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Prenatal testing for limb reduction defects. How patients' views affect their choice of CVS.

OBJECTIVE: To determine the effect of reports and media coverage on chorionic villus sampling (CVS) and limb reduction defects (LRD) on patients' utilization of CVS for prenatal testing for advanced maternal age and to quantitate the relation of preferences for CVS and amniocentesis (AMN) outcomes to test utilization. STUDY DESIGN: We compared CVS and AMN utilization rates in two groups of women seen at one academic medical center before and after publicity concerning CVS and LRD. We measured preferences, in rating-scale units, for potential outcomes of prenatal testing in the after-publicity group. Relationships between preferences and CVS utilization were examined using multivariate methods. RESULTS: The proportion of women utilizing CVS for prenatal testing declined significantly for the after-publicity group (23%) as compared with the prepublicity group (47.4%, P = .0001). Belief that the birth of a child with LRD after CVS was worse than a similar birth after AMN significantly reduced the odds of choosing CVS. A decrement in preference for a child with LRD after CVS of 5 rating-scale units reduced the likelihood of CVS by 15% (confidence interval [CI], 1-28%); a decrement of 10 units reduced the likelihood of CVS by 28% (CI, 1-48%). This effect persisted after adjustment for demographic and obstetric covariates, prior prenatal testing, locus of decision making (patient versus physician or shared) and other maternal preferences for outcomes of prenatal testing. CONCLUSION: Lower patient preference for a child with LRD after CVS was an independent predictor of choosing AMN over CVS and was probably responsible for the significant decrease in CVS utilization at our hospital.

Amniocentesis↗

Improved prenatal detection of fra(X)(q27.3): methods for prevention of false negatives in chorionic villus and amniotic fluid cell cultures.

The reliable detection of fra(X)(q27.3) in prenatal samples is important for providing genetic counseling. We have identified 5 new cases of prenatal fragile X [fra(X)] detection in 3 chorionic villus sample (CVS) and 2 amniotic fluid (AF) cell cultures. In 4 of the 5 cases, either excess thymidine (THY) or a combination of THY and 5-fluorodeoxyuridine (FUdR) was clearly superior to FUdR alone as fra(X) inducers. Amniocytes from one case were cultured only in RPMI-1640 and later exposed to FUdR or THY separately. They showed only 2% fra(X) while parallel cultures initiated in Chang medium and incubated in RPMI for at least 7 days (recovery) before fra(X) induction exhibited strikingly increased fra(X) frequencies. Chang medium alone will not allow fra(X) induction in AF (Jenkins EC, Brown WT [1986]: "Genetic Disorders and the Fetus: Diagnosis, Prevention and Treatment." New York: Plenum Press, pp 185-204). Now, using CVS cells, we report that only 1% and 0% fra(X) were detected using FUdR or THY in cells cultured in RPMI for 4 days after removal from Chang medium. Cells with 7 days "recovery" in RPMI exhibited increases from 2 to 6%. Therefore, we have found that Chang medium is very helpful when the appropriate recovery time in another medium is allowed before fra(X) induction. Some false negative reports can be attributed to: induction in Chang medium alone; lack of sufficient recovery time after initiating cells in Chang before induction; and unavailability of the excess THY fra(X) induction system.(ABSTRACT TRUNCATED AT 250 WORDS)

Amniocentesis↗

Racial-ethnic differences in prenatal diagnostic test use and outcomes: preferences, socioeconomics, or patient knowledge?

