Intervenciones diagnósticas prenatales en un hospital público / Prenatal diagnostic interventions in a public hospital

The authors present a study of prenatal diagnostic interventions in a public hospital. The invasive prenatal diagnosis can be achieved by means of threee methods, aspirative punction of chorionic villous, extraction of amniotic fluid and fetal blood sample. Samples of chorionic villus are empoyed for citogenetic study, determination of the fetal cariotype or realization of a specific determination through technic FISH (Fluorescence in situ hybridization) or molecular genetics. Sample of amniotic fluid consists in the aspirative puncture under direct sonographic control of the amniotic cavity. During the period of the study, 9457 obstetric sonographies were performed with 121 genetic consultations of whom 46 resulted in invasive prenatal diagnostics. The results obtained are discussed (AU)

Obstetrical Outcomes of Amniocentesis or Chorionic Villus Sampling in Dichorionic Twin Pregnancies

BACKGROUND: Under certain situations, women with twin pregnancies may be counseled to undergo invasive prenatal diagnostic testing. Chorionic villus sampling and amniocentesis are the two generally performed invasive prenatal diagnostic tests. Studies comparing procedure-related fetal loss between first-trimester chorionic villus sampling and second-trimester amniocentesis in twin pregnancies are limited. This study aimed to evaluate the procedure-related fetal loss and the obstetrical outcomes of these two procedures, chorionic villus sampling and amniocentesis in twin pregnancies. METHODS: The data from dichorionic-diamniotic twin pregnancies on which first-trimester chorionic villus sampling (n = 54) or second-trimester amniocentesis (n = 170) was performed between December 2006 and January 2017 in a single center were retrospectively analyzed. The procedure-related fetal loss was classified as loss of one or all fetuses within 4 weeks of procedure, and overall fetal loss was classified as loss of one or all fetuses during the gestation. The groups were compared with respect to the procedure-related and obstetrical outcomes. RESULTS: The difference in proportion of procedure-related fetal loss rate (1.9% for chorionic villus sampling vs. 1.8% for amniocentesis; P = 1.000) and the overall fetal loss rate (7.4% for chorionic villus sampling vs. 4.7% for amniocentesis; P = 0.489) between the two groups was not significant. The mean gestational ages at delivery were not statistically significant. CONCLUSION: Both the overall fetal loss rate and the procedure-related fetal loss rate of chorionic villus sampling and amniocentesis in dichorionic twin pregnancies had no statistical significance. Both procedures can be safely used individually.

Morphometry of pectoral muscle fiber and intestinal villi of Calidris pusilla during the wintering period in Brazil / Morfometria da fibra muscular peitoral e das vilosidades intestinais de Calidris pusilla durante o período de invernada no Brasil

Migration is an event observed in several animals, such as shorebirds moving between the northern and southern hemispheres, during breeding and wintering intervals. Morphophysiological adaptations are necessary to allow the maintenance of migratory cycles and, therefore, studies with this focus can help clarify biological aspects related to migration. We analyzed the morphology variation in pectoral muscles and intestinal mucosa of Calidris pusilla, during different phases of the wintering period on the coast of Brazil. Fragments of pectoral muscles and duodenal were collected, fixed and processed for histology according to standard procedure, from specimens captured in a locality on the Brazilian coast. Modifications were found in the measured parameters among the three phases of wintering, arrival in Brazil (October, mid-period), January and departure to the Northern Hemisphere - May. The registered structural dynamism characterizes the growth of flight musculature and intestinal changes related to nutrition. Such changes occur temporarily due to the activities of preparation and migration between the northern and southern hemispheres.(AU)

A migração é um evento observado em vários animais, como as aves limícolas que se deslocam entre os hemisférios norte e sul, durante os intervalos de reprodução e invernada. Adaptações morfofisiológicas são necessárias para permitir a manutenção dos ciclos migratórios e, portanto, estudos com esse enfoque podem ajudar a esclarecer aspectos biológicos relacionados à migração. Analisamos a variação morfológica nos músculos peitorais e mucosa intestinal de Calidris pusilla, durante diferentes fases do período de invernada no litoral brasileiro. Fragmentos de músculos peitorais e duodenais foram coletados, fixados e processados ​​para histologia de acordo com o procedimento padrão, a partir de espécimes capturados na localidade da costa brasileira. O dinamismo estrutural registrado caracteriza o crescimento da musculatura de vôo e as alterações intestinais relacionadas à nutrição. As mudanças nos parâmetros medidos entre as três fases do inverno, chegada ao Brasil (outubro, meio período), janeiro e saída para o Hemisfério Norte. Tais mudanças ocorrem temporariamente devido às atividades de preparação e migração entre os hemisférios norte e sul.(AU)

