Transabdominal chorionic villus sampling for fetal genetic diagnosis. Technical and obstetrical evaluation of 100 cases

The transvaginal probe as a uterine manipulator: a new technique to simplify transabdominal chorionic villus sampling in cases with difficult access to the trophoblast

OBJECTIVES

To evaluate the efficacy of using the transvaginal probe to manipulate the uterus and change the position of the trophoblast, and to simplify access to the chorionic villus under difficult conditions.

METHODS

One thousand five hundred and thirty-nine procedures were performed in our centre in 1524 pregnant women from September 2006 to September 2009. In 90 of these, a difficult access to the trophoblast was observed and uterine manipulation under continuous ultrasound guidance with a double needle technique, was applied to obtain the sample. Of these, 86 samples were taken from singleton pregnancies and 4 from two bichorionic twin pregnancies

RESULTS

One thousand five hundred and thirty-nine transabdominal chorionic villus sampling (TA-CVS) procedures were conducted on 1524 pregnant women. As many as 1449 were performed without manipulation with the transvaginal probe and in 90 cases the manipulation was carried out. In 89 cases, access to the trophoblast was difficult and the uterus was manipulated, which enabled an adequate TA-CVS to be performed with a single aspiration. In one case, TA-CVS was not performed due to significant pelvic pain in a patient with a fixed, retroflexed uterus and a previous history of endometriosis.

CONCLUSIONS

Uterine manipulation with the transvaginal probe may be a useful solution in cases where TA-CVS is limited by difficult access to the trophoblast.

[First trimester fetal sex determination in maternal serum using real-time PCR]

OBJECTIVE

Fetal sex prediction can be achieved using PCR targeted at the SRY gene by analyzing cell-free fetal DNA in maternal serum. Unfortunately, the results reported to date, show lack of sensitivity, especially in the first trimester of pregnancy. Therefore, determination of fetal sex by maternal serum analysis can not replace caryotype analysis following chorionic villus sampling.

PATIENTS AND METHODS

A new highly sensitive real-time PCR was developed to detect a SRY gene sequence in maternal serum. Analysis was performed on 121 pregnant women during their first trimester of pregnancy (mean gestational age: 11.8 weeks). Among them, 61 had at least one previous male-bearing pregnancy. Results were compared to fetal sex.

RESULTS

SRY PCR analysis of maternal serum was in complete concordance with fetal sex. Among the 121 pregnant women, 61 were bearing a male fetus and 60 a female fetus No false negative results were observed. Furthermore, no false positive results results occurred although 27 women carried female fetus during the current pregnancy, had at least one previous male-bearing pregnancy.

DISCUSSION AND CONCLUSION

This study demonstrates that a reliable, non-invasive sex determination can be achieved by PCR analysis of maternal serum during the first trimester of pregnancy. This non-invasive approach for fetal sex prediction should have great implications in the management of pregnant women carriers of an X-linked genetic disorder. Prenatal diagnosis is thus performed for male fetuses only, avoiding invasive procedures and the risk of fetal loss for female fetuses.

First-trimester fetal sex determination in maternal serum using real-time PCR

Fetal sex prediction can be achieved using PCR targeted at the SRY gene by analysing cell-free fetal DNA in maternal serum. Unfortunately, the results reported to date show a lack of sensitivity, especially during the first trimester of pregnancy. Therefore, determination of fetal sex by maternal serum analysis could not replace karyotype analysis following chorionic villus sampling. A new highly sensitive real-time PCR was developed to detect an SRY gene sequence in maternal serum. Analysis was performed on 121 pregnant women during the first trimester of pregnancy (mean gestational age: 11.8 weeks). Among them, 51 had at least one previous male-bearing pregnancy. Results were compared with fetal sex. SRY PCR analysis of maternal serum was in complete concordance with fetal sex. Among the 121 pregnant women, 61 were bearing a male fetus and 60 a female fetus. No false-negative results were observed. Furthermore, no false-positive results occurred, even though 27 women carrying a female fetus during the current pregnancy had at least one previous male-bearing pregnancy. This study demonstrates that a reliable, non-invasive sex determination can be achieved by PCR analysis of maternal serum during the first trimester of pregnancy. This non-invasive approach for fetal sex prediction should have great implications in the management of pregnant women who are carriers of an X-linked genetic disorder. Prenatal diagnosis might thus be performed for male fetuses only, avoiding invasive procedures and the risk of the loss of female fetuses.

