Chorionic villi sampling: clinical experience, immediate complications, and patient attitudes

Acceptance of first-trimester prenatal diagnosis for the haemoglobinopathies in Lebanon

We have interviewed 83 couples at risk for a haemoglobin disorder, mostly beta-thalassaemia, in an effort to evaluate their attitude towards first-trimester prenatal diagnosis. Most of the families had received poor education and were of low socio-economic status and more than half of the couples were not properly aware of their genetic risk. Fifty-nine per cent of the couples were definitely in favour of prenatal diagnosis, 23 per cent were uncertain at the time of the interview, and 18 per cent were opposed to such testing, because of their religious conviction against termination of a pregnancy. Another important factor which seems to influence choice was the cost of the test. Essential issues that arise from this study include the importance of a control programme adapted to particular populations, proper information and counselling, and the need for financial support in countries such as Lebanon.

Research studies in applied human genetics: a quantitative analysis and critical review of recent literature

To determine the extent to which speculations about the social, legal, and ethical implications of genetic counseling, screening, and prenatal diagnosis are being studied empirically, the substantive contents of major genetics (N = 5) and obstetrics journals (N = 2) from the years 1985-1989 were reviewed. Among the approximately 9,000 articles published, only 58 containing relevant substantive data could be identified. Data collected in a single study were reported in more than one article in at least ten cases so that these articles actually represent only 45 distinct studies. Most described investigations of the attitudes and reactions of individuals or couples who had had or been referred for genetic counseling or prenatal diagnosis. These observational studies generally employed study-specific questionnaires, many of which were apparently self-administered by respondents, to obtain data. This survey and analysis of the recent literature suggests that despite frequent editorials and other commentaries underlining the problematic nature of developments in medical genetics and calling for their investigation, the "gate-keepers" to this service continue to pay scant attention to these issues in their reported research. Innovative and interdisciplinary studies that will provide information to close the many gaps in our understanding of the consequences of developments in applied human genetics are recommended for the future.

Patients' attitudes following chorionic villus sampling

The attitudes of 190 patients who had undergone chorionic villus sampling (CVS) were assessed by means of a questionnaire. One hundred and fifty-two patients replied of whom 68 (45 per cent) were referred because of increased maternal age and in the other 84 cases the indications included previous chromosomal abnormalities, fetal sexing, DNA analysis, and biochemical analysis. One hundred and twenty-two patients had a transcervical procedure, 24 had a transabdominal, and six patients required both procedures. One hundred and forty-one patients (93 per cent) reported CVS to be a satisfactory procedure, and the same percentage thought earlier diagnosis was beneficial. Thirty-nine patients (81 per cent) reported a better experience with CVS than with a previous amniocentesis. A majority of patients (93 per cent) wished a CVS in a future pregnancy and 137 patients (97 per cent) would accept a risk of miscarriage from the procedure of twice that quoted for amniocentesis (1 per cent).

Advances in prenatal diagnosis. Social-psychological and policy issues

Chorionic villus sampling (CVS), a new technique for prenatally diagnosing chromosomal and genetic disorders, may soon replace amniocentesis. This procedure, performed by inserting a catheter through the pregnant woman's cervix or through the abdomen and removing cells from the placenta, has the advantages of being available earlier in the pregnancy than amniocentesis (at 9 to 11 weeks gestational age) and of yielding results in a shorter time. Although the medical aspects of the procedure are being investigated, its psychosocial and policy implications have not been studied systematically. These issues include the subjective assessment of risk that prompts women to choose or to reject CVS, the implications of earlier diagnosis for feelings about abortion, the potential of negative findings (i.e., the absence of the designated disorder) for well-being during the remainder of the pregnancy, the ramifications of first trimester identification of fetal sex, equity of access to prenatal diagnosis, and the possible over-utilization of these procedures. Drawing on previous research regarding amniocentesis and more recent research concerning CVS, this article discusses the potential implications of CVS.

To what extent would women prefer chorionic villus sampling to amniocentesis for prenatal diagnosis?

Sixty-six pregnant women and 46 doctors were interviewed about their preferences for chorionic villus sampling (CVS) or amniocentesis for prenatal diagnosis in a hypothetical situation where the indication was late maternal age. The standard gamble method was used to calculate each individual's degree of preference for one procedure over the other (utility) expressed in terms of the risk of miscarriage associated with the preferred procedure that would be tolerated in order to have that procedure. Utilities for each group were calculated and compared. Pregnant women nominated a median utility for CVS of a miscarriage rate of 0.9%, while doctors nominated a median utility for CVS of a miscarriage rate of 1.2%. The difference between these utilities was not statistically significant. The method described in this study can enable potential consumers of a new procedure to provide the minimum 'clinically important difference' between a new procedure and an existing procedure necessary for calculation of the sample size in a controlled clinical trial.