Enfermedad trofoblástica gestacional / Gestational trophoblastic disease

El término enfermedad trofoblástica gestacional agrupa a un conjunto de trastornos caracterizados por una proliferación anormal de las vellosidades coriales placentarias. Las variedades más conocidas son la mola hidatiforme (completa y parcial), la mola invasora y el coriocarcinoma. Se presentan datos epidemiológicos, incluidos los factores de riesgo, una revisión sumaria de los rasgos clínicos y se enfatizan los cambios anatomopatológicos. A continuación se tratan aspectos diversos de entidades más raras como el tumor trofoblástico del sitio de implantación placentaria, y el tumor trofoblástico epiteliode. Para la estadificación se recurre a los estadios propuestos por la FIGO, aunque el uso de la tomografía con emisión de positrones, la biopsia de ganglio centinela y la quimioterapia neoadyuvante no están previstas en el esquema de la FIGO. El artículo está ilustrado con figuras a color y la bibliografía ha sido seleccionada y actualizada AU)

Change in rates of prenatal tests for chromosomal abnormality over a 12-year period in women of advanced maternal age

OBJECTIVE: In 2007, the American College of Obstetricians and Gynecologists (ACOG) recommended that all pregnant women be offered screening or diagnostic tests for chromosomal abnormalities regardless of their age. Noninvasive prenatal testing (NIPT) for common chromosomal aneuploidies was introduced as a screening test in case of high-risk pregnancies. We assessed the rates of prenatal tests in women aged 35 years and older. METHODS: A retrospective study was conducted to compare the rates of amniocentesis, chorionic villus sampling (CVS), serum screening, and NIPT from January 2005 through March 2017 in women aged 35 years and older. We divided the initial 12 months after NIPT introduction into 4-month intervals, beginning in April 2016 through March 2017. RESULTS: The rates of amniocentesis were 56% before the ACOG statement, 38% between the ACOG statement and NIPT introduction, and 10% after NIPT introduction (P=0.001). The rates of CVS during the same periods were 0.5%, 2.1%, and 4.3% (P=0.016), respectively. The rates of serum screening were 44.2%, 61.3%, and 55.1% (P=0.049), respectively. During the 3 quarters after NIPT introduction, the rates of amniocentesis were 16.2%, 12.3%, and 7.3% (P=0.002), respectively; the rates of serum screening were 62%, 54%, and 46% (P=0.03), respectively; and the rates of NIPT were 19.9%, 30.3%, and 39.5% (P=0.007), respectively. The rates of CVS over the same periods were not significantly different. CONCLUSION: The ACOG statement and NIPT introduction significantly decreased the rate of amniocentesis in women of advanced maternal age. NIPT also reduced the rate of serum screening.

Role of fetal ultrasound in prenatally diagnosed de novo balanced translocations

PURPOSE: This study aimed to investigate fetal ultrasonographic findings in cases of prenatally diagnosed de novo balanced translocations and the role of fetal ultrasound in prenatal genetic counseling. MATERIALS AND METHODS: We collected cases with de novo balanced translocations that were confirmed in chorionic villus sampling, amniocentesis, and cordocentesis between 1995 and 2016. A detailed, high-resolution ultrasonography was performed for prediction of prognosis. Chromosomes from the parents of affected fetuses were also analyzed to determine whether the balanced translocations were de novo or inherited. RESULTS: Among 32,070 cases with prenatal cytogenetic analysis, 27 cases (1/1,188 incidence) with de novo balanced translocations were identified. Fourteen cases (51.9%) showed abnormal findings, and the frequency of major structural anomalies was 11.1%. Excluding the major structural anomalies, all mothers who continued pregnancies delivered healthy babies. CONCLUSION: Results of a detailed, high-resolution ultrasound examination are very important in genetic counseling for prenatally diagnosed de novo balanced translocations.

