Chorionic villus sampling (CVS): World Health Organization European Regional Office (WHO/EURO) meeting statement on the use of CVS in prenatal diagnosis

Limb defects and chorionic villus sampling: results from an international registry, 1992-94

BACKGROUND

Several reports of limb defects occurring among infants exposed to chorionic villus sampling (CVS) during pregnancy resulted in concern about the safety of this procedure for prenatal diagnosis. To avoid publication bias and evaluate the true risk of limb defects in a CVS cohort, the World Health Organization initiated international registration of post-CVS limb defects in 1992.

METHODS

From May, 1992, to May, 1994, 77 infants or fetuses with limb defects from 138 996 pregnancies having CVS were reported to the WHO CVS Registry. These cases were analysed by standardised methods-ie, exclusion of syndromes, inherited disorders, and defects occurring in previable fetuses. The included limb deficiencies were studied by pattern analysis.

FINDINGS

Defects of the upper limbs were reported in 64.6%, of the lower limbs in 12.5%, and of both upper and lower limbs in 20.8% of cases. These figures are in agreement with the distribution of limb defects in several large population-based studies. Transverse limb defects occurred in 40.8% and longitudinal defects in 59.2%, compared with 42.7% and 57.3% in an unexposed population.

INTERPRETATION

The analysis of this cohort did not show any differences from the background population in the overall frequency or pattern distribution of limb deficiencies. There was also no correlation between gestational age at CVS and severity of defects. Therefore these results do not indicate any increased risk of limb defects after CVS.

Experience with 1251 transcervical chorionic villus samplings performed in the first trimester by a single team of operators

OBJECTIVE

We report our experience with 1251 chorionic villus samplings (CVS) performed by a single team of operators.

STUDY DESIGN

From April 1984 through August 1993, 1251 CVS were performed in 1236 pregnancies. The transcervical route was used in the vast majority and the sampling was performed during the 9th through 13th weeks of gestation in 1193 cases (96%). Follow-up was ensured to tabulate the pregnancy-related complications and fetal loss rate until 28 weeks' gestation. Pregnancy outcome was documented for all but 36 women (3%).

RESULTS

Most of the tests (72%-891/1236 pregnancies) were performed for advanced maternal age (> or = 35 years). The percentage of each indication remained relatively stable, around 90% for chromosomal indications and between 8 and 11% for DNA studies. Samples adequate for diagnosis were obtained in one or two sessions in 1179 pregnancies (95%). The rate of spontaneous abortion possibly related to CVS was 2.5% (28/1092). Mosaicism confined to the placenta was found in 23 cases (1.8%). The pregnancy outcome was known in 1098 pregnancies. There were 10 perinatal losses (0.9%) and nine congenital malformations (0.8%). No transverse limb defects were observed. The rate of premature deliveries (4.6%) and of small for gestational age were comparable to the general uninstrumented population.

CONCLUSION

CVS is a safe and effective mode of antenatal diagnosis when performed by a single team of experienced operators.

Chorionic villus sampling: quality control--a continuous improvement model

OBJECTIVE

Our purpose was to describe Vanderbilt University Medical Center's experience in establishing a chorionic villus sampling program and the importance of quality control along with a continuous improvement model on the first 1000 cases.

STUDY DESIGN

A continuous improvement model was established with emphasis on a multidisciplinary team approach and quality assurance process. A computerized data base was used for continuing analysis of complications and for allowing facile access to pertinent information.

RESULTS

A continuous improvement model allowed for an improved process and outcome for patients, personnel, and referring health care providers. Follow-up for initial symptoms after chorionic villus sampling was obtained on 98.5% of patients. Pregnancy follow-up, including birth data, was obtained on 93%.

CONCLUSION

A continuous improvement mode from the project's onset resulted in an improved process and outcome, information helpful for accessing spontaneous abortion rates and pregnancy outcomes (including the incidence of limb abnormalities and factors associated with abortions) and recommendations for training personnel.