Prenatal diagnosis by chorionic villus sampling

Screening and Testing in Multiples

The choice of screening or invasive procedure in twin pregnancies is a personal choice of whether the patient wishes to take a small risk of having a baby with a serious disorder versus a small risk of having a complication because she wishes to avoid that. How to interpret such risks has profound effects on the perceived value of techniques, either leading to a decision to screening or going directly to chorionic villus sampling. There are profound issues surrounding the data and the interpretation of the data. No single short review can exhaustively examine all of the issues.

Needle Steering and Motion Planning in Soft Tissues

In this work, needle insertion into deformable tissue is formulated as a trajectory planning and control problem. A new concept of needle steering has been developed and a needle manipulation Jacobian defined using numerical needle insertion models that include needle deflection and soft tissue deformation. This concept is used in conjunction with a potential-field-based path planning technique to demonstrate needle tip placement and obstacle avoidance. Results from open loop insertion experiments are provided.

Invasive diagnostic procedures in twin pregnancies

The rising rate of multiple pregnancies and its association with advanced maternal age has expanded the need for prenatal diagnosis in twins and higher order gestations. The complexity of the invasive diagnostic procedures and the risk of loss of an unaffected twin raise significant clinical, technical and ethical issues. In this review we discuss the specific issues of early scanning, counseling and determination of chorionicity prior to invasive procedures in twins. We present the available data describing the risk associated with these procedures in twins and compare data of fetal loss rate from different studies. We also discuss the issues of fetal blood sampling and late karyotyping in twin pregnancies.

Adverse pregnancy outcome following post-chorionic villus sampling amniocentesis compared to chorionic villus sampling

OBJECTIVE

To assess the adverse pregnancy outcome of post-chorionic villus sampling (CVS) amniocentesis and chorionic villus sampling.

METHODS

Adverse pregnancy outcomes of 32 post-CVS amniocentesis cases and 264 CVS only cases were compared. The base-line characteristics were comparable in the 2 groups.

RESULTS

One (3.1%) chromosomal abnormality was detected in the post-CVS amniocentesis group, compared to 5 (1.8%) in the CVS only group (p > 0.05). The fetal loss rate (spontaneous abortions and stillbirths) among continuing pregnancies was 3.2% in the post-CVS amniocentesis group and 3.5% in the CVS only group (p > 0.05). No statistically significant difference was found in the incidence of neonatal death, preterm delivery, fetal growth restriction, or congenital anomalies between the 2 groups.

CONCLUSION

Adverse pregnancy outcome occurred at a similar frequency in the post-CVS amniocentesis group as in the CVS only group. Therefore, a subsequent amniocentesis after CVS can be considered as a safe procedure that does not introduce any additional adverse pregnancy outcome compared to that of CVS only.

Abnormal karyotypes in semi-direct chorionic villus preparations of women with different cytogenetic risks

Among 3499 cytogenetically investigated semi-direct chorionic villus samples, 219 (6.3 per cent) abnormal karyotypes were encountered. The karyotypes were considered certainly abnormal (generalized abnormal with high probability) in 109 cases (3.1 per cent), and in 110 cases (3.1 per cent) uncertainly abnormal (potentially confined to the placenta), requiring further investigation. Of these 110 uncertain abnormalities, the cytogenetic result turned out to be finally abnormal representing generalized abnormality in 36 cases (32.7 per cent), finally normal representing confined placental mosaicism (CPM) in 69 cases (62.7 per cent), and remained undetermined in 5 instances (4.5 per cent). The rate of the numbers of certainly abnormal and all (certainly + uncertainly) abnormal results, the certainty rate, and that of generalized abnormalities and all abnormalities (generalized abnormalities + CPM cases), the predictive value, are strongly correlated with the cytogenetic risk. