Transvaginal chorionic villus sampling

Chorionic villus sampling (CVS) with either transcervical catheters or transabdominal needles is a widely-accepted method for prenatal diagnosis. However, there exists a small subset of patients in whom sampling is difficult or impossible with either route because of individual anatomic variations. A new method of chorionic villus biopsy has been developed to circumvent these problems, utilizing transvaginal chorionic needle aspiration guided by an intravaginal ultrasound probe. This technique was performed successfully in 15 patients in whom villi could not be obtained by either of the conventional methods. This method now makes CVS possible in essentially all women regardless of their uterine anatomy or placental placement; it may also prove useful for very early chorionic sampling.     

Chorionic villus sampling: Analysis of fetal losses to delivery,placental pathology,and cervical microbiology

A population of 1639 patients were seen for chorionic villus sampling (CVS). Embryonic death was identified at ultrasound in 5.3 per cent of patients. The number of patients undergoing CVS was 1551, with 1416 transcervical procedures and 135 transabdominal procedures. The most common indication for CVS was advanced maternal age. Spontaneous pregnancy losses identified by increased risk of pregnancy loss with increasing aspiration attempts. The total fetal loss for this population was 5.4 per cent with the pregnancy loss estimated due to procedure being 1.2 per cent. Analysis of placentae from patients having CVS and amniocen-tesis showed no differences. Microbiological assessment prior to CVS was similar to previous publications.     

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).     

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.     

Three- versus two-dimensional ultrasound for nuchal translucency thickness measurements: comparison of feasibility and levels of agreement

We have determined feasibility and levels of agreement for visualizing the nuchal translucency within a time limit with three-dimensional (3D) and two-dimensional (2D) transvaginal ultrasound. A total of 213 women of median gestational age 13 weeks (range 11–14 weeks) undergoing first-trimester nuchal translucency (NT) thickness measurements with 2D transabdominal ultrasound were included in the study. Additionally all women underwent 2D and 3D transvaginal NT examination within a time limit of 90 s. These two methods were compared with each other and with our standard method (2D transabdominal ultrasound) with respect to visualization of fetal nuchal fold and to the levels of agreement. The nuchal fold was visualized by 3D and 2D transvaginal ultrasound in 85.9% (95% CI: 80.5%, 90.3%) and 25.8% (95% CI: 20.1%, 32.2%), respectively (p<0.001). There was a statistically significant underestimation of the NT by 2D transabdominal as compared with 3D transvaginal ultrasound of 0.1 mm (p<0.001), and by 3D transvaginal as compared with 2D transvaginal ultrasound of even 0.1 mm (p<0.001). 3D transvaginal ultrasound of the nuchal fold has increased feasibility to 2D transvaginal ultrasound within a short examination time and with minimal, but significant, measurement differences. Copyright © 2001 John Wiley & Sons, Ltd.     

Transabdominal chorionic villus sampling. Clinical experience of 1159 cases

The efficacy and risks of transabdominal free-hand ultrasound-guided fine needle aspiration technique were evaluated in 1159 pregnancies submitted to chorionic villus sampling (CVS) in the first trimester and early in the second trimester. An adequate amount of chorionic tissue was obtained by two needle insertions in 99·7 per cent of cases, and a second tapping was needed in 3·5 per cent of cases. A local peritoneal reaction was the only early complication clearly related to the procedure, and it occurred in 0·3 per pent of cases without any adverse effect on the maternal and fetal outcome. The correct abortion rate in 716 consecutive concluded pregnancies was 2·4 per cent, while the rate of late obstetrical complications and perinatal mortality and morbidity compares favourably with the rates in the general population. Because of its simplicity and practicability, transabdominal aspiration is the procedure of choice and is especially recommended fonintensive CVS routine conditions.     

