[Ethical, legal and economic implications of chorionic villi sampling].
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In this report we present our experience based on 570 chorionic villi samplings performed by the transcervical method at 8 to 12 weeks gestation. Cytogenetic results were obtained for 551 samples, hence a failure rate of 3.33%. The previously described technique was modified by prolonging the incubation period to 48 hours. The total number of abnormalities was 26, which represents 4.71% of our sample. Of 24 chromosomal abnormalities, 21 were unbalanced and 3 were balanced of parental origin. Five discordant cases are thoroughly discussed.
Second trimester amniocentesis has traditionally been utilized for prenatal genetic diagnosis. Chorionic villi sampling (CVS) is presently offered as an alternative. The occurrence of fetomaternal bleed (FMB) during CVS could increase the rate of post sampling abortion and, additionally, be of significance in patients at risk for isoimmunization. Detection and quantitation of FMB can be accomplished by the determination of changes in maternal serum alpha-fetoprotein (MSAFP) before and after CVS.
Between November 1985 and June 1990 we performed 400 first trimester chorionic villi samplings (CVS). In the first 107 cases only transcervical CVS was performed, regardless of placental location. Later, 163 transcervical and 130 transabdominal CVS were performed, depending on placental location. Anterior and fundal placentas were approached transabdominally and posterior placentas transcervically. Multiple pregnancies were excluded. Successful results were obtained in 394 out of 400 cases. There were 5 failures in the first set of cases and 1 in the second (p < 0.05). In 14 cases (3.5%) fetuses with normal karyotypes were spontaneously aborted, 5 of these in the first period (4.7%) and 9 (3.1%) in the second. The spontaneous abortions in the second period followed transabdominal CVS in 4 cases out of 130 (3.1%) and the transcervical route in 5 cases out of 163 (3.105%). The average attempts per case in the first period was 1.44 (SD 0.66) while in the second it was 1.17 (SD 0.44, p < 0.0001) for the transcervical route and 1.06 (SD 0.2, p < 0.002) for the transabdominal route. In our experience choosing between transabdominal and transcervical CVS according to placental location is preferable to the sole use of transcervical CVS in terms of lower failure rate and fewer attempts per case. Proficiency in both techniques is mandatory for optimal results.
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The natural occurring incidence of chromosome abnormalities (ICA) and its clinical significance were investigated in 330 chorionic villi samples (CVS) from the first trimester of pregnancy. It was found that the ICACVS was 5.67 per cent (11/194) in the normal group and 11.77 per cent (16/136) in the risk group. The difference between two groups was highly significant (P less than 0.01). The result shows that the pregnant women with threatened abortion, history of spontaneous abortion and greater than or equal to 40 years old are the high-risk factors. Special attention should be paid to these cases in clinical genetic counselling and prenatal diagnosis.
For early antenatal diagnosis, chorionic villus sampling (CVS) represents a valid alternative to early amniocentesis. It gives rapid results with minimal increase in risks (miscarriage about 1.5 p. cent). The indications of CVS are therefore likely to broaden. For late antenatal diagnosis, linked to an echographic or clinical anomaly, sampling of fetal blood by funicular puncture is taking precedence over sampling of amniotic fluid. Results can be obtained easily and much more quickly at low risk (about 1 p. cent). These techniques are in no way alternatives, but rather complement one another. It is always advisable to choose with care the technique that offers the greatest information with maximum safety.
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The authors discuss their experiences from 412 chorion villus samplings, (CVS), which they have done under four and a half years since 1985. They used eight types of instruments in performing their examinations and each instrument proved to be satisfactory in the gaining of chorion villus samples, suitable for further tests. They also discuss the bacteria found most frequently in the vagina on the basis of the examination and culturing of both vaginal and cervical fluid done prior to 151 CVS examinations and the effective method with which ascending infection can be prevented. They discuss a distributional pattern of their results based on the different indications for the CVS examinations, and the outcome of each of the pregnancies after CVS. In 377 cases they did direct karyotyping, in 30 cases DNA examination and in five cases enzyme determination also occurred.
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Vaginosonography has the potential of improving not only accurate diagnosis preceeding chorionic villus sampling but also the sampling procedure itself. The vaginosonographic diagnostic landmarks of early pregnancies are the contact area between the amnion and the chorion, the insertion of the umbilical cord, the yolk sac and the decidua-trophoblast complex. The occurrence of a "Swiss-cheese-pattern" in the latter structure is a strong hint for an unfavourable outcome of early pregnancy. Vaginosonographically guided puncture is a promising approach for chorionic villus biopsy. The punturing facilities are firmly attached to the high resolution vaginal ultrasound probe. Thus, precise ultrasound-guided puncture penetrating the vaginal skin and the uterine wall in the shortest possible distance has become possible.
Short- and long-term cultures of chorionic villi obtained in the 11th week of pregnancy revealed trisomy 14. After induced abortion trisomy 14 mosaicism was established in fetal skin and umbilical cord tissue while a second long-term culture of chorionic villi exhibited a normal karyotype. The results of the pathological investigations are discussed with respect to the cytogenetic findings.
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We report our experience in first trimester antenatal diagnosis since 1984. Transcervical chorionic villus sampling (CVS) was performed in 498 pregnancies. The rate of abnormal pregnancies was 6%, the rate of chromosomal abnormalities (trisomy) in the indication group "maternal age" was 2%. The fetal loss rate (until 28 weeks) was 3.4% (17 cases), the procedure related loss plus the background loss was 2.4% (12 cases). For 92.8% of the patients a diagnosis was available after 1 CVS procedure. Ultimately an antenatal diagnosis was given to 99% of the women through a second CVS procedure or an amniocentesis or a cordocentesis. No maternal complication was observed.
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We report on 12 prenatal diagnoses performed between weeks 10 and 13 on normal women with a well-documented family history of the Martin-Bell syndrome. Seven were obligate and three were potential carriers. One male and 2 female fetuses were found to be fragile X [fra(X)]-positive. The diagnoses were confirmed in fibroblasts or lymphocytes after interruption or postnatally. In one fra(X)-negative female fetus, the analysis of linked DNA markers indicated that most probably she was a heterozygote. Reexamination after birth gave a fra(X)-positive result. Hence this was a case of a false-negative prenatal fra(X) result. The occurrence of false-negative cytogenetic results represents a common problem that limits the sensitivity of prenatal diagnostics in the Martin-Bell syndrome. A study of linked DNA markers can improve the reliability of negative cytogenetic results in first trimester prenatal diagnosis. In case of doubt, the chromosomes could be reexamined after fetal blood sampling.
The Portex catheter and the silver cannula are two of the most widely used biopsy devices for chorionic villus sampling. In a prospective randomized study we used these two devices alternatively in 168 women. Significantly more trophoblastic tissue was obtained with the silver cannula than with the Portex catheter (p less than 0.05) while significantly more failures to obtain villus tissue were recorded with the Portex cannula (8/84 with the silver cannula vs. 19/84 with the Portex cannula; p less than 0.05). In 27 cases where use of the device met with failure to obtain chorionic villi after three attempts the other instrument was then used in the same patient (combined group). Four pregnancies aborted spontaneously after the procedure (2.4%). Significantly more complications occurred in the 'combined' group (4/27 vs. 4/168, p less than 0.05). A higher yield of trophoblastic tissue is possible with the silver cannula than with the Portex catheter.