Chorionic villus sampling and materno-fetal transfusions: an immunological pathogenesis of vascular disruptive syndromes?

Experimental materno-embryonic transfusions with serum that is immunologically active against blood group antigens cause congenital malformations in the rat embryo. In view of the possible increased incidence of vascular disruptive syndromes after chorionic villus sampling (CVS), we investigated the occurrence of materno-fetal transfusions (MFTs) in this procedure. In 18 pregnant women experiencing two needle introductions at CVS, we looked immunohistochemically at the presence of haemoglobin A1-containing maternal erythrocytes in the fetal circulation of the separately collected first and second chorionic villus samples. In 4 of 18 patients (22 per cent), a significant increase of maternal cells was observed in the second sample compared with the first sample, indicating the occurrence of MFT by CVS. On the rare occasion of maternal immunization against fetal antigens, a CVS-associated MFT might provoke immunological damage to the fetus.

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(Y)(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.

Retrospective study of trisomy 18 in chorionic villi with fluorescent in situ hybridization on archival direct preparations.

Trisomy 18 in direct chorionic villus preparations needs further investigation since the chromosome abnormality may be confined to the placenta and may not represent the actual fetal karyotype. We performed, retrospectively, fluorescent in situ hybridization (FISH) with the chromosome 18 centromere probe (L1.84) on interphase nuclei of destained slides of all cases of full trisomy 18 (n = 22) and mosaic trisomy 18 (n = 8) detected among 7600 first-trimester chorionic villus samples during an 8-year period (1985-1992). More nuclei displaying three signals were encountered in cases of full and mosaic trisomy 18 confirmed in fetal tissue than in non-confirmed cases. FISH can be useful for the verification of trisomy 18 in direct chorionic villus preparations.

A quantitative estimation of the effect of prenatal diagnosis in dizygotic twin pregnancies in women of advanced maternal age.

Genetic counselling in a dizygotic twin pregnancy is complicated by the large number of possible pregnancy outcomes and by the conceivable differences in the parental valuation of these outcomes. We present the probability distributions of the pregnancy outcomes in dizygotic twin pregnancies for women from 35 to 45 years old without prenatal diagnosis and with transabdominal chorionic villus sampling (TA-CVS) or amniocentesis (AC), using data from the literature. TA-CVS always gives a higher probability of a favourable pregnancy outcome (the birth of one or two infants with a normal karyotype) than AC. For a 35-year-old woman, a 0.7 per cent risk of an unfavourable pregnancy outcome without prenatal diagnosis has to be weighed against the 2.1 per cent excess risk of loss of the entire pregnancy after TA-CVS. For a 45-year-old woman, a 10.2 per cent risk of an unfavourable pregnancy outcome without TA-CVS has to be balanced against a 4.4 per cent excess risk of pregnancy loss after TA-CVS. This study provides a quantitative tool for the support of individual parents with respect to the decision to undergo prenatal diagnosis in a dizygotic twin pregnancy.

Cordocentesis for rapid karyotyping in fetuses with congenital anomalies or severe IUGR.

The objective was to determine the role of percutaneous umbilical blood sampling (cordocentesis) as a rapid technique for chromosome analysis in a high risk obstetric population. Cordocentesis was attempted in 167 pregnant women (168 fetuses) with IUGR, a single anomaly or multiple anomalies. Gestational age ranged between 17 and 37 weeks. The procedure was successful in 152 (90%) fetuses with a blood sample withdrawan at first attempt in 80%. Neither technique was associated with any false negative or false positive findings. Postprocedural complications included one case of persistent fetal bradycardia, but no fetal death. In nine cases amniotic fluid was collected, resulting in 161 fetal blood or amniotic fluid samples for chromosome analysis. An abnormal chromosome pattern (n = 26) was established in 1/12 cases (8%) of severe IUGR, 6/88 cases (7%) with a single structural anomaly and 19/61 cases (31%) with multiple structural anomalies. In the presence of an abnormal chromosome pattern, the perinatal mortality rate was as high as 96%. There is a high association between multiple fetal anomalies and abnormal chromosome pattern.

Terminal transverse limb defects and early chorionic villus sampling: evaluation of 4,300 cases with completed follow-up.

