Maternal serum human chorionic gonadotrophin and pregnancy-associated plasma protein a,markers for fetal down syndrome at 8–14 weeks

Maternal serum levels of human chorionic gonadotrophin and its subunits (intact, α, and free βhCG) and pregnancy-associated plasma protein A (PAPP-A) were measured in 279 women between 8 and 14 weeks' gestation. This group included 23 pregnancies in which the fetus had Down syndrome (DS), diagnosed either at birth or during the second trimester (n=17) or from chorionic villus sampling (CVS) (n=6). Normal medians were determined from the 258 apparently normal pregnancies. The median levels of intact hCG (1·4 MOM) and free βhCG (2·1 MOM) were significantly raised, whereas the median level of PAPP-A (0·39 MOM) was significantly lower in the DS pregnancies when compared with the control group. Levels of αhCG were similar in both the control and the DS pregnancies. Analysis of samples taken prior to 14 weeks' gestation demonstrated that only PAPP-A (0·34 MOM) was significantly altered in DS pregnancies. However, after the exclusion of DS cases diagnosed at CVS, the median intact hCG (1·56 MOM), free βhCG (2·27 MOM), and αhCG (1·8 MOM) were all raised in DS pregnancies. This emphasizes the problem of the interpretation of biochemical markers when DS cases are diagnosed at CVS.     

Umbilical artery velocity waveforms before and after chorionic villus sampling

Because a vascular aetiology has been suggested for the limb and oromandibular defects described after chorionic villus sampling (CVS), to determine whether transabdominal (TA) CVS causes noticeable changes in umbilical artery velocity waveforms in first-trimester pregnancies, the pulsatility index (PI) of the umbilical artery was evaluated before and after TA-CVS in 175 pregnancies sampled between 10·0 and 13·0 weeks' gestation. In 139 uncomplicated pregnancies, the mean PI values (with 95 per cent confidence interval) were before TA-CVS 2·751 (2·692–2·809), after 10 min 2·723 (2·697–2·809), and after 1 h 2·781 (2·722–2·840). There were no significant changes in PI relative to the CVS procedure either in pregnancies with an abnormal result or in those ending in spontaneous abortion. Our data do not support any statistically significant change in umbilical artery PI relative to TA-CVS in first-trimester pregnancies. This procedure, despite its invasive character, does not appear to affect the feto-placental circulation.     

Increased incidence of cytogenetic abnormalities in chorionic villus samples from pregnancies established by in vitro fertilization and embryo transfer (IVF–ET)

We studied 201 pregnancies that were established by in vitro fertilization and embryo transfer (IVF–ET) and compared the frequency of cytogenetic abnormalities with that found in a large control population matched for indication group (advanced maternal age) and time of sampling. A total of 252 IVF–ET fetuses were cytogenetically analysed by either chorionic villus sampling (CVS; n = 80) or amniocentesis (n = 172). Eleven chromosome abnormalities were found in the CVS group (13·8 per cent); among them, a 45, X/46, X, dic(q11)/46, X, del(Y)(q11) mosaic that was found in an IVF pregnancy established by intracytoplasmic sperm injection (ICSI), four cases of trisomy 21, and three cases of trisomy 7 confined to the placenta. The results indicate a statistically significant three-to five-fold increase in both confined placental abnormalities (P<0·008) and true fetal chromosome anomalies (P<0·04). In the amniocentesis group, identical rates (1·7 per cent) of chromosome abnormalities were found in the IVF–ET and control groups. It is concluded that late first trimester, but not early second trimester, IVF–ET pregnancies are characterized by an increased frequency of cytogenetic abnormalities found at prenatal diagnosis.     

Confirmation of CVS mosaicism in term placentae and high frequency of intrauterine growth retardation association with confined placental mosaicism

About 2 per cent of specimens from chorionic villus sampling (CVS) analysed either on direct preparation of cytotrophoblast cells or afterculture of mesenchymal stroma reveal confined placental mosaicism (CPM), most commonly involving chromosomal trisomy. A significantly higher rate of prenatal loss (22 per cent) as well as the presence of intrauterine growth retardation (IUGR) has been reported among pregnancies with CPM. To evaluate more precisely the effect of these aneuploid cell lines confined to the placenta on intrauterine fetal growth and fetal survival, we have studied 34 term placentae from pregnancies with CPM diagnosed on CVS and confirmed identical mosaicism in 17 of these placentae. There was a direct correlation between a high number of aneuploid cells present at CVS and a high likelihood of their detection in term placenta. Also, the proportion of aneuploid cells in the mosaic term placentae correlated with that observed in CVS specimens. Among 17 gestations with confirmed CPM at delivery, there were six cases of IUGR identified, five in liveborns and one associated with intrauterine death.     