OBJECTIVE: To determine whether use of chorionic villus sampling and amniocentesis varies by racial-ethnic group and, if so, whether this variation is reflected in the prevalence of Down syndrome-affected births to women age 35 and older, the ages at which prenatal diagnosis is offered currently. METHODS: Medical charts of 238 women 35 years of age and older presenting for care at the University of California at San Francisco by 20 gestational weeks in 1993 and 1994 were reviewed to assess prenatal diagnostic test use. The prevalence of Down syndrome-affected births in California during 1983-1991 was obtained from the Birth Defects Monitoring Program. RESULTS: Latinas and African-American women were much less likely to undergo prenatal diagnosis than were whites and Asians. Odds ratio (OR) and 95% confidence intervals (CI), with white women serving as the reference group, were as follows: Asians 1.16 (0.57-2.36), Latinas 0.19 (0.08-0.43), and African-Americans 0.19 (0.04-0.49). Trends persisted, at diminished magnitude, after adjustment for socioeconomic characteristics: OR for Asians 1.77 (0.78-3.98) Latinas 0.28 (0.09-0.83) , and African-Americans 0.33 (0.10-1.10). Non-white women age 35 and older were significantly more likely than white women to give birth to a Down syndrome-affected infant: risk ratios for Asians 1.81 (1.61-2.03), Latinas 3.00 (2.74-3.28), and African-Americans 1.86 (1.63-2.11). CONCLUSION: Racial-ethnic differences exist in prenatal diagnostic test use and associated outcomes in women aged 35 and older. Socioeconomic factors are partially responsible; patient education and preferences may play a role.

Adult↗

Prenatal testing for Down syndrome in the Jewish and non-Jewish populations in Israel.

The present work evaluated the efficacy of a prenatal diagnosis program in which amniocentesis and chorionic villus sampling were offered free of charge to all pregnant women in Israel aged > or = 37 years. The number of Down syndrome (DS) live births that occurred during the period of the program (1978-92) was correlated to the prevalence of old maternal age (> 35 years) and the utilization of prenatal test in the Jewish and non-Jewish populations in 1990 and 1992. It was noted that in the Jewish population, there was a slight increase in the DS live birth rate, from 1.05 in 1978, to 1.37 DS cases/1,000 live births in 1987, which corresponded to an increase in the prevalence of older pregnant women, from 8.0% in 1978 to 14.8% in 1987. Thereafter, however, there was a continuous decline, to 0.71 DS cases/1,000 live births in 1992, as a result of increased acceptance of prenatal testing by women > or = 37 years (67%) and, recently, also by younger women (from 5.6% in 1990 to 14% in 1992). In the non-Jewish population, there has been a very low acceptance rate of prenatal testing (23.3-16.1% in women > or = 37 years and 0.36-0.63% in women < 37 years). As a result, a very low prenatal detection rate (8-16% of all DS cases) and a high prevalence of DS live births (1.4 cases/1,000 live births) were observed. We suggest that a unique genetic counseling approach is required in the non-Jewish population to improve prenatal DS prevention in Israel.

Adult↗

[Fears of pregnant women if prenatal examination yields or does not yield any findings].

OBJECTIVE: Besides a medical point of view, prenatal diagnosis also has psychological effects on the pregnant woman. We studied the state of anxiety before and after prenatal examination with unsuspicious and suspicious prenatal findings. MATERIAL AND METHODS: In a consecutive sample of 332 pregnant women presenting between the 12th and 21st week of gestation for prenatal malformation scan (level three reference centre, Unit for Prenatal Medicine, Department of Obstetrics and Gynaecology, Medical University of Lübeck) we ascertained state and trait anxiety (Spielberger) before prenatal examination and state anxiety after prenatal examination with unsuspicious and suspicious findings. RESULTS: In the sample of N = 332 pregnant women prenatal examination showed a suspicious finding in 37 fetuses (11.1 %) and an unsuspicious finding in 295 fetuses (88.9 %). Before prenatal examination there is no difference (Mann-Whitney-Test, P = 0.286) between the group with negative results and the pregnant women with a positive result for the trait anxiety scale; however, there is a significant difference (Mann-Whitney-Test, P = 0.014*) for the scale of state anxiety. After prenatal examination the evaluation of the state anxiety questionnaire shows a significant (Mann-Whitney-Test, P = 0.000*) difference between pregnant women with an unsuspicious finding and pregnant women with a suspicious finding. State-anxiety is significantly reduced after examination if the prenatal scan is unsuspicious (Wilcoxon-Test, P = 0.000*), but there is no significant difference between pre-and post-examination anxiety if there is a positive finding (Wilcoxon-Test, P = 0.399). Evaluating aspects of anxiety as regards content, it can be demonstrated that before prenatal examination the pregnant women are just as much afraid of a malformation being detected as of it being missed. CONCLUSIONS: Suspecting or knowing about a malformation of the unborn means a complex process of coping and an intense psychosocial strain for a pregnant woman. Besides the fear of a detected malformation the pregnant women state equal fear of a malformation being missed. In contrast to this the immediate feedback of a negative finding during ultrasound examination leads to a significant reduction of anxiety and to an emotional relief for the pregnant woman.