Data from 4,300 consecutive cases following prenatal diagnosis by transcervical (TC) CVS (n = 1,570) and transabdominal (TA) CVS (n = 2,370) were evaluated. In the follow-up study only infants examined by a physician were included. Gestational age varied between 8.5 and 11.6 weeks (mean 10.3 weeks) for TC-CVS and between 9.3 and 20 weeks (mean 12.3 weeks) for TA-CVS 98% of TC-CVS was performed at 9-10 weeks, 80.7% of TA-CVS procedures were carried out at 12-15 weeks. Selective termination took place in 97 cases of TC-CVS (6.1%) and in 72 cases of TA-CVS (2.6%). Another 8 women had a termination for psychosocial reasons, resulting in 4,123 (1,469 TC, 2,654 TA) continuing pregnancies. The overall fetal loss rate < 28 weeks was 5.4% (n = 80) for TC-CVS and 2.6% (n = 70) for TA-CVS. The overall incidence of congenital abnormalities after birth was 0.9%. Two terminal transversal limb defects were detected in the TC-CVS group (0.14%) against one (0.04%) in the TA-CVS group.

Reproductive behaviour and prenatal diagnosis following genetic termination of pregnancy in women of advanced maternal age.

One hundred and fifty-one women of advanced maternal age who underwent genetic termination of pregnancy (TOP) were studied for their reproductive behaviour and the type of procedure for prenatal diagnosis in a subsequent pregnancy. A total of 59 women (39 per cent) had a further pregnancy. In all continuing pregnancies prenatal diagnosis was performed, of which 75 per cent consisted of chorionic villus sampling (CVS). Reproductive behaviour following a genetic termination was negatively correlated with maternal age and parity. Both reproductive behaviour and the choice to undergo a diagnostic procedure in the next pregnancy were independent of the type of diagnostic procedure in the previous affected pregnancy.

PIP: In the Netherlands, researchers studied the medical records of and followed-up on 151 women of advanced maternal age (at least 36 years old) who underwent amniocentesis or chorionic villus sampling (CVS) and elected to terminate the pregnancy due to an abnormal genetic finding (105 and 46 women, respectively) at Academic Hospital Rotterdam-Dijkzigt between January 1980 and December 1989. Researchers wanted to learn the women's subsequent reproductive behavior and determine whether the type of diagnostic procedure in the index pregnancy influenced the choice of diagnostic procedure in the next pregnancy. 61% did not experience a subsequent pregnancy. 59 women (39%) conceived again. Women who were at least 39 years old had a significantly lower subsequent pregnancy rate than 36-38 year old women (p .001). As parity increased, the subsequent pregnancy rate decreased (p = .005). 11 women experiencing a subsequent pregnancy suffered a spontaneous abortion. All of the remaining 48 women chose to undergo prenatal diagnosis again. 75% requested CVS, the prenatal diagnostic technique conducted during the first trimester of pregnancy, regardless of the technique used in the index pregnancy.

Reproductive behaviour following spontaneous loss of pregnancy after prenatal diagnosis.

One hundred and fifty-eight women of advanced maternal age with complete follow up who experienced spontaneous fetal loss after prenatal diagnosis were studied for reproductive behaviour as well as prenatal diagnosis in a subsequent pregnancy. A higher rate of subsequent pregnancies amongst women who experienced an early spontaneous abortion after chorionic villus sampling (CVS) was expected compared with women who lost a pregnancy later during pregnancy after amniocentesis. Of the 92 women who underwent CVS in a previous pregnancy, 57 (62%) became pregnant again. Of the 66 women who underwent amniocentesis in the pregnancy that ended in fetal loss, 34 women (52%) had a subsequent pregnancy. The cumulative incidence of subsequent pregnancies was significantly influenced by maternal age but not by parity or the method of prenatal testing. Most women who decided on a new pregnancy opted for prenatal diagnosis. There was a preference for amniocentesis if the patient had previously undergone CVS. However, the reverse was not the case.

Effect of chorionic villus sampling on utilization of prenatal diagnosis in women of advanced maternal age.

The effect of the introduction of chorionic villus sampling on the utilization rate of prenatal diagnosis in advanced maternal age was studied during the period 1 January 1985-1 January 1991. On the first of January 1985, the age limit for prenatal diagnosis in The Netherlands was lowered from 38 to 36 years of age. The overall uptake rate during the studied period increased significantly, but only because of the increased uptake rate in the group 36 and 37 years. In the maternal age group of 42 years and older, an uptake rate as low as 15.9% was established. This was mainly determined by the relatively high percentage (73.0%) of women from ethnic minorities in this age group. The number of CVS procedures increased significantly during the study period, but the utilization rate was not influenced, since the number of amniocenteses decreased accordingly. An increase in acceptability of prenatal diagnosis by women of advanced maternal age due to early testing and early termination of pregnancy could not be substantiated in the present study.