First trimester chorionic villus sampling versus mid-trimester genetic amniocentesis-preliminary results of a controlled prospective trial

This controlled prospective study assesses the relative risks of first trimester chorionic villus sampling (CVS) versus mid-trimester gentic amniocentesis (GA). CVS subjects and amnio-centesis controls were comparable with regard to several confounding variables which might influence the risk of pregnancy loss including maternal age, smoking, alcohol consumption, gestational age at study entry, and history of vaginal bleeding or poor prior reproductive outcome. The most common indication for prenatal diagnosis was advanced maternal age (n = 511). In this subgroup, spontaneous abortion (<24 weeks) occurred in 2·9 per cent of CVS subjects versus 4−3 per cent of amniocentesis controls. The sum of spontaneous and therapeutic abortions (<24 weeks) was identical (5·3 per cent) in both groups. Therefore, intervention in the CVS group (i.e., therapeutic abortion for cytogenetic abnormalities) did not influence the observed risk of pregnancy loss. Overall perinatal mortality rates were also similar in both groups. No significant differences were identified for a number of pregnancy outcome parameters including 5 min Apgar score, birth weight, body length, head circumference, gestational age at delivery, preterm delivery, fetal growth retardation, congenital malformations, and neonatal complications. Preliminary results of this controlled prospective study suggest that chorionic villus sampling carries a low and acceptable risk.     

Transverse limb reduction defects after chorion villus sampling: A retrospective Cohort study

A retrospective cohort study was performed in five Italian obstetrical centres from 1984 to 1991 in order to verify the association between chorionic villus sampling (CVS) and transverse limb reduction defects (TLRDs). TLRD rates by period of gestation at CVS were calculated, and the study's results were compared with data from the general population. Of the 3430 pregnancies for which CVS was performed, 2759 had a known outcome. The overall rate for TLRDs was 1 in 1143 CVS pregnancies, four times higher than that of the general population in Italy (1 in 4458). The rate of TLRDs was 2·9/1000 for CVS performed at 9 weeks' gestation and 1·0/1000 for CVS at 10 weeks' gestation. A scalp defect was detected in a pregnancy in which CVS was performed at 10 weeks. A high proportion of pregnancies lost to follow-up and the poor quality of the data may have affected the results. Nevertheless, our results suggest an association between CVS carried out at less than 10 weeks' gestation and TLRDs which is consistent with the findings of other studies. CVS should not be prepared at less than 10 weeks' gestation until additional evidence is obtained.     

Confined placental mosaicism in CVS and pregnancy outcome

The perinatal outcome of 26 patients with confined placental mosaicism (CPM) detected in chorionic villus sampling (CVS) who wished to continue their pregnancies was compared with that of two controls per patient matched for age and parity (n=52). There were no significant differences in birth weight or gestational age at delivery between patients with CPM and controls. There were no cases of intrauterine growth retardation (IUGR) in the CPM patients as compared with two (2/52, 3·8 per cent) in the control group (P>0·05). There was no significant increase in fetal loss between the study group (1/26, 3·6 per cent) and the controls (1/52, 1·9 per cent) (P>0·05).     