Adult↗

Mosaicism for trisomy 12: four cases with varying outcomes.

Trisomy 12 observed in chorionic villus sampling (CVS) may reflect generalized mosaicism or indicate mosaicism confined to only the placenta. In this report, four cases of trisomy 12 observed in CVS or cultured placental biopsies with varying outcomes are presented. Seven dinucleotide repeat polymorphisms for chromosome 12 were used to determine the chromosome 12 origins in the fetus or child and to delineate the mechanism(s) that gave rise to the trisomy. In two cases (cases A and C), the mosaicism was confined to the placenta, resulting in normal liveborns. Although, in one case, the molecular results suggested an apparent duplication of one paternal chromosome 12 in the placenta, normal biparental inheritance was found in the diploid fetal cell line in both cases. In two other cases (cases B and D), trisomy 12 was observed in both extraembryonic and fetal tissues. In one of these pregnancies, a child was born by Caesarean section at 37 weeks because of intrauterine growth retardation and oligohydramnios, and resulted in neonatal death. Molecular markers and fluorescence in situ hybridization (FISH) revealed low-level trisomy 12 mosaicism in the spleen. In the fourth case, fetal abnormalities were detected on ultrasound and low-level trisomy 12 mosaicism was observed in amniotic fluid cells using conventional cytogenetics and FISH. Molecular markers revealed a maternal meiosis I non-disjunction of chromosome 12 in DNA from a cultured placental biopsy. Although predicting the outcomes of pregnancies involving confined placental mosaicism remains difficult, molecular techniques are valuable tools for distinguishing uniparental from biparental disomy and mechanisms of mosaicism.

Adult↗

Chorionic villus sampling compared with amniocentesis and the difference in the rate of pregnancy loss.

OBJECTIVE: To compare loss rates following amniocentesis and chorionic villus sampling (CVS) over time. METHODS: A retrospective cohort study of all amniocentesis and CVS procedures resulting in a normal karyotype from 1983-2003 at a single prenatal diagnostic referral center was conducted. Pregnancy loss rates for amniocentesis, CVS, and nonintervention groups (ie, those who had nuchal translucency screening or counseling, but no procedure) were compared using the chi 2 test. Year of procedure, maternal age, parity, race or ethnicity, and gestational age at procedure were controlled for in multivariable logistic regression models. RESULTS: There were 9,886 CVS and 30,893 amniocentesis procedures performed during the study period that resulted in a normal karyotype. The overall loss rates were 3.12% for CVS and 0.83% for amniocentesis (P < .001). When examined by 5-year intervals, there was a statistically significant decrease in the CVS loss rate (P < .001) and a nonsignificant lesser decrease in the loss rate for amniocentesis over time. Although the pregnancy loss rate from CVS over the entire study period was higher than from amniocentesis (adjusted odds ratio 4.23, 95% confidence interval 2.29-7.81), in the most recent time period, 1998 to 2003, there was no difference between the two procedures (adjusted odds ratio 1.03, 95% confidence interval 0.23-4.52). CONCLUSION: The loss rates for both amniocentesis and CVS at our institution have decreased over time. Because the decrease in loss rate for CVS has been greater, there is no longer a statistically significant difference between the two. These results are informative in both patient counseling and establishing widespread prenatal diagnostic and screening programs.

Abortion, Spontaneous↗

Placental mosaicism is associated with unexplained second-trimester elevation of MShCG levels, but not with elevation of MSAFP levels.

In this patient-control study, we examined the impact of placental mosaicism on the concentrations of maternal serum human chorionic gonadotropin (MShCG) and maternal serum alpha-fetoprotein (MSAFP) in the second trimester of pregnancy. Patient and control groups were selected from 2347 women with a singleton pregnancy, who underwent chorionic villous sampling in the first trimester and from whom second-trimester serum samples had been collected. The concentrations of both serum markers, expressed in multiples of the median (MOM), in 35 women with confined placental mosaicism (CPM) were compared with those in 70 controls with uncomplicated pregnancies. Elevated MSAFP or MShCG was defined as a concentration of > or = 2.0 MOM. Of the 35 pregnancies with CPM, none had an elevated MSAFP level, as opposed to two out of the 70 women (2.9 per cent) in the control group (P = NS). Nine women in the placental mosaicism group (26 per cent) had an MShCG level of > or = 2.0 MOM, compared with five in the control group (7.1 per cent; P = 0.0135). Nineteen women in the placental mosaicism group (54 per cent) were screen-positive for Down's syndrome (cut-off 1:250), compared with 17 women (24 per cent) in the control group (P = 0.0042; relative risk = 2.3). The three highest MShCG levels were found in pregnancies with CPM that involved trisomy 16; all these women delivered a small-for-gestational age (SGA) infant. CPM, especially with trisomy 16, is associated with elevated levels of MShCG, but not with elevated levels of MSAFP. It is an important cause of false-positive results in serum screening programmes for fetal Down's syndrome. It is possible that abnormal MShCG levels in pregnancies with CPM result from dysfunctional placenta, caused by chromosomally abnormal areas. We therefore recommend increased surveillance of pregnancies with unexplained elevated MShCG levels.

Adult↗

The clinical significance of ultransonographically detected subchorionic hemorrhages.

OBJECTIVES: The null hypothesis is that there is no difference in outcome when pregnancies with ultrasonographically documented subchorionic hemorrhages are compared with those without these hemorrhages. STUDY DESIGN: We performed a case-control study, utilizing our computerized ultrasonographic database. Cases were matched with two or three controls in two separate control groups. Matching criteria were maternal age, gestational age at scan, and invasive procedures (chorionic villus sampling or amniocentesis). General exclusion criteria were absence of fetal heart motion and fetal anomalies. Presence of subchorionic hemorrhage was an exclusion criterion for both control groups; however, in addition, presence of vaginal bleeding was a further criterion for one of the two. Statistical analysis was performed with chi2 analysis and Yates' correction. Odd ratios and 95% confidence intervals were calculated. RESULTS: There was no difference in maternal characteristics between the cases and controls. The incidence of subchorionic hemorrhage was 1.3%. There was an increased risk of miscarriage (odds ratio 2.8, 95% confidence interval 1.7 to 7.4), stillbirth (4.5, 1.5 to 13.2), abruptio placentae (11.2, 2.7 to 46.4), and preterm labor (2.6, 1.5 to 4.6) when cases were compared with controls without subchorionic hemorrhage or bleeding. These risks were also increased in comparison with the control group with bleeding, except with respect to miscarriage. In this case the risks were similar in both cases and controls but increased with respect to the controls without bleeding. The mean birth weight was lower in the cases than in both control groups. CONCLUSION: The presence of an ultransonographically detected subchorionic hemorrhage increases the risk of miscarriage, stillbirth, abruptio placentae, and preterm labor. The presence of bleeding alone appears to increase the risk of miscarriage. It is unclear whether the subchorionic hemorrhage is causative or whether it is simply a sign of an underlying process that produces these negative effects.

Abortion, Spontaneous↗

Long-term follow-up of infants after transcervical chorionic villus sampling and after amniocentesis to compare congenital abnormalities and health status.

OBJECTIVES: Next to procedure-related fetal loss, other adverse effects of invasive prenatal diagnosis have been reported: limb defects after chorionic villus sampling (CVS) or early amniocentesis and respiratory distress after amniocentesis (AC). Because minor abnormalities may be overlooked in routine follow-up, we obtained long-term follow-up data after CVS and AC. METHODS: 1509 women with a singleton pregnancy who had transcervical CVS were matched by age and season of conception with 1509 women with singleton pregnancies who had AC. All procedures were performed during 1985-1991 for advanced maternal age >35 years. Data regarding congenital malformations (classified according Eurocat), neonatal and paediatric morbidity and complications of motor development, speech, hearing and visual function were obtained by questionnaire in 1993-1995. RESULTS: Short-term outcome was known in all but ten infants. Questionnaires with a structured design were mailed to all women with a surviving infant (n=2810); 86.7% responded. No difference was detected between infants after CVS compared with infants after AC regarding congenital malformations (7.2% versus 6.3%), neonatal morbidity (15.1% versus 15.9%), paediatric morbidity with clinical treatment (7.7% versus 6.3%) or outpatient treatment only (43.9% versus 40.3%) and evident function disturbance (2.0% versus 2.0%) or doubtful function disturbance (6.3% versus 6.8%). The number of infants with physical growth <10th centile for Dutch infants was equal (10.1%). Sub-analysis for limb abnormalities or respiratory complications did not demonstrate differences between infants after CVS and AC. Only 10% of all congenital malformations were already known through routine post-partum follow-up. CONCLUSIONS: An extensive long-term survey could not demonstrate differences of health status between infants after prenatal diagnosis by transcervical CVS and AC.

Adult↗

Confined placental mosaicism for trisomies 2, 3, 7, 8, 9, 16, and 22: their incidence, likely origins, and mechanisms for cell lineage compartmentalization.

Analysis of confined placental mosaicism (CPM) for trisomies 2, 3, 7, 8, 9, 16, and 22, in diagnostic chorionic villus sampling procedures, demonstrates apparent incidences of CPM for individual trisomies of between 9 and 91 cases per 100,000 pregnancies, with trisomy 7 being the most common. More detailed analysis of the percentage of aneuploid cells present, and the distribution of abnormality between the cytotrophoblast and extra-embryonic mesoderm cell lineages, shows a highly specific pattern for each chromosome. Theoretical considerations, in conjunction with direct observations, indicate that the overriding influence on the patterns of cell distribution seen in CPM is the distribution of aneuploid cells laid down during blastogenesis. This in turn reflects closely the origin of mosaicism from either correction of a trisomic conception or post-fertilization somatic error. The pattern of aneuploid cells for each trisomy, as seen at the end of the first trimester and later in pregnancy, can therefore be used to predict the relative contribution of meiotic and mitotic errors to CPM, and hence the likely incidences of uniparental disomy from this source, upd(16)mat being the most common (1 in 10,000 continuing pregnancies). In addition, CPM for trisomies 2, 3, and 8 shows strong evidence of a non-random distribution of aneuploid cells between the different extra-embryonic cell lineages. Analysis of comparable data from spontaneous abortion material repeats this non-random pattern for trisomies 2 and 3, and suggests that a similar phenomenon may also be occurring for trisomy 22. A non-random distribution could be attributable to selection for or against, or intolerance of, particular trisomic cells in certain lineages, but is more probably a result of either cell lineage-specific non-disjunction or consistent uneven compartmentalization of aneuploid cells during blastocyst development.

Chorionic Villi Sampling↗

Prenatal diagnosis of minute supernumerary marker chromosomes.

The identification of supernumerary marker chromosomes (SMC) at prenatal diagnosis is problematic, particularly for the prediction of phenotype. The assessment of phenotypic risk is based on the size, morphology and origin of the SMC. Fluorescence in situ hybridization (FISH) characterization and family studies are also employed to aid in determining the significance of a prenatally ascertained SMC. Generally, SMC containing euchromatin are more likely to be associated with abnormal phenotypes and SMC without euchromatin are more likely to result in normal phenotypes. The smallest of SMC, minute SMC (minSMC) appear as dot-like or centric fragments and are particularly difficult to identify and characterize. Previous empirical observations suggested that the risk of phenotypic abnormality in prenatally ascertained minSMC was < or = 5%. We identified minSMC in chorionic villus samples (CVS) or amniocytes from 11 unrelated pregnancies. The chromosomal origin of each minSMC was identified by sequential FISH analysis with chromosome-specific centromere probes. Further FISH analysis with whole chromosome paint probes was undertaken to assess each minSMC for the presence or absence of euchromatin, since the presence of euchromatin may be associated with a higher risk of abnormality. Two minSMC were shown to have euchromatin. The first, a minSMC(12) was found in CVS but not confirmed in amniocytes, indicating confined placental mosaicism. The second, a minSMC derived from chromosome 19, was associated with ultrasound abnormalities. Apart from a case with mild speech delay, the remaining minSMC cases without detectable euchromatin had a normal outcome at birth and/or on longer term follow-up. Additional FISH analyses with a telomeric repeat probe showed no signal on any of the minSMC tested, suggesting that they were ring chromosomes in structure. These data further support the concept that minSMC containing euchromatin are more likely to be associated with an abnormal phenotype, although as more data are collected, this may vary by chromosome of origin. The absence of detectable euchromatin, while not guaranteeing a normal result, is most likely to have a normal outcome. The present report and previous studies do not yet allow any significant adjustment of the empirical < or = 5% risk estimate for minSMC identified at prenatal diagnosis. However, reporting of additional cases with characterization of the minSMC and particularly with long-term follow-up will, in time, allow for more accurate risk estimates and provide prognostic information.

Adult↗

Increased risk for transverse digital deficiency after chorionic villus sampling: results of the United States Multistate Case-Control Study, 1988-1992.

Although numerous infants have been reported with transverse limb deficiencies after their mothers had undergone chorionic villus sampling (CVS), it has been unclear whether the procedure caused these defects. We report the results of the first multistate case-control study to assess and quantify the risk for specific limb deficiencies associated with CVS. Case subjects were 131 infants with nonsyndromic limb deficiency ascertained from 7 population-based birth defect surveillance programs, and born from 1988-1992 to mothers 34 years of age or older. Control subjects were 131 infants with other birth defects. We ascertained exposure to CVS from medical records and maternal and physician questionnaires. We assessed rates and timing of exposure to CVS, and estimated relative and absolute risks for anatomic subtypes of limb deficiency. The odds ratio for all types of limb deficiency after CVS from 8-12 weeks' gestation was 1.7 (95% confidence interval, 0.4-6.3). For specific anatomic subtypes, the strongest association was for transverse digital deficiency (odds ratio = 6.4; 95% confidence interval, 1.1-38.6). The risk for transverse digital deficiency increased with earlier gestational exposure (P < 0.01 for trend). We estimated that the absolute risk for transverse digital deficiency in infants after CVS was 1 per 2,900 births (0.03%). Exposure to CVS was associated with a sixfold increase in risk for transverse digital deficiency. The causality of this association is supported by its strength, specificity, biologic plausibility, and consistency with the results of previous studies. Although some centers already inform patients about risk for limb deficiency, this study quantifies the magnitude of risk associated with CVS from 8-12 weeks' gestation.

Case-Control Studies↗

Fetal cell detection in maternal blood: a study in 236 samples using erythroblast morphology, DAB and HbF staining, and FISH analysis.

A protocol to detect fetal nucleated red blood cells (NRBCs) was tested in 217 pregnant women and in 19 nonpregnant controls. All the pregnant women were sampled after chorionic villus sampling (CVS); 20 were also sampled pre-CVS. NRBC recognition was based upon morphology by using staining of hemoglobin with 3,3-diaminobenzidin (DAB) or by immunocytochemical staining for fetal hemoglobin (HbF). This was combined with FISH analysis for both the X- and Y-chromosomes on the same cells. Progressive refinement of the methods increased the number of cases where NRBCs were detected from 53% (DAB) to 75% and 78% for DAB and HbF staining, respectively, with on average 43 NRBCs (range, 1-220). DAB gave a slightly higher yield than HbF in the lower cell count range (<25). In 6 out of 18 controls, NRBCs were detected with DAB, vs. 1 out of 19 (5%) with HbF. FISH analysis in 41 cases resulted in correct sex prediction in 80% (DAB) and 89% (HbF), respectively. Our data demonstrated an increase of cases with NRBCs (30% to 75%), as well as a rise of the mean number of NRBCs (6 to 29 cells), after CVS. We conclude that DAB staining is a straightforward way to screen for the presence of NRBCs in maternal blood, but is not specific for NRBCs of fetal origin. HbF immunophenotyping is a reliable marker for fetal NRBCs, which detected slightly fewer NRBCs than DAB-staining, but improved sex prediction and significantly reduced false-positive results. CVS at 10-13 weeks of gestation causes a significant increase of NRBCs in maternal blood. These data indicate that further refinement of NRBC detection is needed before application of noninvasive prenatal diagnosis using maternal blood is feasible.