The risk of spina bifida aperta after first-trimester exposure to valproate in a prenatal cohort.

Use of antiepileptic drugs (AEDs) during pregnancy is associated with an increased risk of congenital malformations. Spina bifida aperta has been linked specifically to valproic acid (VPA) (estimated risk, 1 to 2%). The actual risk, the exclusive association of VPA with spina bifida and not anencephaly, and the precise causative relation remain matters of discussion. A prospective cohort study of pregnant women with epilepsy receiving AEDs and referred for prenatal diagnosis before week 22 of gestation was conducted, with follow-up to 3 months after birth. Pregnancies (291 singleton and 6 twin) in 261 women were evaluated. The prevalence of anomalies after exposure to any AED was 6.9%. For fetuses exposed to VPA, the prevalence was 9.4%, including six cases of spina bifida, two of which were in monozygotic twins (giving a prevalence rate of 6.3%, or 5.4%, if twins counted as one). Spina bifida was associated with a significantly higher average daily dose of VPA as compared with pregnancies with normal outcome (1.640 +/- 136 mg/d vs 941 +/- 48 mg/d, p = 0.0001). No relation was observed between the occurrence of spina bifida and type of maternal seizure or epilepsy, family history of epilepsy or neural-tube defects, or medical history. From these results we suggest that when the use of VPA during pregnancy cannot be avoided, the teratogenic risk might be diminished by reduction of the daily dose.

Genetic amniocentesis in twin pregnancies: results of a multicenter study of 529 cases.

To evaluate the risk of abortion after genetic amniocentesis in twin pregnancies, a retrospective study of 15 centers was performed. The spontaneous abortion rate up to 20 completed weeks of gestation was 2.3%; the abortion rate up to 28 completed weeks, as defined by WHO, was 3.7%. The abortion rate could not be correlated either with the number of needle insertions or with the type of marker dye used. There was also no correlation between the abortion rate and the gestational age at which amniocentesis was performed. A significant association was shown between congenital intestinal obstructions and the application of methylene blue intra-amniotically as a marker dye. Considering the increased natural loss rate in multiple gestations, amniocentesis in twin pregnancies seems to be a safe and reliable technique.

Origin of raised maternal serum alpha-fetoprotein levels in second-trimester oligohydramnios.

Concanavalin A (Con A) subtyping of alpha-fetoprotein (AFP) revealed higher concentrations of AFP non-reactive with Con A in sera of 12 pregnant women with second-trimester oligohydramnios and raised total serum AFP levels than in sera of 42 pregnant women with raised total serum AFP levels and a normal amniotic fluid volume. This suggests that in oligohydramnios the origin of excess AFP in the maternal compartment is amniotic fluid. It is proposed that oligohydramnios and the associated raised maternal serum AFP levels are caused by damage of the fetal membranes prior to 16 weeks of gestation resulting in leakage of amniotic fluid to the decidual tissue and resorption in the maternal circulation.

Acceptance of chorionic villus sampling in the southwest region of The Netherlands: a 5-year evaluation.

The acceptance of chorionic villus sampling (CVS) for monitoring pregnancies at risk for chromosomal and genetic disorders was studied from its introduction in the Centre for Clinical Genetics in Rotterdam in 1984 until 1988. Special attention was given to increasing acceptance in the group with advanced maternal age (AMA) (12.6% CVS in 1984, 52.2% CVS in 1988) and the group with a high genetic risk (HGR) (42.7% in 1984, 86.7% in 1988). The odds-growth-rate in CVS was 1.64 and 1.67 respectively, which was not significantly different. The relatively limited use of CVS at AMA is most likely determined by the fact that a considerable number of patients are referred too late in pregnancy to have the option of CVS.

Prenatal diagnosis in advanced maternal age. Amniocentesis or CVS, a patient's choice or lack of information?