Evaluation of transcervical chorionic villus sampling with a completed follow-up of 1550 consecutive pregnancies

Data from 1550 consecutive pregnancies after first-trimester prenatal diagnosis by transcervical chorionic villus sampling (TC-CVS) are presented. The sampling efficacy was 97.8 per cent; the mean amount of collected villus tissue was 23 mg (range 5–100 mg). There were 97 affected fetuses, mainly (73.2 per cent) with a chromosomal abnormality or a male karyotype in carriers of X-linked disease. Pregnancy termination in these and four other women for social reasons resulted in 1449 continuing pregnancies. In these pregnancies, the fetal loss rate up to 28 weeks of gestation was 5.1 per cent with the highest loss rate (3.9 per cent) before 16 weeks. When relating this fetal loss rate to maternal age, this was 6.1 per cent in the advanced maternal age group (⩾36 years) against 3.1 per cent in the younger age group. In 1376 pregnancies continuing beyond 28 weeks, the perinatal mortality rate was 1.1 per cent; the percentage of non-genetic congenital anomalies was 0.9 per cent. The reproductive pattern of women at high genetic risk after CVS followed by pregnancy termination was evaluated. Within 12 months after the first CVS followed by pregnancy termination, 70 percent of women again requested CVS in a subsequent pregnancy.     

The association between alpha-fetoprotein and βhcg levels prior to and following chorionic villus sampling in cases that spontaneously miscarried

Maternal serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (βhCG) measurements taken prior to chorionic villus sampling (CVS) in 21 patients who subsequently miscarried were compared with measurements in a control group of 113 patients with uneventful pregnancies. Patients with AFP levels of 10 iu/ml or more prior to the CVS had a 4·3 times greater risk of miscarriage (95 per cent confidence interval 1·3–13·6). AFP levels obtained 1 week after the CVS in the 13 patients with late miscarriages were higher than in the control group (P = 0·06). Patients miscarrying had a greater rise in AFP (P = 0·06) and a greater fall in βhCG levels (P = 0·04) following the CVS procedure, compared with the control subjects. Each 10-unit change in the difference between AFP or βhCG levels prior to and 1 week following the CVS was associated with a significantly increased risk for late miscarriage. Elevated maternal serum AFP levels early in pregnancy and changes in AFP and βhCG levels following CVS may predict an increased risk for subsequent miscarriage.     

First-trimester maternal serum human thyroid-stimulating hormone in chromosomally normal and Down syndrome pregnancies

Maternal serum human thyroid-stimulating hormone (TSH) levels were investigated in chromosomally normal and Down syndrome pregnancies to determine whether TSH can be used as a marker for Down syndrome in the first trimester. Measurements were conducted on stored serum samples collected from 23 Down syndrome pregnancies and 115 unaffected pregnancies before chorionic villus sampling (CVS), between 9 and 11 completed weeks of pregnancy. The samples were matched for gestational age, maternal age, maternal weight and duration of storage of the serum sample. Maternal TSH concentration was slightly decreased in Down syndrome pregnancies, with a median of 0.84 multiples of the median (MoM). Maternal serum human chorionic gonadotropin (hCG) concentration was slightly elevated in Down syndrome pregnancies, with a median of 1.03 MoM. Both differences were not significant applying matched rank analysis (p=0.50 for TSH and p=0.43 for hCG). The association between TSH and hCG in unaffected pregnancies was also measured. The Spearman correlation coefficient between TSH and hCG was −0.21 which was statistically significant (p=0.02, 95% confidence interval −0.38 to −0.03). However, it was concluded that TSH is not a useful marker for distinguishing Down syndrome-affected pregnancies from normal pregnancies in the first trimester. Copyright © 2001 John Wiley & Sons, Ltd.     

Transabdominal chorionic villus sampling: Analysis of 350 consecutive cases

We report a series of 350 patients submitted to transabdominal chorionic villus sampling (CVS). A technique using two ultrasound-guided needles and a suction pump was used. In most cases, the procedure was performed between 9 and 13 weeks. Twenty-one pregnancies were selectively terminated; nine spontaneous abortions followed the procedure and one fetal loss after 28 weeks was recorded; 153 pregnancies are in progress and 169 delivered fetuses are alive and well. Transabdominal biopsy is a feasible and effective technique for CVS.     

Prenatal diagnosis of Lesch-Nyhan syndrome: Experience with three fetuses at risk

Our experience with the prenatal detection of the Lesch-Nyhan syndrome (LNS; hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency) in three fetuses at risk is reported. Enzyme activities were measured in cultured amniocytes in two pregnancies, and in tissues and cultures obtained from chorionic villus sampling (CVS) in a third pregnancy. In all tissues the specific activities of HGPRT and adenine phosphoribosyltransferase (APRT) were determined and APRT/HGPRT ratios were calculated. In addition to the enzyme assays, the rate of purine synthesis de novo was assessed in the two amniocyte cultures, and the rate of [¹⁴C]hypoxanthine incorporation into nucleotides and sensitivity to azaguanine were measured in one of the amniocyte cultures. We report the diagnosis of normal fetuses by study of amniocytes in two pregnancies and of LNS using CVS in one pregnancy. In all three cases the diagnosis was confirmed.     