Partial molar pregnancy and coexisting fetus with Turner syndrome: Case report and literature review

Partial hydatidiform mole and coexisting fetus is a rare entity with antecedent high risk of maternal and fetal complications, and risk of persistent trophoblastic disease in later life. Here, we report a case of twin pregnancy with live fetus identified as 45,X and normal placenta and another partial mole. Ultrasound scan at 10 weeks showed a hydrops fetus with a focal area of multicystic placenta. The patient underwent chorionic villus sampling and amniocentesis for chromosomal analysis, and the result was 45,X. Based on these finding, the patient then underwent induced abortion. Pathological examination (immunohistochemical staining) of the placenta confirmed the partial mole. This report suggests that careful prenatal ultrasonography and appropriate karyotyping in a molar pregnancy and coexisting fetus enable early diagnosis and may be beneficial for prognosis.

Quantitative fluorescent polymerase chain reaction for rapid prenatal diagnosis of fetal aneuploidies in chorionic villus sampling in a single institution

OBJECTIVE: To validate quantitative fluorescent polymerase chain reaction (QF-PCR) via chorionic villus sampling (CVS) for the diagnosis of fetal aneuploidies. METHODS: We retrospectively reviewed the medical records of consecutive pregnant women who had undergone CVS at Cheil General Hospital between December 2009 and June 2014. Only cases with reported QF-PCR before long-term culture (LTC) for conventional cytogenetic analysis were included, and the results of these two methods were compared. RESULTS: A total of 383 pregnant women underwent QF-PCR and LTC via CVS during the study period and 403 CVS specimens were collected. The indications of CVS were as follows: abnormal first-trimester ultrasonographic findings, including increased fetal nuchal translucency (85.1%), advanced maternal age (6.8%), previous history of fetal anomalies (4.2%), and positive dual test results for trisomy 21 (3.9%). The results of QF-PCR via CVS were as follows: 76 (18.9%) cases were identified as trisomy 21 (36 cases), 18 (33 cases), or 13 (seven cases), and 4 (1.0%) cases were suspected to be mosaicism. All results of common autosomal trisomies by QF-PCR were consistent with those of LTC and there were no false-positive findings. Four cases suspected as mosaicism in QF-PCR were confirmed as non-mosaic trisomies of trisomy 21 (one case) or trisomy 18 (three cases) in LTC. CONCLUSION: QF-PCR via CVS has the advantage of rapid prenatal screening at an earlier stage of pregnancy for common chromosomal trisomies and thus can reduce the anxiety of parents. In particular, it can be helpful for pregnant women with increased fetal nuchal translucency or abnormal first-trimester ultrasonographic findings.

Non-invasive prenatal test using cell free DNA

Although conventional prenatal screening tests for Down syndrome have been developed over the past 20 years, the positive predictive value of these tests is around 5%. Through these tests, many pregnant women have taken invasive tests including chorionic villi sampling and amniocentesis for confirming Down syndrome. Invasive test carries the risk of fetal loss at a low but significant rate. There is a large amount of evidence that non-invasive prenatal test (NIPT) using cell free DNA in maternal serum is more sensitive and specific than conventional maternal serum and/or ultrasound screening. Therefore implementing NIPT will increase aneuploidy detection rate and concurrently decrease fetal loss rate accompanying invasive test. More than 1,000,000 NIPT were performed globally since 2011. The uptake rate of NIPT is expected to increase more rapidly in the future. Moreover, as a molecular genetic technique advances, NIPT can be used for not only common aneuploidy screening but single gene disorder, microdeletion, and whole fetal genome sequencing. In this review, I will focus on the NIPT for common aneuploidies such as trisomy 13, 18, and 21.

Application of digital polymerase chain reaction technology for noninvasive prenatal test

Recently, noninvasive prenatal test (NIPT) has been adopted as a primary screening tool for fetal chromosomal aneuploidy. The principle of NIPT lies in isolating the fetal fraction of cell-free DNA in maternal plasma and analyzing it with bioinformatic tools to measure the amount of gene from the target chromosome, such as chromosomes 21, 18, and 13. NIPT will contribute to decreasing the need for unnecessary invasive procedures, including amniocentesis and chorionic villi sampling, for confirming fetal aneuploidy because of its higher positive predictive value than that of the conventional prenatal screening method. However, its greater cost than that of the current antenatal screening protocol may be an obstacle to the adoption of this innovative technique in clinical practice. Digital polymerase chain reaction (dPCR) is a novel approach for detecting and quantifying nucleic acid. dPCR provides real-time diagnostic advantages with higher sensitivity, accuracy, and absolute quantification than conventional quantitative PCR. Since the groundbreaking discovery that fetal cell-free nucleic acid exists in maternal plasma was reported, dPCR has been used for the quantification of fetal DNA and for screening for fetal aneuploidy. It has been suggested that dPCR will decrease the cost by targeting specific sequences in the target chromosome, and dPCR-based noninvasive testing will facilitate progress toward the implementation of a noninvasive approach for screening for trisomy 21, 18, and 13. In this review, we highlight the principle of dPCR and discuss its future implications in clinical practice.