Ninety-six women of advanced maternal age were interviewed about the way they obtained information on prenatal diagnosis and about how the decision was made as to what procedure was to be performed (transabdominal chorionic villus sampling (TA-CVS) or amniocentesis). In the CVS group, women visited their physician or midwife earlier in pregnancy (mean 7.1 weeks) than those in the amniocentesis group (mean 10.7 weeks). The availability of prenatal diagnosis was not mentioned during the first antenatal visit in 55 per cent of women from the amniocentesis group as opposed to 25 per cent from the TA-CVS group. Approximately 40 per cent of women eligible for prenatal diagnosis did not receive any information from the referring body prior to counselling at our centre. Only 29 per cent of women who underwent amniocentesis had actually chosen this procedure; 71 per cent were too late to undergo TA-CVS at 12 weeks. It is concluded that information to the patient must be improved in order to ensure early referral for prenatal diagnosis.

Transcervical (TC) and transabdominal (TA) CVS for prenatal diagnosis in Rotterdam: experience with 3611 cases.

Data from 3611 consecutive CVS (TC, N = 1780; TA, N = 1831) were analysed with emphasis put on influence of maternal and gestational age at CVS on the fetal loss rate less than 28 weeks. For TC-CVS the gestational age varied from 9.3-11.6 weeks, for TA-CVS from 9.3-20 weeks. Sampling efficacy at first attempt was 86.5 per cent and 95 per cent respectively. In 4.6 per cent an abnormal result was established. In older mothers (N = 2362) the fetal loss rate was significantly higher (p = less than 0.05) when sampled before 12 weeks (TC-CVS 6.2 per cent, TA-CVS 5.8 per cent). When the CVS (TA) was performed after 12 weeks the fetal loss rate decreased to 2.4 per cent. In 1079 younger women the fetal loss rate remained low (TC 2.8 per cent; TA less than 12 weeks 1.8 per cent; TA greater than 12 weeks 1.7 per cent) and was not influenced by gestational age at the time of sampling. We concluded both methods safe and reliable when the choice of application considers maternal age.

Interpretation of chromosome mosaicism and discrepancies in chorionic villi studies.

In 3,000 chorionic villi studies (CVS) 33 cases of mosaicism and 7 false-positive cell lines in all cells were seen. The mosaic cell lines were caused by aneuploidy of autosomes (13x), sex chromosomes (9x), and structural anomalies (11x). Mosaics of fetal origin were only 4 cases of trisomy 21 and one 47,XXY mosaic. In 7 cases abnormal karyotype of non-fetal origin was seen in all cells in direct studies, including trisomy 16 (3x) and trisomy 18 (2x). The combined use of direct CVS and cell cultures always uncovered the non-fetal origin of chromosome abnormalities and the study of cultured cells in all cases could have prevented 5 terminations. Complete follow-up studies demonstrated no false-negative results. Therefore, CVS can be nearly 100% accurate when both direct studies and cultures are examined in cases of mosaicism and other cell lines of possible non-fetal origin, such as trisomy 16, trisomy 18, translocation (21;21), and 45,X cells.

Transabdominal chorionic villus sampling in a multiple pregnancy at risk of argininosuccinic aciduria: a case report.

We report on a 32-year-old G3P2 woman at increased risk of argininosuccinic aciduria in her offspring. In her first infant, the disease was diagnosed at age 3 months. In the second pregnancy, the disorder was excluded following incorporation of radio-labeled 14C-citrulline in intact chorionic villi obtained through transcervical chorionic villus sampling at 10 weeks gestation. Twins were diagnosed in the third pregnancy. Separate transabdominal chorionic villus sampling of both fetuses was carried out at 10 weeks gestation. Chromosome analysis demonstrated a normal male and female karyotype. Incorporation of radio-labeled 14C-citrulline in intact villi was deficient in both villus samples, establishing the diagnosis of argininosuccinic aciduria in both fetuses. The present results confirm the reliability of direct analysis of villi for the diagnosis of argininosuccinic aciduria.

Spontaneous abortion rate and advanced maternal age: consequences for prenatal diagnosis.

Maternal age related and procedure-related fetal abortion rates were studied in 384 women aged 36 and over scheduled for transabdominal chorionic villus sampling (TA-CVS) at 12-14 weeks of gestation. The pre-TA-CVS abortion rate within 30 days of intake (at 6-10 weeks of gestation) rose from 1.9% at age 35-36 years to 10.9% at 40 years and older. Women entering in the 6th week of gestation had a greater probability of aborting before TA-CVS than women entering after day 48. 26 women aborted spontaneously before TA-CVS, the majority of abortions occurring at 10-12 weeks. TA-CVS was done in 346 women. 11 pregnancies were terminated because of genetic anomalies, and 8 women had spontaneous fetal loss. These findings justify delaying prenatal diagnosis in older pregnant women until 12 weeks of gestation.