Bleeding as a consequence of chorion villus sampling

A series of 4 separate studies were conducted to assess the incidence and short term consequence of bleeding associated with chorion villus sampling. Results support previous reports that risk of foetal-maternal transfusion as suggested by a rise in maternal serum alpha-fetoprotein (MSAFP) can occur. This occurrence is not consistent and need not be obvious even after therapeutic abortion. It is also transient and did not complicate mid-trimester neural tube screening or subsequent course of pregnancy. Eighty-seven percent of blood contaminating villus samples are of maternal origin. Following diagnosis 37% of patients reported some vaginal bleeding. This is mainly in the form of spotting which did not preclude normal pregnancy. Foetal loss occurred in 4 of the patients when bleeding considered heavier than spotting continued. In rhesus negative patients prophylactic anti-D gamma-globulin is advised, since neither Kleihauer counts nor MSAFP estimation reliably detect all foetal-maternal transfusions.

Prenatal diagnosis and the Canadian collaborative randomized trial of chorionic villi sampling: the physician's view

Women eligible for the Canadian randomized trial of chorionic villi sampling (CVS) often cite physician influence as a reason for refusing to participate. To measure directly physicians' attitudes to and knowledge of prenatal diagnosis (PND), amniocentesis, CVS, randomized trials, and the Canadian trial, a 3-page questionnaire was mailed to all registered obstetricians in British Columbia (BC) and in Montreal (Mtl). The overall response rate was 70%. Most physicians thought PND was important and that it was their role to discuss and advise PND to their patients. Physicians were split in their preferences for amniocentesis or CVS (32% vs. 34%); reasons for their preferences paralleled those given by women studied previously by us. Physicians who thought CVS was too experimental, who were hesitant about the trial or who were less likely to discuss the study with patients were older, less likely to have participated in a randomized trial previously and less comfortable with randomization and discussing uncertain risks with patients. Mtl physicians were less aware and more hesitant about the Canadian trial than those in BC. Moreover, Mtl physicians were more likely to consider the ongoing trial inappropriate and too experimental than BC physicians. Because physicians act as "gatekeepers," educating them about new technologies and about randomized studies is essential for ensuring both participant's access to a new procedure and success of the randomized trial.

Measurements of placental, decidual, and fetal proteins before and after chorionic villus sampling

Circulating placental [human chorionic gonadotrophin (hCG), Schwangerschafts protein 1 (SP1), pregnancy-associated plasma protein A (PAPP-A), decidual (pregnancy protein 12 (PP12), and fetal alphafetoprotein (AFP)] proteins were measured immediately before and within 1 h in 18 women undergoing diagnostic chorionic villus sampling (CVS) in the first trimester. An elevation of serum AFP levels was consistently seen, while fluctuations in excess of 10 per cent of the pre-CVS levels of SP1 and PP12 were seen in the majority of patients. Fluctuations in hCG and PAPP-A were consistently less than 10 per cent of pre-CVS values. Post-CVS changes in levels were not apparently associated with any feature of the technique, the pregnancy, or its outcome (one missed abortion). As feto-maternal haemorrhage is a common event, anti-D should be offered to rhesus-negative women undergoing CVS. In the prediction of subsequent miscarriage, only hCG and PAPP-A measurements should be considered.

Feto-maternal transfusion after chorionic villus sampling. Evaluation by maternal serum alphafetoprotein measurement

The alphafetoprotein (AFP) concentration in maternal serum was determined before and after chorionic villus sampling (CVS). A significant increase of 20% or more in the pre-CVS level was noted immediately after sampling in 59% of 837 pregnancies indicating some degree of feto-maternal haemorrhage. The increase in the AFP concentration in maternal serum was correlated with the weight of the tissue sample but not with the number of sampling attempts. A correlation of AFP increase and frequency of spontaneous abortions following CVS was suggested only in the group with an AFP increase of more than 100% or with a continuing rise in the first hour following CVS. CVS in early pregnancy obviously did not interfere with maternal serum AFP screening for neural tube defects in the second trimester. Although AFP measurement before and after CVS seems to have no immediate diagnostic application, in the research phase of CVS it may help to identify those procedures that are the least traumatic.

Prenatal diagnosis of congenital non-bullous ichthyosiform erythroderma (lamellar ichthyosis)

We report the first positive prenatal diagnosis of congenital non-bullous ichthyosiform erythroderma or lamellar ichthyosis. Fetal skin samples were obtained by fetoscopy at 21 weeks' gestation and examined by light and electron microscopy. Light microscopy revealed a thickened interfollicular epidermis with multiple layers of flattened cells and excessive keratinization of the epidermal lining of the follicular infundibulum. Electron microscopy of the thickened epidermis revealed granular cells that contained larger-than-normal keratohyalin granules and multiple layers of parakeratotic cornified cells. Although there was regional variation in the degree of interfollicular keratinization, follicles from all regions showed greater and more complete keratinization, indicating that they express the abnormality early enough in development to permit prenatal diagnosis at about 20 weeks' gestation.