Prenatal detection of limb defects after chorionic villus sampling

Prenatal sonographic diagnoses of two cases of severe limb defects after first-trimester chorionic villus sampling (CVS) are presented. Pathological examination after elective termination correlated well with the prenatal sonographic findings. Although the relationship between CVS and limb defects remains controversial, careful ultrasound examination for possible limb defects in cases receiving CVS is recommended.     

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).     

Congenital malformations subsequent to chorionic villus sampling: Outcome analysis of 1048 consecutive procedures

We wished to identify the types and frequencies of malformations among continuing pregnancies exposed to chorionic villus sampling (CVS) and to determine whether selected procedure-related variables differ between the normal and anomalous cohorts. CVS was performed in 1048 patients between May 1988 and January 1992. Prospective assessment of perinatal outcome was ascertained by (1) physician—patient phone contact within 1 week of sampling, (2) ultrasound evaluation of the fetal anatomy at mid-gestation, (3) a detailed post-partum questionnaire completed by the referring obstetrician, and (4) a telephone interview with each patient after the expected date of confinement. Twenty-seven major malformations were documented among 938 pregnancies (live born, n=934; electively terminated, n=4), and included cardiac malformations (5), hypospadias (5), craniosynostosis (2), pyloric stenosis (2), inguinal hernia (2), polydactyly (2), syndactyly, distal extremely hemimelia, anencephaly, hydrocephalus, cleft lip and palate, omphalocele, diaphragmatic hernia, thanatophoric dysplasia, and unilateral cataract. Normal and anomalous cohorts were similar with respect to sampling method (transabdominal/transcervical ratio), mean gestational age at CVS, single-pass success rate, and mean total sample weight. No relationship between any procedure-related variable and the risk of malformation was observed.     

Seven cases of trisomy 3 mosaicism in chorionic villi

This paper describes seven cases of confined chorionic mosaicism with trisomy 3. The chromosomally abnormal cell line in chorionic villi was revealed in three cases at diagnostic CVS and in four cases at the evacuation of the uterine cavity after a missed abortion had been diagnosed by ultrasound. In two of these cases, the abortion occurred after apparently normal development of the fetus during the second trimester of pregnancy. An evaluation of the effect of confined chorionic mosaicism with trisomy 3 on the viability of the conceptus has been attempted.     

Chorionic villus sampling by biopsy forceps. Results of 1580 procedures from a single centre

The results of a prospective series of 1580 chorionic villus sampling (CVS) procedures using biopsy forceps are presented. Most of the procedures (1442), including 11 sets of twins, were performed by the transcervical approach (TC-CVS), using a curved-shank thin forceps, and 138 by the transabdominal approach (TA-CVS), using a trocar-guided straight thin forceps. The mean gestational age for TC-CVS was 10.9 weeks, and in 233 cases (16 per cent) the procedure was carried out between the 12th and 14th weeks. The mean gestational age for TA-CVS was 16.7 weeks. The major indication for CVS was advanced maternal age (92.7 per cent in the TC and 91.8 per cent in the TA approach), and indications for abnormal ultrasound findings were more common in the TA approach (4.5 per cent) than in TC-CVS (0.07 per cent). Although sampling was apparently accomplished in all the procedures, in 3.1 per cent of the TC-CVS and 2.2 per cent of TA-CVS procedures, the samples were less than 1 mg after dissection. A cytogenic report was obtained in 96.1 per cent of the TC-CVS and 90.6 per cent of the TA-CVS. Maternal serum alpha-fetoprotein (MSAFP) was measured before and after TC-CVS and the post-CVS MSAFP was positively correlated with the sample weight. Second-trimester amniocentesis following CVS was required in 5.2 per cent (TC-CVS) and 6.5 per cent (TA-CVS), due to the failure to obtain a cytogenetic report or diagnostic confirmation. The follow-up to the 20th week was 100 per cent by ultrasound scan, and 88.6 per cent from the 21st week to 1 week after delivery. Fetal loss rates within 2 weeks of the procedure were 1.7 per cent (TC-CVS) and 0.8 per cent (TA-CVS) and total fetal loss accumulated to 1 week after delivery was 4.6 per cent (TC-CVS) and 5.9 per cent (TA-CVS). Factors found to increase significantly fetal loss in the TC-CVS series were maternal age and the collection of very small samples, but not the number of forceps insertions.     