Chorionic villus sampling

Chorionic villus sampling has gained importance as a tool for early cytogenetic diagnosis with a shift toward first trimester screening. First trimester screening using nuchal translucency and biomarkers is effective for screening. Chorionic villus sampling generally is performed at 10-12 weeks by either the transcervical or transabdominal approach. There are two methods of analysis; the direct method and the culture method. While the direct method may prevent maternal cell contamination, the culture method may be more representative of the true fetal karyotype. There is a concern for mosaicism which occurs in approximately 1% of cases, and mosaic results require genetic counseling and follow-up amniocentesis or fetal blood sampling. In terms of complications, procedure-related pregnancy loss rates may be the same as those for amniocentesis when undertaken in experienced centers. When the procedure is performed after 9 weeks gestation, the risk of limb reduction is not greater than the risk in the general population. At present, chorionic villus sampling is the gold standard method for early fetal karyotyping; however, we anticipate that improvements in noninvasive prenatal testing methods, such as cell free fetal DNA testing, will reduce the need for invasive procedures in the near future.

Analysis of increased nuchal translucency: Chorionic villi sampling and second-trimester level II sonography

PURPOSE: To assess the outcomes of increased fetal nuchal translucency (NT), to aid in prenatal counseling and management in our practice. MATERIALS AND METHODS: We retrospectively reviewed the medical records of patients who underwent first trimester fetal karyotyping using chorionic villi sampling (CVS) and second trimester level II sonography for a fetal NT thickness > or =3.0 mm between 11 weeks and 13 weeks 6 days' gestation, at Gyeongsang National University Hospital. Pediatric medical records and a telephone interview were used to follow-up live-born children. Exclusion criteria included incomplete data and CVS for other indications. RESULTS: Seventy cases met the inclusion criteria (median NT thickness, 4.7 mm; range, 3.0-16.1 mm). Twenty-nine cases (41.4%) were aneuploid. The prevalence of chromosomal defects increased with NT thickness: NT 3.0-3.4 mm, 16.7%; NT 3.5-4.4 mm, 27.3%; NT 4.5-5.4 mm, 66.7%; NT 5.5-6.4 mm, 37.5%; NT > or =6.5 mm, 62.5%. The most common karyotype abnormality was trisomy 18 (n=12), followed by trisomy 21 (n=9). In chromosomally normal fetuses (n=41), fetal death occurred in 2 cases (4.9%), and structural malformations were found in 11 cases (26.8%). In chromosomally and anatomically normal fetuses (n=28), one child had neurodevelopmental delay (3.6%). Twenty-eight infants who had a prenatal increased NT were alive and well at follow-up (40%). CONCLUSION: Outcomes of increased fetal NT might help inform prenatal counseling and management. The high prevalence of chromosomal defects associated with increased fetal NT implies that CVS should be performed in the first trimester, particularly considering the stress associated with an uncertain diagnosis.

Characterization of a prenatally diagnosed de novo der(X)t(X;Y)(q27;q11.23) of fetus

A 31-year-old woman, who was pregnant with twins, underwent chorionic villus sampling because of increased nuchal translucency in one of the fetuses. Cytogenetic analysis showed a normal karyotype in the fetus with increased nuchal translucency. However, the other fetus, with normal nuchal translucency, had a derivative X chromosome (der(X)). For further analysis, fluorescence in situ hybridization (FISH) and additional molecular studies including fragile X analysis were performed. FISH analysis confirmed that the Y chromosome was the origin of extra segment of the der(X). The X-chromosome breakpoint was determined to be at Xq27 by FMR1 CGG repeat analysis, and the Y-chromosome breakpoint was determined to be at Yq11.23 by the Y chromosome microdeletion study. To predict the fetal outcome, the X-inactivation pattern was examined, and it revealed non-random X inactivation of the der(X). To the best of our knowledge, the identification of an unbalanced Xq;Yq translocation at prenatal diagnosis has never been reported. This study was performed to identify precise breakpoints and the X-inactivation pattern as well as to provide the parents with appropriate genetic counseling.