First trimester prenatal diagnosis: chorionic villus sampling

Chorionic villus sampling has been used successfully for first trimester diagnosis of genetic disorders for over 14 years. When performed between 10 and 14 weeks' gestation, it is both safe and effective in the diagnosis of fetal chromosomal, biochemical, and molecular disorders, with risks comparable to those of second trimester amniocentesis. Cytogenetic results have been confirmed to be reliable and accurate. Although confined placental mosaicism occurs in approximately 1% of cases requiring interpretation, and occasionally additional invasive testing, its finding adds additional information about perinatal outcome and can alert the practitioner to fetal genetic disorders. Earlier concerns about procedure-induced limb defects have been reduced with the accumulation of additional data, showing minimal to no risk when chorionic villus sampling is performed after 70 days of gestation. In experienced hands, it may be the procedure of choice for sampling multiple gestations. Secondary to the advantage of safe, early diagnosis, chorionic villus sampling appears to be the optimal choice for first trimester testing.

Chorionic villus sampling

Chorionic villus sampling (CVS) has been used a successful and safe first-trimester prenatal diagnostic technique for over 12 years. Developed to avoid the medical and psychological complications of later prenatal diagnosis by amniocentesis, CVS rapidly has become a primary tool for the diagnosis of fetal cytogenetic, molecular, and biochemical disorders. In addition, its development has led to an improved understanding of several biological processes, including confined placental mosaicism and uniparental disomy.

Chorionic DNA analysis for the prenatal diagnosis of familial hypercholesterolaemia

Prenatal diagnosis for familial hypercholesterolaemia (FH) was performed by using restriction fragment length polymorphisms (RFLPs) of the LDL receptor gene on chorionic villi DNA taken during the 10th week of pregnancy. Both parents were FH heterozygotes and had previously had a healthy son and an FH homozygous son. Two RFLPs were informative in this family and revealed that the fetus was unaffected by FH. At birth the child was found to have an LDL cholesterol level of 30 mg/dl and a normal LDL receptor activity in cultured umbilical cord fibroblasts. RFLP analysis on chorionic villi DNA is highly recommended for all heterozygous FH couples in whom the LDL receptor gene mutation/s is/are still to be characterized.

The risk and efficacy of chorionic villus sampling in multiple gestations

Chorionic villus sampling (CVS) in the first trimester of pregnancy provides a safe and effective method for the early prenatal diagnosis of cytogenetic abnormalities in multiple gestations. In this multicentre study involving 126 twin and 2 triplet gestations primarily at risk because of advanced maternal age, the overall success rate of obtaining an adequate villus sample from each fetus was 99.2 per cent. For women of advanced maternal age, the rate of combined losses of chromosomally normal fetuses due to spontaneous abortion, stillbirths, and neonatal deaths was 5.0 per cent, compared with a 4.0 per cent total loss rate following CVS in singleton pregnancies derived from the same population (Rhoads et al., 1989). There was a 100 per cent success rate in obtaining a cytogenetic analysis; a cytogenetic abnormality was present in five of the multiple gestations (3.9 per cent) and involved seven fetuses (2.7 per cent). There were no diagnostic errors and no cases of normal cytogenetic diagnosis followed by the birth of a cytogenetically abnormal newborn. Based on cases of XX/XY admixture, cell contamination derived either from maternal decidua or the other twin occurred in 6 of 256 samples (2.3 per cent), giving an overall estimate of the frequency of cell contamination of 4.6 per cent; these cases did not present a diagnostic problem. However, there were two cases (0.8 per cent) in which the fetal sex was incorrect, due either to complete maternal cell contamination or to the possibility that in error one twin was sampled twice.

Chorionic villus sampling: evaluation of obstetric performance

Chorionic villus sampling is frequently utilised in the Nottingham region as a means of early prenatal diagnosis of genetic problems. Its relative safety in the early antenatal period is well established but there has been some concern that perinatal mortality may be greater in the chorionic villus sampling group as compared to amniocentesis. We have in response studied our own data and report the obstetric outcome in 144 cases where the pregnancy has progressed beyond 28 weeks gestation. We have selected a procedure free control group matched for parity. We have found no significant difference in the perinatal outcome and obstetric performance and conclude that at this juncture we should continue to offer our services as chorionic villus sampling offers significant advantages in the first trimester over amniocentesis.

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.