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.     

Transabdominal chorionic villus sampling and amniocentesis for prenatal diagnosis: 5 years' experience at a University Centre

The fetal loss rates and fetal congenital birth defects in 821 transabdominal (TA) chorionic villus sampling (CVS) and 771 amniocentesis (AC) cases were evaluated from a 5-year period (1987–1991) at the University Central Hospital of Turku. The parents were given the option of choosing between the two sampling procedures. CVS was performed, in most cases, at 11 weeks of gestation; and AC, at 15 weeks. The rate of total post-procedure loss was 6·7 per cent in the CVS group and 4·4 per cent in the AC group (p=0·08). The rate of spontaneous abortions was 1·9 per cent in the CVS group and 1·0 per cent in the AC group (p=0·10). The number of birth defects was low in both study groups. No limb reduction cases were observed. Mosaicism was noted in 14 CVS cases and in five AC cases. We conclude that TA-CVS is a safe and practical alternative to AC in prenatal fetal karyotyping.     

Intraplacental sonolucent spaces: Incidences and relevance to chorionic villus sampling

Detailed ultrasound examination of the placentae from 293 consecutive women requesting first-trimester chorionic villus sampling (CVS) showed evidence of intraplacental sonolucent spaces with varying density in 42.3 per cent of these placentae. Their presence, however, did not complicate the subsequent course of these women's pregnancies. Their prime significance relates to CVS, where inadvertent entry into these areas can lead to bleeding and contamination of the villus specimens with blood. A search for these spaces should be made before sampling, and when present, they should be avoided wherever possible.     

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.     

Cytogenetic analysis of 2928 CVS samples and 1075 amniocenteses from randomized studies

We report cytogenetic results from a randomized Danish chorionic villus sampling (CVS) and amniocentesis (AC) study including 2928 placental and 1075 amniotic fluid specimens processed in the same laboratory. The results are presented in groups comparing CVS with amniocentesis and transabdominal (TA) CVS with transcervical (TC) CVS as randomized. More abnormalities and more ambiguous diagnostic problems were found in placental tissues than in amniotic cells. There were no diagnostic errors and no incorrect sex predictions. Mosaicism was detected in 1 per cent of all cases of CVS (discordancies included). When confirmation studies were done, 90 per cent were found to be confined to the placenta. Eight cases (0.7 per cent) of mosaicism/pseudomosaicism were seen in amniotic fluid specimens, and two cases of five with confirmation studies were confirmed in the fetus. The rate of mosaicism/pseudomosaicism in CVS and AC specimens differed (P <0.05). The rate of pseudomosaicism in cultures of villi and amniotic fluid cells was 0.5 and 0.6 per cent, respectively. Single-cell aneuploidy was observed in 1.8 per cent of villi and 1.4 per cent of amniotic fluid cell specimens. Maternal cell contamination (MCC) was seen more often after TC sampling (4.5 per cent) compared with TA sampling (1.5 per cent), but posed no problems in interpretation. Compared with the processing of cultured specimens, the short-term method of preparation of villi in our laboratory doubled the technicians' workload. For practical and economic reasons we have ceased the routine use of short-term preparations.     