Paracentric Inversions Found in Prenatal Diagnosis

PURPOSE: This study was designed to confirm whether the paracentric inversions of fetuses and parents may be harmless. MATERIALS AND METHODS: We report 10 cases (0.14%) with paracentric inversions among 7,181 prenatal cases observed during prenatal diagnosis performed at Cheil General Hospital between January 2009 and June 2013. We used cytogenetic GTL- and RBG-banding techniques. RESULTS: Of the 10 cases, nine cases were transmitted from each of the parents, and one case was de novo. Nine cases were phenotypically normal up to one month of age after birth. One case was lost to follow-up. We present prenatal diagnosis and follow-up examination of the fetuses with paracentric inversion. CONCLUSION: Based on our cases, most paracentric inversions are considered to be harmless. The precise identification of paracentric inversions might be clinically important and helpful for genetic counseling.

Non-invasive prenatal diagnosis of fetal trisomy 21 using cell-free fetal DNA in maternal blood

Since the existence of cell-free fetal DNA (cff-DNA) in maternal circulation was discovered, it has been identified as a promising source of fetal genetic material in the development of reliable methods for non-invasive prenatal diagnosis (NIPD) of fetal trisomy 21 (T21). Currently, a prenatal diagnosis of fetal T21 is achieved through invasive techniques, such as chorionic villus sampling or amniocentesis. However, such invasive diagnostic tests are expensive, require expert technicians, and have a miscarriage risk approximately 1%. Therefore, NIPD using cff-DNA in the detection of fetal T21 is significant in prenatal care. Recently, the application of new techniques using single-molecular counting methods and the development of fetal-specific epigenetic markers has opened up new possibilities in the NIPD of fetal T21 using cff-DNA. These new technologies will facilitate safer, more sensitive and accurate prenatal tests in the near future. In this review, we investigate the recent methods for the NIPD of fetal T21 and discuss their implications in future clinical practice.

Análise dos resultados maternos e fetais dos procedimentos invasivos genéticos fetais: um estudo exploratório em Hospital Universitário / Analysis of fetal and maternal results from fetal genetic invasive procedures: an exploratory study at a University Hospital

OBJETIVO: Caracterizar as indicações das gestantes que procuraram o serviço de Medicina Fetal do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo para realização de procedimentos invasivos diagnósticos e avaliar os resultados dos cariótipos fetais e de suas gestações. MÉTODOS: Estudo observacional retrospectivo das gestantes que realizaram biópsia de vilo corial (BVC), amniocentese e cordocentese no período de fevereiro de 2005 a dezembro de 2009. Não foram incluídos outros procedimentos diagnósticos ou procedimentos terapêuticos. O resultado da gestação foi obtido através de consulta de prontuário eletrônico e/ou físico e/ou contato telefônico. RESULTADOS: Foram realizados 713 procedimentos (113 BVC, 340 amniocenteses e 260 cordocenteses). A principal indicação para a realização dos procedimentos invasivos foi a presença de alterações estruturais nos fetos, seguido por valores aumentados da translucência nucal e pela idade materna avançada. O cariótipo fetal esteve alterado em 186 casos (26,1%). A trissomia do cromossomo 18 foi a aneuploidia mais comum, seguida pela trissomia do 21, a monossomia do X e a trissomia do cromossomo 13. Ocorreram 4,9% de abortamento, 25,7% de natimortos e 13% de neomortos. Oito gestantes optaram pela interrupção judicial, e 99% das gestantes cujos fetos não apresentavam malformação e que apresentavam cariótipo fetal normal tiveram nativivos.

OBJECTIVE: To characterize the indications of pregnant women who sought the Fetal Medicine Services of the Hospital das Clínicas, at the Medical School of the Universidade de São Paulo for performing invasive diagnostic procedures, and to evaluate the results of fetal karyotypes and their pregnancies. METHODS: A retrospective and observational study on pregnant women who underwent chorionic villus sampling (CVS), amniocentesis, and cordocentesis in the period from February, 2005 to December, 2009. Other diagnostic or therapeutic procedures were not included. The result of pregnancy was obtained by consulting patient electronic records, medical records, and/or telephone call. RESULTS: 713 procedures were performed (113 CVS, 340 amniocenteses, and 260 cordocenteses). The main indication for performing invasive procedures was the presence of structural changes in fetuses, followed by increased values of nuchal translucency, and advanced maternal age. Fetal karyotype was altered in 186 cases (26.1%). The 18 trisomy was the commonest aneuploidy followed by the 21 trisomy, X monosomy, and 13 trisomy. There were 4.9% cases of miscarriage, 25.7% cases of stillborn infants, and 13% cases of neonatal deaths. Eight pregnant women opted for legally induced abortion. 99% of pregnant women whose fetuses did not present abnormalities and presented normal fetal karyotype had infants who were born alive.

