosomal anomalies occur frequently and adversely affect survival.     

Single umbilical artery and its siding in the second trimester of pregnancy: relation to chromosomal defects

OBJECTIVES: To determine the possible association between single umbilical artery (SUA) in the second trimester of pregnancy and the incidence of chromosomal abnormalities. To determine whether the presence of chromosomal defects in fetuses with SUA is related to the side of the missing artery. METHODS: Color flow imaging of the fetal pelvis was used to determine the number of umbilical arteries in 2147 fetuses immediately before amniocentesis for karyotyping in the second trimester of pregnancy. RESULTS: SUA was diagnosed in 102/2147 (4.8%) cases. The left umbilical artery was absent in 60/102 (58.8%) fetuses, compared with the 42/102 (41.2%) for the right artery. The rate of chromosome abnormalities was significantly higher among fetuses with SUA than among those with 2 umbilical arteries (19/102 or 18.6% versus 109/2045 or 5.3%; OR = 4.1, 95% CI 2.3-7.1, p < 0.0001). Among fetuses with SUA, there was no significant difference in the rate of chromosome abnormalities between those with absence of the left versus the right artery (11/60 or 18.3% versus 8/42 or 19.0%, p = 0.93). There was an SUA in 5/39 (12.8%) cases with trisomy 21, 8/16 (50%) with trisomy 18, 1/4 (25%) with trisomy 13 and 5/69 (7.2%) with other chromosomal defects. There were no chromosome abnormalities in fetuses where a single umbilical artery was an isolated sonographic finding. All fetuses with SUA and chromosomal defects had associated abnormalities detected by ultrasound. CONCLUSION: A single umbilical artery (SUA) in the second trimester of pregnancy has a high association with trisomy 18, 13, 21 and other chromosomal defects, but all chromosomally abnormal fetuses had associated malformations detected by ultrasound. The absence of the left artery is more frequent than the absence of the right artery. The association with chromosomal abnormalities seems to be equal on each side.     

Subamniotic hematoma: 3D and color Doppler imaging in the differential diagnosis of placental masses and fetal outcome

The aim of this study was to evaluate the role of 3D and color Doppler (CD) imaging in prenatal diagnosis and management of placental subamniotic hematoma and to speculate about the prenatal diagnosis of the solid and cystic placental masses protruding from the fetal surface of the placenta. Five pregnancies in which a large mass was seen protruding from the fetal surface of the placenta were studied in the period between January 2006 and January 2008. 3D and color flow imaging were settled in order to monitor the sonographic features of the mass during pregnancy, to evaluate the continuity of the solid portion of the mass with the fetal placental surface and to detect the blood flow signals within the mass. This study reports the clinical outcome and the histologic findings of five cases of subamniotic hematomas detected in the course of prenatal ultrasound examinations between January 2006 and January 2008. Sonographic features of the mass protruding from the chorionic plate show a consistence typical of a solid mass, in the recent subamniotic hematoma, or a predominantly cystic mass in the chronic subamniotic hematoma. Neither adverse clinical correlations nor structural nor chromosomal fetal abnormalities were found after delivery. The joint and the continuity of the solid portion of the mass with the fetal placental surface were correctly identified by prenatal ultrasound 3D examination. The CD imaging was conclusive in order to detect the absence of blood flow within the solid part of these masses. In conclusion prenatal sonographic features in recent subamniotic hematomas include the detection of a complex structure overlying the fetal plate of the placenta next to the cord insertion, covered by a thin membrane (the amnion), containing a predominantly solid mass arising from the chorionic plate. Differential diagnosis has to be done between recent subamniotic hematoma and placental chorioangioma by the use of color flow imaging: it displays blood flow within the mass in the case of chorioangioma, and conversely demonstrates the lack of color flow signals in the hematoma. The 3D imaging is conclusive in order to identify the continuity of the solid mass with the fetal placental surface. The chronic subamniotic hematomas are predominantly cystic structures in which there is a solid component attached to the fetal surface of placenta, representing a retracted clot and/or a fibrin deposit, underlying the hematoma. The main differential diagnosis in the case of a cystic mass overlying the fetal plate of the placenta, covered by a thin membrane, during the ultrasound examination, is between a placental cyst and a large pseudocysts of the umbilical cord at the placental insertion. In the case of a pseudocyst, the transonic formation is clear and lacks of a solid mass within. The correct differential diagnosis between subamniotic hematoma and the pseudocysts of the umbilical cord is required because of the association between chromosomal anomalies and pseudocysts.     

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.     

Antenatal sonographic detection of single umbilical artery.