Randomized clinical trial of transabdominal versus transcervical chorionic villus sampling methods

The relative advantages and disadvantages of transabdominal (TA) and transcervical (TC) chorionic villus sampling (CVS) in terms of fetal risks and efficacy were evaluated in a clinical trial conducted on 1194 women randomized at 7–12 weeks' gestation. The results of the study indicate that, if any, the relative risk of fetal loss following either procedure is less than double that of the alternative technique when performed by a skilled operator. Overall, the fetal loss rate (spontaneous abortions following randomization, terminations of pregnancy, and perinatal deaths) is 16.5 and 15.5 per cent, respectively, among women allocated to TA- and TC-CVS. The two procedures are equally effective, although TA-CVS is associated with a significantly lower rate of repeat device insertions; on the other hand, a higher weight of chorionic tissue is obtained, on average, with TC-CVS. Bleeding is more common following TC-CVS, while peritoneal reaction developed only after TA-CVS. No diagnostic problems specifically related to one sampling technique were identified.     

Fumarylacetoacetase activity in cultured and non-cultured chorionic villus cells,and assay in two high-risk pregnancies

We describe further development of the fumarylacetoacetase (FAA) assay for the prenatal diagnosis of tyrosinaemia type 1 using chorionic villus sampling (CVS). We have established a reference range for FAA activity in cultured villus cells and have confirmed previously reported data on the FAA activity in uncultured chorionic villus cells. This should allow confirmation of results using CVS, without the need for further invasive procedures. We report the FAA enzyme stability at −70°C, +4°C, and at room temperature, and we have shown no obvious difference in enzyme activity with gestational age. We have analysed cultured and non-cultured CVS activity of FAA in two pregnancies at risk of tyrosinaemia type 1. In both, the fetus was designated unaffected, and these results were confirmed postnatally.     

Comparison of transabdominal and transcervical CVS and amniocentesis: Sampling success and risk

A total of 2931 women randomized to either transabdominal CVS, transceirvical CVS, or amniocentesis were studied. Unless intended or unintended abortion had occurred, they had completed up to 28 weeks of pregnancy. No significant difference was seen between total fetal loss in the transabdominal CVS group and the amniocentesis group (6.5 and 6.8 per cent, respectively, SE difference = 0.92 per cent, p = 0.01). The total fetal loss in the transcervical CVS group was 10.1 per cent. After pooling our data with data from the Canadian randomized study and the American non-randomized study, the difference in risk between trans-cervical CVS and amniocentesis was 1.8 per cent (SE difference = 0.64 per cent, p = 0.8). When the number of failed procedures and those cases evaluated as infeasible for the assigned method-for anatomical reasons-are compared, the overall sampling efficacy is poorer transcervically than transabdominally.     

Factors associated with multiple-pass procedures during chorionic villus sampling: A video analysis

Multiple placental passes during chorionic villus sampling (CVS) increase the risk of fetal loss; however, specific factors that predispose to repeat aspiration have not been delineated. To identify anatomic and technical variables associated with multiple-pass procedures, a detailed review of 205 videotaped CVS procedures (single pass = 163; multiple pass = 42) was performed, blinded to pregnancy outcome. The route of sampling did not influence the need for multiple aspiration attempts (transabdominal—30/ 135; transcervical—12/70), nor was placental location alone discriminatory. However, the combination of a posterior placenta and uterine retroversion was observed more frequently in the multiple-pass cohort (8/42 vs. 9/163; p<0.05). In transabdominal cases, suboptimal needle placement (e.g., perpendicular to the placental long axis) was more common in the initial aspiration of a multiple-pass procedure (21/30 vs. 38/105;p<0.01), while limited penetration of the catheter tip (e.g., just inside the placental edge) characterized a majority of multiple-pass cases in the transcervical subset (7/12 vs. 3/58; p<0.0001). A case-control cohort was constructed to evaluate the impact of these technical variables on sampling efficacy, independent of the influence of uterine position and placental site. In that analysis, suboptimal location and/or orientation of the sampling device remained characteristic of multiple-pass cases. We conclude that further reduction in the frequency of multiple-pass procedures might be achieved by consistent placement of the device tip in the central placental mass. Unlike amniocentesis, where any point of amnion entry will suffice, this technical nuance should be emphasized with CVS to maximize the single-pass success rate.