Chorionic Villi Sampling↗

Chorionic villus sampling and transverse digital deficiencies: evidence for anatomic and gestational-age specificity of the digital deficiencies in two studies.

Several but not all studies indicate that chorionic villus sampling (CVS) is associated with an increased risk for transverse limb deficiencies, including digital deficiencies. It has been suggested that variations in results regarding the transverse digital deficiencies (TDDs) may be due to the use of different classification criteria. We present the combined analysis of two case-control studies, the U.S. Multistate CVS (US) study and the Italian Multicentric Birth Defects (IP-IMC) study, using two different definitions of TDDs. We compared the frequency of CVS exposure in control infants with that among those infants with any number of affected digits (any TDD), and those with all five digits of at least one limb affected (extensive TDDs). The estimated relative risk (RR) for any TDD following CVS was 10.6 (IPIMC) and 6.6 (US). For the extensive TDDs, the RR was 30.5 (IPIMC) and 10.7 (US). In both studies, extensive TDDs were less than 25% of all TDDs. Compared to all TDDs, extensive TDDs were more likely to occur after CVS performed earlier in the first trimester (before 10-11 weeks' gestation). These findings suggest a relationship between the timing of CVS and the severity of TDDs; indicate that using a restrictive definition of TDDs (all five digits affected) may limit the ability to evaluate the association between CVS and TDDs in populations in whom CVS is usually performed at or after 10 weeks' gestation; and highlight the necessity to consider gestational age in any evaluation of the relative risk for limb deficiencies associated with CVS.

Adult↗

First-trimester growth restriction and fetal aneuploidy: the effect of type of aneuploidy and gestational age.

OBJECTIVE: Our purpose was to determine the effect of type of aneuploidy and gestational age on first-trimester fetal growth. STUDY DESIGN: Crown-rump length measurement was obtained in pregnancies undergoing chorionic villus sampling in three large prenatal diagnosis centers. One hundred forty-four aneuploid fetuses, from 9 to 13 weeks' gestation, were compared with 440 matched control fetuses for evidence of crown-rump length shortening. Shortening was defined by the observed/expected crown-rump length. Expected values of crown-rump length based on last menstrual period were obtained from regression equations generated from a separate normal group. Threshold values for aneuploidy screening were determined on the basis of receiver-operator characteristic curves. RESULTS: There was significant crown-rump length shortening in trisomy 18 compared with normal fetuses, with observed/expected values < or = 0.80 (odds ratio 13.78, 95% confidence interval 5.64 to 33.88, p < 0.000001); for trisomy 13 the observed/expected crown-rump length was < or = 0.90 (odds ratio 3.64, 95% confidence interval 1.08 to 12.96, p < 0.03). There was no significant shortening of crown-rump length in Down syndrome, with observed/expected values < or = 0.92 (odds ratio 0.86, 95% confidence interval 0.50 to 1.47, p = 0.6). With shortened crown-rump length (observed/expected value < 0.86) the risk of any aneuploidy is increased (odds ratio 2.52, 95% confidence interval 1.6 to 3.96, p < 0.0001). When the first-trimester crown-rump length was shortened by > or = 14 mm, the aneuploidy risk was high (odds ratio 9.04, 95% confidence interval 3.26 to 28.67, p < 0.00001). CONCLUSION: In the first trimester fetuses with trisomy 18 and 13 appear to be growth restricted, in contrast to fetuses with trisomy 21. In at-risk pregnancies crown-length that is shorter than expected significantly increase the odds that aneuploidy is present.

