Prenatal diagnosis for paediatricians

In Ontario, approximately 140,000 women deliver newborn infants each year. Of these women, 60,000 to 70,000 have multiple marker screening, 10,000 undergo amniocentesis or chorion villus sampling and virtually all have at least one prenatal ultrasound. Multiple marker screening is not used in every province and territory; however, amniocentesis and prenatal ultrasound are used throughout Canada. Most paediatric patients will have been exposed to some form of prenatal diagnosis. If an abnormality is found prenatally, parents may have concerns to discuss with the paediatrician after the child is born. Likewise, if a child with a problem is born following a normal pregnancy, the parents will want to know why the problem was missed prenatally. Paediatricians should be aware of prenatal tests that have been performed to understand better their patients and their families.     

Invasive antenatal procedures and requirement for neonatal intensive care unit admission

Neonatal respiratory difficulties are increased following second trimester amniocentesis. In preterm, prolonged rupture of the membranes, respiratory outcome is particularly poor when rupture occurs in the first trimester. It therefore seems likely that first trimester/early amniocentesis (EA) would be associated with severe respiratory problems necessitating a high neonatal intensive care unit (NICU) admission rate. To test that hypothesis, the requirement for admission to the NICU of 278 infants whose mothers had undergone EA, 262 whose mothers had undergone chorion villus sampling (CVS group) and 264 controls whose mothers had undergone no invasive procedures were reviewed as were their diagnoses if they needed admission. There was no significant difference in the mode of delivery, gestational age or gender distribution of the three groups and the median maternal age of the EA and CVS groups was similar. Nineteen EA, eight CVS and five control infants required admission to the NICU (EA versus controls, P < 0.01; EA versus CVS plus controls, P < 0.005). Nine EA, one CVS and four control infants had suffered respiratory problems (EA versus CVS P < 0.05). Logistic regression analysis demonstrated that immaturity and EA were significantly associated with a requirement for NICU admission. We conclude infants whose mothers have undergone EA may be at increased risk for NICU admission, this is partly due to respiratory problems but the association is uncommon. Received: 1 August 1996 / Accepted: 12 December 1996     

Resultados perinatales tras prueba diagnóstica invasiva en el embarazo

IntroductionInvasive prenatal diagnostic techniques allow us to conduct genetic tests. The development of non-invasive techniques has reduced their use. The foetal loss rate following an invasive procedure is considered to be around 1%. The published data is heterogeneous however, although everything indicates that the risk has been overestimated, we need to conduct further studies.Material and methodsIn our single-centre retrospective study we analysed the procedures carried out using invasive prenatal diagnostic techniques between 2011 and 2019. A total of 832 invasive techniques were performed. Perinatal results are compared with a control group of pregnant women (n = 1734).ResultsThe early foetal loss rate for the different techniques were 1.1% for amniocentesis, 1.6% for transvaginal chorionic biopsy and 5% for abdominal chorionic biopsy, with a total rate of 1.1%, without statistically significant differences between them (P = .57). We found differences in foetal outcome, in terms of variable early foetal loss, related to the attempts made (when three attempts were made, the risk increased). When comparing the perinatal outcomes after delivery of the group that underwent techniques with the control group, a higher rate of caesarean sections was found in the study group (28.9% vs 20.5%), in addition to lower mean gestational age at delivery (38.33 vs. 38.95 weeks).DiscussionWhen the invasive technique is performed at the right time and with no more than two attempts, we consider that the risk of foetal loss is not affected, and is equal to that of the general population.     

2226例地贫羊水产前诊断分析

目的探讨羊水产前诊断在检测中、重型地中海贫血胎儿中的应用,以此降低出生缺陷。方法应用跨越断裂点PCR（Gap-PCR）法以及反向点杂交技术（RDB-PCR）,对2226例孕妇羊水进行产前地贫基因检测。结果检测出正常胎）L575例占比例25．8％,异常胎儿165l例占比例74．2％。其中Bart‘S水肿胎137例,血红蛋白H病180例,中、重型β-地贫96例,中、重型α复合β地贫46例。结论高危人群在孕中期行羊水产前诊断可以有效地阻止中、重型地贫患儿的出生,从而降低出生缺陷。     