Clinical and pathological factors in spontaneous abortion following chorionic villus sampling

Twenty-nine cases of spontaneous abortion following first-trimester chorionic villus sampling (CVS) were reviewed out of a series of 722 patients. Of the 29 cases, there were only four abnormal CVS results. Pathological examination was performed in 79 per cent of cases, and this did not identify any characteristic pathological feature associated with spontaneous abortion after CVS. There was no obvious difference in the pathological features following the transabdominal (TA) or the transcervical (TC) methods. The majority of miscarriages occurred within 4 weeks of the procedure, but 38 per cent of cases aborted between 7 and 14 weeks after CVS. The TC method was used in 22 patients; the TA in 6; and both methods in 1 patient. The TA method was associated with a significantly lower fetal loss rate than the TC method (TA 2 per cent, TC 9 per cent, p < 0.001).     

Follow-up of pregnancies complicated by placental mosaicism diagnosed by chorionic villus sampling

Thirty-nine (2.3 per cent) of 1724 chromosome studies from diagnostic chorionic villus samplings (CVS) done between 1983 and 1990 showed either level III (true) mosaicism (1.2 per cent) or level II (pseudo-) mosaicism (1.1 per cent) for chromosomal aneuploidy. Follow-up information on these 39 pregnancies was collected from questionnaires to families, paediatricians, and obstetricians. For all cases in which the pregnancy was continued and further testing was accomplished, the mosaicism was felt to be confined to the placenta. As compared with a control group of pregnancies evaluated by CVS with normal karyotypes, there was no increased incidence of pregnancy loss, congenital malformations, or developmental delay in the infants. Although intrauterine growth retardation occurred in several of the level III mosaic cases, adequate catch-up growth has been demonstrated.     

Randomized trial comparing first-trimester transcervical chorionic villus sampling and second-trimester amniocentesis

A total of 800 patients were randomized at the 9th to 11th week of pregnancy either for transcervical chorionic villus sampling (CVS) on the day of trial entry or for amniocentesis (AC) at the 16th week. The indication for fetal karyotyping was maternal age in 94 per cent of the cases; the mean maternal age was 39.2 years. An adequate sample was obtained in 98.3 per cent of the cases in the CVS group and in all cases in the AC group. Retesting was indicated in 3.3 per cent of the CVS cases. An abnormal karyotype was found in 6.1 per cent of the CV samples and in 4.5 per cent of the amniotic fluid samples. There was one false-positive chromosome result in both groups. Twelve (3.1 per cent) miscarriages occurred by the 22nd week of pregnancy in the CVS group in pregnancies intended to continue. No difference was seen between the groups for total fetal loss rates. The number of surviving infants in the CVS group was 92.2 per cent and in the AC group 91.7 per cent (rate difference 0.5 per cent (95 per cent confidence interval − 3.3 to 4.3)). In our study, both the diagnostic accuracy and the risk of fetal loss were equal in the CVS and AC groups.     

Genetic diagnosis by chorionic villus sampling before 8 gestational weeks: Efficiency,reliability, and risks on 317 completed pregnancies

Transabdominal chorionic villus sampling (TA-CVS) was attempted in 328 high-risk pregnancies at 6–7 weeks of gestation. Sampling was feasible in 97.7 per cent of cases; chorionic tissue specimens of more than 10 mg were obtained in 94.4 per cent ofcases at the first needle insertion and in 100 per cent after a second attempt. Fetal karyotyping succeeded in 99.4 per cent of cases, while no diagnostic failures were reported in enzymatic and DNA analyses. Fetal loss rate in the first 4 weeks after CVS was significantly higher than in the later CVS series (7.2 vs. 2.5 per cent), but 50 per cent of losses were observed within 2 weeks in cases of inviable aneuploidies. A high incidence of severe limb abnormalities (1.6 per cent) was detected in pregnancies intended to continue, confirming the aetiological role of early CVS. Unclear visualization of the placental limits and poor control of the needle path are thought to be the main reasons for the vascular disruption of the chorionic plate, and thereby hypoxic embryo tissue damage. A better selection of cases, together with high-resolution vaginal ultrasound visualization, and analytical techniques requiring a minimal amount of tissue should avoid any teratogenic effect of early CVS.     