Aneuploidy↗

European collaborative research on mosaicism in CVS (EUCROMIC)--fetal and extrafetal cell lineages in 192 gestations with CVS mosaicism involving single autosomal trisomy.

Cytogenetic information on cells from cytotrophoblast, villus mesenchyme, and one or more fetal tissues was available for 192 gestations with mosaicism or non-mosaic fetoplacental discrepancy involving a single autosomal trisomy in the chorionic villus sample (CVS), registered in a collaborative study (EUCROMIC) during the period 1986-1994. In order to identify predictors of confined placental mosaicism (CPM), generalized mosaicism and/or uniparental disomy (UPD), distribution of the mosaic and nonmosaic aneuploid cell lines in the different fetal and extrafetal cell lineages were analyzed. Data were related to existing hypotheses on mechanisms leading to fetoplacental discrepancies and early extraembryonic cell differentiation. Trisomy 21 mosaicism was the one most frequently confirmed in the fetus. Non-mosaic trisomy 13, 18, and 21 in the villus mesenchyme indicated the presence of a trisomic cell line in the fetus proper. Non-mosaic trisomy 2, 7, and 16 in villus mesenchyme was always found with concomitant mosaic or non-mosaic trisomy in the cytotrophoblast, but was never recovered in the fetus. Mosaic trisomy 3, 7, and 20 was predominantly restricted to the cytotrophoblast, mosaic trisomy 2 to the villus mesenchyme. Trisomies 15 and 16 were most often found in both cytotrophoblast and villus mesenchyme and not in fetal cells. This supports the hypothesis that mosaicism/discrepancy for trisomies 15 and 16 results more often than for the other trisomies from trisomic zygote rescue, enhancing their risk for UPD. We recommend, due to the risk of fetal trisomy, amniocentesis in all gestations involving mosaic autosomal trisomy in villus mesenchyme. In gestations with mosaic or non-mosaic autosomal trisomy in both cytotrophoblast and villus mesenchyme we recommend, in order to exclude fetal trisomy and/or UPD, depending on the chromosome involved, further examination by amniocentesis, ultrasound and/or test for UPD. We also recommend, due to a small but not negligible risk of false negative and false positive diagnoses, not to solely use direct preparation.

Cell Lineage↗

Chorionic villus sampling: a distinctive teratogenic effect on fingers?

BACKGROUND: An increased frequency of major limb malformations, especially terminal transverse limb defects, have been described in several studies of birth defects in children who had been exposed to the prenatal diagnosis procedure known as chorionic villus sampling (CVS). Vascular disruption has been proposed as the mechanism behind the fetal effect. We postulate that this mechanism is more likely to affect one or two middle fingers, rather than all five fingers. A recent report of the frequency of defects in any or all fingers in an unexposed control population enabled us to assess whether CVS is associated with an increased frequency of defects involving one or two fingers, as well as terminal transverse limb defects. METHODS: The frequency of limb-reduction defects affecting one or more fingers or toes, including those with constriction rings and tissue loss, in published studies of 20,236 children who had been exposed to CVS was compared with the frequency in 161,252 newborn infants who had not been exposed to CVS. Children with recognized genetic disorders were excluded. RESULTS: Several aspects of the limb deficiencies were more common in the CVS-exposed infants than in unexposed controls. The former were more likely to have: 1) any type of limb deficiency involving one or more fingers (p < .001); 2) absence/ hypoplasia of two fingers (p < .001); and 3) absence/hypoplasia of all five fingers (p = .015). The absence of the distal portion of the third finger was a distinctive type of limb-reduction defect in CVS-exposed infants. CONCLUSIONS: The occurrence of deficiencies in one or two fingers, including those designated as "amniotic band deformities," are as common as terminal transverse limb defects in CVS-exposed infants, and both are much more common than in unexposed infants. The absence of the distal portion of the third finger, with tapering and stiff joints, appears to be a distinctive effect of exposure to CVS.

Child↗