无创产前检测技术筛查胎儿性染色体非整倍体的临床价值

目的探讨无创产前检测(NIPT)在胎儿性染色体非整倍体(SCA)筛查中的临床价值。方法选择2018年4月至2019年9月,在徐州市妇幼保健院进行NIPT筛查的7144例单胎妊娠孕妇为研究对象。采集孕妇外周血5 mL进行全基因组大规模平行测序,预测发生胎儿SCA的风险值。再对NIPT提示胎儿SCA孕妇,进一步进行羊水穿刺术产前诊断。本研究遵循的程序符合徐州市妇幼保健院伦理委员会所制定的伦理学标准,并得到批准[审批文号:〔2019〕伦审第(05号)]。本研究与受试对象均签署知情同意书。结果①7144例孕妇中,NIPT提示胎儿SCA为27例(0.4%,27/7144)。胎儿SCA的27例胎儿中,13例(48.1%,13/27)胎儿染色体核型为45,X;6例(22.2%,6/27)为47,XXX;5例(18.5%,5/27)为47,XYY;3例(11.1%,3/27)为47,XXY。②对NIPT提示胎儿SCA的27例孕妇中,21例进一步进行羊水穿刺术胎儿染色体核型分析发现,12例无异常,其余9例的结果与NIPT结果相符,SCA阳性预测值为42.8%(9/21)。胎儿染色体核型异常的9例胎儿中,3例胎儿染色体核型为47,XXX;3例为47,XYY;2例为47,XXY;1例为45,X。③由于NIPT结果异常进一步进行羊水穿刺术结果亦异常的9例胎儿45,X,47,XXX,47,XXY和47,XYY阳性预测值分别为10.0%(1/10),75.0%(3/4),67.0%(2/3)和75.0%(3/4),假阳性率分别为90.0%(9/10),25.0%(1/4),33.0%(1/3)和25.0%(1/4)。④NIPT结果显示胎儿染色体核型为47,XNN者进一步行羊水穿刺术后提示真阳性者父母中位年龄均为37岁,高于假阳性者父母(30岁)。结论NIPT在筛查胎儿SCA方面具有较好的应用价值,但是假阳性率较高,仍需进一步进行产前诊断以确诊。     

Fetal loss following second trimester amniocentesis. Who is at greater risk? How to counsel pregnant women?

Objective: The purpose of this retrospective observational cohort study was to determine the impact of certain risk factors on fetal loss, after mid-trimester amniocentesis.

Material and methods: Six thousand seven-hundred and fifty-two (6752) consecutive amniocenteses with known pregnancy outcome performed during a 7-year period (2004–2010) were included in this study. Different maternal-, fetal- and procedure-related factors were evaluated in this study.

Results: During this 7-year period, 6752 cases who underwent amniocentesis, with complete data available were evaluated for the outcome and risk factors mentioned. Total fetal loss rate (FLR) up to the 24th week was 1.19%. Risk factors associated with increased risk of fetal loss after amniocentesis were maternal age (OR:2.0), vaginal spotting (OR:2.2) and serious bleeding (OR:3.5) during pregnancy, history of 2nd trimester termination of pregnancy (OR:4.0), history of more than three spontaneous (OR:3.0) or surgical first trimester abortions (OR:2.1), fibromas (OR:3.0) and stained amniotic fluid (OR:6.1).

Conclusions: Amniocentesis is a safe-invasive procedure for prenatal diagnosis with total FLR of 1.19% in our institution during the study period. The present study has emphasized the significance of certain risk factors for adverse outcome and therefore the need to individualize the risk.     

孕妇产前诊断指征与胎儿染色体异常的关系

目的探讨产前诊断指征和产前诊断胎儿染色体异常间的关系。方法选择2018年6月至2018年12月于贵港市人民医院就诊的孕妇100例,收集所有孕妇产前诊断指征的资料,同时收集羊膜腔穿刺术检测胎儿染色体核型分析的结果。结果胎儿染色体异常共9例,总异常率占9.00%,其中无创基因检测异常组的胎儿染色体异常检出率为60.00%,明显高于高龄组的3.03%、唐氏筛查高危组的5.26%及胎儿超声异常组的7.69%,差异均有统计学意义(P<0.05);夫妇染色体异常组的胎儿染色体异常检出率为50.00%,明显高于高龄组,差异均有统计学意义(P<0.05);高龄组、唐氏筛查高危组、胎儿超声异常组间异常检出率无明显差异(P>0.05)。结论产前诊断指征与胎儿染色体异常密切相关,羊膜腔穿刺行染色体核型分析,能够有效检出胎儿染色体异常,对于有产前诊断指征的孕妇应尽早接受产前诊断,以降低新生儿出生缺陷的发生率。     