Epidemiological study of the patients referred for thalassemia diagnosis using chorionic villous sampling [CVS] in genetic laboratory of Dastgheib hospital, Shiraz, 2011

Pre-natal diagnosis is the most effected way to prevent genetic diseases in a society. The aim of this research was to show the prevention level of the birth of the children with major thalassemia disorder and the demographic condition of the people referring to the Shahid Dastgheib Genetic Center in Shiraz for the pre natal diagnosis. The present research was a cross- sectional [descriptive, analytical] one. In this study, the amount of sampling was done by census in a way that all the case [372 cases] related to the year 2010. The questionnaire was prepared based on the information present in the files. In order to compare the quantitative and qualitative variables, two sample t - test and K sample t- test were used. Out of 372 fetuses tested, 25.5% had major thalassemia, 48.7% minor thalassemia, 0.8% intermediate, 1.3% sickle cell, and 23.7% were healthy. All the cases diagnosed with thalassemia were introduced for abortion, and abortion was carried out. Major thalassemia was more prevalent in Lore tribes [32.9%], which was more in comparison to the members of others tribes. In order to prevent major thalassemia, it is important to identify the gene carriers and prevent their marriage. Nevertheless, in many places in the country, especially in the villages and rural areas, the couples do the experiment after they have already gotten emotionally involved and made the arrangements to get married; therefore they're unwilling to stop the marriage. As a result, post-nuptial CVS during pregnancy is crucial

Invasive & non-invasive approaches for prenatal diagnosis of haemoglobinopathies: Experiences from India.

The thalassaemias and sickle cell disease are the commonest monogenic disorders in India. There are an estimated 7500 - 12,000 babies with β-thalassaemia major born every year in the country. While the overall prevalence of carriers in different States varies from 1.5 to 4 per cent, recent work has shown considerable variations in frequencies even within States. Thus, micromapping would help to determine the true burden of the disease. Although screening in antenatal clinics is being done at many centres, only 15-20 per cent of pregnant women register in antenatal clinics in public hospitals in the first trimester of pregnancy. There are only a handful of centres in major cities in this vast country where prenatal diagnosis is done. There is considerable molecular heterogeneity with 64 mutations identified, of which 6 to 7 common mutations account for 80-90 per cent of mutant alleles. First trimester foetal diagnosis is done by chorionic villus sampling (CVS) and DNA analysis using reverse dot blot hybridization, amplification refractory mutation system (ARMS) and DNA sequencing. Second trimester diagnosis is done by cordocentesis and foetal blood analysis on HPLC at a few centres. Our experience on prenatal diagnosis of haemoglobinopathies in 2221 pregnancies has shown that >90 per cent of couples were referred for prenatal diagnosis of β-thalassaemia after having one or more affected children while about 35 per cent of couples were referred for prenatal diagnosis of sickle cell disorders prospectively. There is a clear need for more data from India on non-invasive approaches for prenatal diagnosis.

Ten-year Clinical Study of Chorionic Villus Sampling

PURPOSE: We evaluated indications for chorionic villus sampling (CVS), the positive predictive value of CVS for fetal chromosomal abnormalities, and the fetal loss rate after CVS at CHA Medical Center. MATERIALS AND METHODS: We reviewed the medical records of 511 cases of CVS performed between 67 and 120 days of gestation for prenatal cytogenetic diagnosis from April 2000 to April 2010. Fetal karyotypes were obtained by direct and indirect culture methods. RESULTS: The most common indications for CVS were abnormal ultrasonic findings including increased nuchal translucency (294/635, 46.3%). The positive predictive value of abnormal karyotyping according to indication for CVS was highest in cases with abnormal parental karyotypes (14/21, 66.7%). Mosaicism revealed by CVS comprised 3.1% of the sample (16/509). Amniocentesis revealed two cases of true mosaicism and 11 cases of confined placental mosaicism. The fetal loss rate within 4 weeks of the procedure was 1.2% (6/511). CONCLUSION: If CVS is performed by an expert clinician, it is a feasible and reliable procedure for prenatal genetic diagnosis. When CVS indicates mosaicism, the finding should be confirmed by amniocentesis to distinguish true mosaicism from confined placental mosaicism.