The absence of one umbilical artery of single umbilical artery (SUA) is one of the most common congenital malformations in man. This vascular anomaly of the umbilical cord is frequently associated with other congenital malformations as well as some adverse perinatal events such as intrauterine growth retardation (IUGR), premature delivery, and increased perinatal mortality. Five cases of SUA detected prenatally by ultrasound are reported here in detail, including the first reported case in a twin gestation. None of the 5 affected infants had associated anomalies, but 2 cases of intrauterine growth retardation (IUGR) and 1 stillborn infant were noted in this series. An umbilical vein/umbilical artery ratio less than 2 was invariably found in all cases, making this observation another useful sonographic characteristic to use in the antenatal detection of SUA. Since the umbilical cord can be easily seen prenatally by ultrasound, and SUA is recognized as an important index for detecting congenital malformations, examination of the umbilical cord for the absence of one umbilical artery is an extremely valuable tool in prenatal diagnosis. The prenatal detection of SUA demands an extensive search for associated anomalies and a close surveillance of fetal well-being, since these fetuses have a high risk of fetal death or IUGR. Sonologists and sonographers should be aware of the possibility of SUA, especially in those cases associated with congenital malformations or IUGR.     

Fetal nuchal cystic hygromata: associated malformations and chromosomal defects.

During a 6-year period (1985-1990), blood karyotyping was performed in 44 fetuses with septated, bilateral, dorsal, cervical cystic hygromata. This condition constitutes a different entity from nuchal oedema. There were 33 (75%) chromosomal abnormalities, including Turner's syndrome (n = 31), trisomy 18 (n = 1) and trisomy 21 (n = 1). Congenital heart defects (CHD), mainly coarctation of the aorta, were present in 15 of the fetuses with Turner's and in 1 of the chromosomally normal fetuses. The incidence of CHD was higher in the fetuses with ultrasonographic evidence of moderate/severe hydrops (41%; 13 of 32 cases) than in those with mild or no hydrops (25%; 3 of 12 cases). Although both the biparietal diameter (BPD) and femur length (FL) were reduced in all fetuses, the FL to BPD ratio was below the 5th percentile in 29 of the 33 (88%) chromosomally abnormal fetuses, but in only 4 of the 11 (36%) chromosomally normal ones. In the chromosomally normal group, 3 of the fetuses had multiple pterygium syndromes, and in such cases the risk of recurrence may be high. In contrast, in the group of mutant chromosomal disorders with monosomy or trisomy, the risk of recurrence is in the order of 1%.     

Cystic fibrosis and chromosome abnormalities associated with echogenic fetal bowel.

OBJECTIVE: To determine the prevalence of cystic fibrosis mutations and chromosome abnormalities in the fetuses of a heterogeneous population of pregnant women referred for prenatal testing for echogenic fetal bowel. METHODS: Fetal or parental samples obtained after a second-trimester sonographic finding of echogenic fetal bowel were submitted to a referral diagnostic laboratory during a 2-year period. Results of DNA testing and karyotyping on these samples were analyzed to determine the prevalence of cystic fibrosis transmembrane reductase gene mutations and chromosome abnormalities. RESULTS: Of 244 cases tested, two fetuses were positive for two cystic fibrosis mutations. This rate (0.8% or two of 244) is 20 times higher than the general white population rate of one per 2500. In a third case, both parents were carriers but the fetus was not tested. Nine (8%) of 113 fetuses tested had one cystic fibrosis mutation. Of 106 fetuses for whom chromosome results were available, three (2.8%) fetuses had a chromosomal abnormality: two had trisomy 21 and one had Klinefelter syndrome. A fourth fetus carried a de novo, apparently balanced, 5;12 translocation. CONCLUSION: These laboratory results are representative of a broad spectrum of clinical settings and indicate a generalized increased risk associated with this sonographic finding. Therefore, when a second-trimester sonographic diagnosis of fetal echogenic bowel is made, fetal testing for both cystic fibrosis and chromosome abnormalities is warranted.     