Isochromosome 5p mosaicism at prenatal diagnosis: observations and outcomes in six cases at chorionic villus sampling and one at amniocentesis

We present six cases of 47,+i(5p)/46 mosaicism diagnosed at chorionic villus sampling (CVS), this being the first prospective series to be reported. The clinical indication in each was advanced maternal age. Further prenatal studies in four (amniocentesis, plus fetal blood sampling in one) did not show the isochromosome. In one case, subsequent amniocentesis showed 1/48 in situ colonies with the isochromosome, but fetal blood was karyotypically normal. These five pregnancies resulted in phenotypically normal livebirths; further normal follow-up reports (from age 4 months through 4 years) are noted in four of these. Analysis of placental tissue in one case confirmed the presence of the i(5p) mosaicism. In the remaining case, in which 100% of CVS cultured cells had the i(5p), the pregnancy was terminated. Fetal skin fibroblasts did not show the i(5p). Thus, in none of these six cases was true fetal mosaicism detected, nor an abnormal phenotype noted. We suggest that a 47,+i(5p)/46 karyotype, detected at CVS, may frequently reflect confined placental mosaicism. In addition, we report a case of the primary diagnosis of 47,+i(5p)/46 mosaicism at amniocentesis. The infant appeared normal at birth, but a brain malformation was subsequently identified. Copyright © 2002 John Wiley & Sons, Ltd.     

First-trimester alpha-fetoprotein screening for Down syndrome

Screening for Down syndrome and other chromosomal aneuploidies by biochemical parameters in maternal serum is well established for the second trimester. With screening as late as 16 weeks of gestation, the option of chorionic villus sampling (CVS) unfortunately is lost. In our study population, the maternal serum alpha-fetoprotein (MSAFP) concentration was determined in 2471 women in the first trimester immediately prior to CVS. Although in this sample MSAFP tended to be lower in Down syndrome (DS) pregnancies than in pregnancies with a chromosomally normal fetus, at this early gestational age neither a fixed cut-off level of 0·5 multiples of the normal median (MOM) nor one of 0·6 MOM was suitable for identifying pregnancies at higher risk for DS. This also applied to trisomy 18, although on average MSAFP in trisomy 18 pregnancies was lower than in normal and DS pregnancies.     

Comparison of chorionic villus sampling and amniocentesis: Current status of prenatal diagnosis in Japan

Data were tabulated and compared for cases involving prenatal diagnostic procedures performed in the 8 years between January 1985 and December 1992. Of a total of 2781 pregnancies, 2546 cases (91·5 per cent) were diagnosed by amniocentesis, and 235 (8·5 per cent) by chorionic villus sampling (CVS). These findings reflect the fact that amniocentesis has taken deep root as the prenatal diagnostic procedure widely acknowledged by society, whereas even the existence of CVS has yet to be generally recognized. Analysis of our clinical and laboratory results and complication rates, however, suggests that CVS is a safe and accurate alternative to amniocentesis which should and can be positively presented to all patients who are candidates for prenatal diagnosis.     

Postnatal placental confirmation of trisomy 2 and trisomy 16 detected at chorionic villus sampling: A possible association with intrauterine growth retardation and elevated maternal serum alpha-fetoprotein

Detection of trisomy 2 and trisomy 16 mosaicism through chorionic villus sampling (CVS) is not an infrequent finding. We describe here two cases, one of non-mosaic trisomy 2 and the other of high level mosaicism for trisorny 16. Amniocentesis in both cases demonstrated non-mosaic 46,XY karyotypes. Each pregnancy continued to delivery of liveborn, normal-appearing boys; both pregnancies were complicated by severe intrauterine growth retardation (IUGR). Postnatal studies of placental biopsies in both cases confirmed the original CVS findings, whereas cord blood karyotypes were normal in both boys. Both children have demonstrated adequate catch-up growth.