Risks of transabdominal chorionic villus sampling before the 12th week of amenorrhea

The authors report on a series of 210 chorion villus sampling diagnoses made with a needle by the transabdominal route. The rate of fetal loss was 4.2 per cent. Placental localization was important: fetal losses were 8 per cent when the placenta was strictly posterior (transamniotic route), whereas it was only 1.6 per cent when it was not posterior. Moreover, all fetal losses occurred (apart from one at 12.5 weeks of amenorrhea) before the 12th week of amenorrhea. The authors suggest that choriocentesis by the transabdominal route should not be performed before the 12th week of amenorrhea, and that the amniotic membrane should not be disturbed before the 13th week of amenorrhea.

Transabdominal villus sampling in early second trimester: a safe sampling method for women of advanced age

Transabdominal chorionic villus sampling (TA-CVS) was performed in 707 viable singleton pregnancies to exclude chromosomal abnormalities. Maternal age ranged between 36 and 49 years (mean 37.9 years); gestational age varied between 10.2 and 18.3 weeks (mean 13.3 weeks). In 639 women (90.4 per cent), a sufficient amount of chorionic tissue (greater than or equal to 10 mg) was obtained after one needle insertion; in 66 women (9.3 per cent) two insertions were needed. An abnormal chromosome pattern was established in 19 cases (2.9 per cent). Vaginal bleeding or spotting within 28 days after TA-CVS occurred in 11 cases (1.5 per cent). The completed follow-up of 678 chromosomally normal pregnancies showed an overall fetal loss rate of 2.6 per cent before 28 weeks. The overall perinatal mortality was 0.9 per cent. When relating fetal loss to gestational age at TA-CVS, this was 6.6 per cent in women sampled before 12 weeks against only 1.8 per cent after 12 weeks. At the same time, the percentage of fetal loss occurring within 2 weeks following the procedure was 75 and 30 per cent, respectively. It is suggested that these data reflect the decline in spontaneous abortion rate during this particular period of pregnancy. It is concluded that TA-CVS is an effective procedure which, when performed after the natural decrease of fetal loss, appears to be a safe option for women of advanced maternal age.

Current method for first and second trimester prenatal diagnosis: transabdominal chorionic villi sampling

Transabdominal CVS (chorionic villi sampling) was performed in 40 patients belonging to first or second trimester of pregnancy with 97.5% success, using a double and later single needle technique with no immediate complications. Karyotyping by direct method was successful in 75% of samples thus indicating the feasibility of cytogenetic analysis using villus tissue from first and second trimesters of pregnancy. It is a safe, simple, rapid and practical method of prenatal diagnosis in first and second trimesters of pregnancy with a potentially lower risk for fetal and maternal complications.

Integration of the transabdominal technique into an ongoing chorionic villus sampling program

Data are presented on 869 patients undergoing chorionic villus sampling procedures by one of two sampling techniques: 544 by a transcervical catheter aspiration method and 325 by a transabdominal two-needle aspiration method. The transcervical approach was the only procedure used in the first 330 cases, at which time the transabdominal technique was incorporated into our program. After an initial learning curve in the first 100 procedures the transcervical fetal loss rate stabilized at 2.7%, the number of patients requiring more than one catheter insertion decreased to 11%, and tissue weights greater than or equal to 10 mg were obtained in 88% of cases. The fetal loss rate for transabdominal chorionic villus sampling was 2.6%, indicating the addition of this new method did not significantly alter the fetal loss rate. Transabdominal chorionic villus sampling had an overall success rate of 99%, with only one insertion of the guide needle required for 98% of patients. Tissue weights of greater than or equal to 10 mg were obtained in 99% of cases. These results demonstrate that the transabdominal procedure can be rapidly and effectively incorporated by an operator already experienced with transcervical chorionic villus sampling. Since several contraindications exist for either chorionic villus sampling method, the availability of both techniques at a single center greatly enhances the ability to offer first-trimester fetal diagnosis to a majority of patients.

Analysis of fetal loss after transcervical chorionic villus sampling--a review of 719 patients

Chorionic villus sampling was performed under real-time ultrasonographic direction on a study group of 719 patients from September 9, 1985, through May 5, 1988. Follow-up of 714 of these patients who would have reached 28 weeks' gestation on September 1, 1988, revealed "an unintended" abortion rate of 4.1% by 20 weeks' gestation. Nine patients had a fetal loss less than 4 weeks after the procedure; 19 had losses up to 12 weeks after the procedure and before 20 weeks' gestation. This study revealed a significantly increased risk of fetal loss with an increase in the number of catheter insertions (p less than 0.001). The risk of fetal loss after one sampling attempt was 3%, 7.8% after two attempts, and 14.3% after three attempts.

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 cent 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 for intensive CVS routine conditions.