First trimester chorionic villi sampling and direct chromosome preparations

Chorionic villi sampling was performed on 52 patients prior to elective termination of their pregnancies. Villi were obtained in 42, and direct chromosome preparations were successful in 41 of them. The use of a mixture of 0.075 M potassium chloride and 1% sodium citrate in the ratio of 2:1 for hypotonic treatment and 40% acetic acid for cell dispersal yielded chromosomes with good morphology and G-bands.

The Role of Ultrasound in Chorionic Villus Sampling

The use of ultrasound as a guidance tool for chorionic villi sampling for prenatal diagnosis in the first trimester is discussed. Three sampling techniques used in the first trimester are reviewed: endoscopy, blind aspiration, and the combination of endoscopy and aspiration with ultrasound guidance. A review of the literature found that ultrasound guidance provided the highest success rate in obtaining chorionic villi for chromosomal analysis and enzyme determination. Concerns regarding proper scanning technique for localizing the implantation site for sampling are discussed.

Cytogenetic analysis of chorionic villi: a technical assessment

Eighty-five samples of chorionic villi from women undergoing prenatal diagnosis at 8 to 12 weeks' gestation were subjected to cytogenetic analysis. Samples were prepared by a direct technique that permits limited analysis within two hours and by a short-term culture technique that permits detailed structural analysis within one week. An adequate number of cell divisions for cytogenetic analysis was obtained from 96% of living fetuses. Using both the direct technique and short-term culture, satisfactory banded chromosomal preparations were made in 93% of cases. Eleven of 12 pregnancies (92%) shown by ultrasound to be dead shortly before sampling, had cytogenetic abnormalities. Further studies are needed to develop banding definition equivalent to that available on cultured amniocytes.

Chorionic villus sampling. Clinical experience in 50 diagnostic cases

The results of 50 diagnostic chorionic villus samplings (CVS) are presented. In all but 2, the fetus was at risk of a chromosomal abnormality. Sampling was successful in 48 cases. One patient aborted 4 days after the procedure. Two patients had missed abortions diagnosed on ultrasound 44 and 56 days after CVS. Seven patients elected to have their pregnancies terminated. All samplings were undertaken with a specially designed cannula using realtime ultrasound guidance between 9 and 11 weeks of amenorrhoea. Endocervical swabs and blood for maternal serum alpha fetoprotein estimations before and after the procedure were routinely taken. All patients were notified of the results in 8 days or less except in 3 where long-term cultures were necessary. Six patients have delivered and 34 pregnancies are continuing satisfactorily.

Chorionic villi sampling: women's attitudes

To determine the acceptability of chorionic villi sampling (CVS) to women eligible for prenatal diagnosis, we undertook a survey to identify aspects of this new procedure that made it more or less preferable than amniocentesis. All women greater than or equal to 35 years scheduled for amniocentesis were asked to read some detailed descriptive material about amniocentesis and CVS, to rate the importance of the specific differences between procedures, and to indicate which procedure they would prefer, first considering each difference between them independently and then considering all the factors jointly. In the absence of precise estimates of CVS-associated risk at the time of the survey, almost equal proportions preferred amniocentesis and CVS (50.2 and 45.1%, respectively). Risk information was the most important factor to women preferring amniocentesis; the timing of the test or nature of the termination procedure was most important to those preferring CVS. In the hypothetical case where CVS was stipulated to have the same attributable risk as amniocentesis, 82% of respondents would prefer it. However, if the spontaneous abortion rate following CVS was stipulated to be 5% more than the amniocentesis risk, preferences reversed and only 22% would still prefer it. Thus, the data suggest that the ultimate acceptability of the new procedure for women over 35 years seeking prenatal diagnosis will depend on the risk associated with it and underscore the importance of ongoing trials aimed at establishing this risk.

Fetal mortality at the time of chorionic villi sampling

To estimate the background fetal loss rates among women who might be candidates for chorionic villi sampling (CVS) for prenatal diagnosis, we examined the frequency of spontaneous abortion and of non-viable fetuses in two groups of women thought to be pregnant at 8-12 weeks' gestation. Among 1519 women over 35 years given an appointment for amniocentesis 1978-1981, 9.8% had a spontaneous abortion prior to 16 weeks' gestation. For those under observation before week 12, the loss rate by 16 weeks was 15.3%. Among all 190 candidates for elective termination of pregnancy between 6 and 12 weeks' gestation, 12.6% were found to have a non-viable fetus at the scheduled date of abortion. The frequency of non-viability was 14% among those seen before week 12. The data suggest that the background loss rate between the time of CVS and the time of amniocentesis is approximately 1-2% and is unlikely to be higher than 9%. Until randomized clinical trials of the procedure are completed we will not know how much, if at all, the loss rate associated with CVS is increased above this background. Nevertheless, knowledge of these background risk estimates may be useful in counseling women considering participating in trials of CVS.