产前超声诊断单脐动脉与胎儿异常的相关性研究

目的探讨超声检测胎儿脐带血管数目预测胎儿先天异常的价值。方法2000年1月至2006年10月在中山大学附属第一医院采用超声检测胎儿脐血管数目，对单脐动脉胎儿行产前超声系统筛查及胎儿染色体检查；分析单脐动脉合并畸形类型，与染色体异常的关系及胎儿结局。结果产前超声诊断胎儿单脐动脉119例，包括左侧72例（60．5％），右侧47例（39．5％）。单纯性单脐动脉59例（49.6％）；合并其他结构畸形60例（50．4％），其中泌尿系统畸形25例（41．7％），心血管系统畸形17例（28.3％），中枢神经系统畸形15例（25.0％），下肢畸形9例（15．0％），前腹壁和消化道畸形各5例（各占8．3％），唇裂或唇腭裂畸形3例（5．0％），其他畸形3例（5．0％）。行胎儿染色体检查41例，发现染色体异常8例，包括18-三体综合征3例、13-三体综合征1例、21．三体综合征1例、染色体片段异常3例，均合并其他畸形。结论胎儿单脐动脉左侧发生率高于右侧，约50％合并其他畸形；合并畸形时，染色体异常发生率较高；大部分单纯性单脐动脉胎儿结局良好。     

Umbilical cord pseudocyst in a fetus with trisomy 18

An umbilical cord pseudocyst was detected in the 28th week of gestation in a fetus complicated with growth restriction and polyhydramnios. The combination of cord pseudocysts, growth restriction, and polyhydramnios prompted us to perform a detailed ultrasonographic examination (gray scale and three-dimensional), which revealed the presence of micrognathia, overlapping fingers, and congenital heart defects, features characteristic of trisomy 18. Karyotyping confirmed a diagnosis of trisomy 18. After spontaneous labor onset, the infant was delivered at 31 weeks of gestation, and died soon after delivery. An umbilical cord pseudocyst is a good marker for the prenatal detection of trisomy 18.     

Fetal cystic hygromata: insights gained from fetal blood sampling

Twelve second-trimester fetuses with cystic hygroma underwent fetal blood sampling for rapid karyotyping, haematologic evaluation, and blood gas analysis. An abnormal karyotype was found in seven cases: monosomy X in five, trisomy 21 in one, and trisomy 13 in the other. Eight of ten fetuses undergoing blood gas analysis showed hypoxaemia, five of which were growth-retarded. Nine pregnancies were terminated. Of the remaining three, only one fetus survived the perinatal period.     

Anomalies of the fetal venous system: a report of 26 cases and review of the literature

OBJECTIVE: To evaluate sonographic appearance, natural history, and neonatal outcome of fetal venous anomalies. METHODS: We performed an observational study, including all fetuses affected by abnormalities of the venous system diagnosed by ultrasound during the prenatal period. RESULTS: 26 fetuses were identified. Other malformations were present in 5 cases (19.2%), 1 fetus had trisomy 21, and 1 fetus had intrauterine growth retardation (IUGR). Twenty-five pregnancies ended in liveborn infants, and there was 1 case of unexplained intrauterine death in the fetus with IUGR affected by varix of the umbilical vein. CONCLUSIONS: Fetal venous anomalies are very rare and may be associated with fetal malformations or IUGR. Conservative management appears to be an adequate medical practice in the absence of other fetal problems, but in the presence of a varix of the umbilical vein, serial follow-up scans are needed to exclude the onset of hydrops or thrombosis of the varix.     

Evidence for blood chimerism in dizygotic spontaneous twin pregnancy discordant for Down syndrome

BACKGROUND: A monochorionic-diamniotic placenta (MCDAP) is rare in dizygotic (DZ) twinning. All reported cases have been documented in pregnancies achieved by the induction of ovulation alone or during the IVF cycle. METHODS AND RESULTS: We report a spontaneous pregnancy in a 39-year-old patient with evidence of MCDAP in DZ twins, discordant for trisomy 21. The first and second-trimester sonographic scans indicated male twins with MCDAP. Amniocentesis, performed because of advanced maternal age, revealed a normal karyotype in one fetus, and trisomy 21 in the other. Molecular studies, performed in order to confirm the zygosity and chorionicity, demonstrated that the fetuses were DZ. In order to identity the affected twin, a detailed sonographic examination was repeated, but no abnormal findings associated with Down syndrome were demonstrated in any of the fetuses. Therefore, umbilical cord blood samples were obtained from both fetuses. Chromosomal analysis revealed in both fetuses two cell lines: a normal cell line of 46,XY and a 47,XY,+ 21 cell line, in 65 and 80% of the cells, respectively. This result was independently confirmed by both FISH and G-banding. DNA extracted from both cord blood samples demonstrated an admixture of two distinct genotypes in each sample. CONCLUSIONS: We propose that this case represents a monochorionic-dizygotic twin pregnancy with blood chimerism. The most plausible mechanism underlying this phenomenon is placental fusion early in pregnancy, resulting in an architecturally single placenta originating from two distinct zygotes. The newly formed blood vessels created anastomoses between the DZ twins and allowed reciprocal blood chimerism between the normal and the trisomic twin.