Prenatal diagnosis of mosaicism for a distal 5p deletion in a single colony at amniocentesis in a pregnancy with a favorable outcome and a review of mosaic distal 5p deletion

ObjectiveWe present prenatal diagnosis of mosaicism for a distal 5p deletion in a single colony at amniocentesis with a favorable outcome, and we review the literature of mosaic distal 5p deletion.Case ReportA 35-year-old primigravid woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age. Amniocentesis revealed the result of 46,XY,del(5)(p13)[1]/46,XY[19]. Among 20 colonies of cultured amniocytes, all four cells in one colony had a karyotype of 46,XY,del(5)(p13) with a distal deletion of 5p13→pter, while the rest 19 colonies had a karyotype of 46,XY. Repeat amniocentesis was performed at 21 weeks of gestation. Conventional cytogenetic analysis revealed a karyotype of 46,XY in all 20 colonies. Simultaneous array comparative genomic hybridization (aCGH) using the DNA extracted from the uncultured amniocytes revealed no genomic imbalance. Prenatal ultrasound findings were unremarkable. At 38 weeks of gestation, a 3621-g male baby was delivered with no phenotypic abnormality. The cord blood had a karyotype of 46,XY. Postnatal urinary cells analysis by interphase fluorescence in situ hybridization (FISH) using a 5p terminal FISH probe detected no abnormal cell in the urine.ConclusionMosaicism for a distal 5p deletion in a single colony at amniocentesis can be associated with a favorable outcome.     

Prenatal diagnosis and molecular cytogenetic characterization of mosaicism for r(13), monosomy 13 and idic r(13) by amniocentesis

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of mosaicism for ring chromosome 13 [r(13)], monosomy 13 and isodicentric ring chromosome 13 [idic r(13)] by amniocentesis.Case reportA 24-year-old woman underwent amniocentesis at 23 weeks of gestation because of intrauterine growth restriction (IUGR) in the fetus. Amniocentesis revealed a karyotype of 46,XY,r(13)[23]/45,XY,-13[10]/46,XY,idic r(13)[2]. The parental karyotypes were normal. Array comparative genomic hybridization (aCGH) on cultured amniocytes revealed the result of arr 13q11q31.3 (19,436,286–92,284,309) × 1.85, arr 13q31.3q34 (92,288,514–115,107,733) × 1 [GRCh37 (hg19)], indicating a 22.82-Mb 13q31.3-q34 deletion and a 15–20% mosaicism for 13q11-q31.3 deletion. The pregnancy was subsequently terminated, and a malformed fetus was delivered with facial dysmorphism. The placental tissues had a karyotype of 46,XY,r(13)[18]/46,XY,-13,+mar[14]/45,XY,-13[8]. Polymorphic DNA marker analysis confirmed a maternal origin of the 13q deletion.ConclusionFetus with mosaic r(13), monosomy 13 and idic r(13) may present IUGR on prenatal ultrasound, and fetoplacental cytogenetic discrepancy may exist under such a circumstance.     

The role of genetic counseling on decisions of pregnant women aged 35 years or over regarding amniocentesis in Turkey

We investigated the effects of genetic counseling given before amniocentesis that is given based on maternal serum screening (using the cut-off value of 1/250) and genetic sonogram results (+/- abnormal ultrasound marker) on pregnant women who are 35 years and older age. Their attitudes towards amniocentesis after genetic counseling were evaluated. Among 340 women, 223 (65.6%) were in the high-risk group and 117 (34.4%) were in the low-risk group according to non-invasive test results. After counseling, 216 pregnant women (167 cases have high-risk, 49 cases who had low-risk) decided to have amniocentesis while 124 women (56 with high-risk and 68 with low-risk) declined it. Fourteen abnormal karyotypes were detected. All pregnant women who had fetuses with chromosomal aberrations were in high-risk group. Our study shows that screening by non-invasive prenatal diagnostic tool has an effect on families' choice of amniocentesis. The use of these test results during counseling decreased the number of amniocentesis in a ratio of 36.5%.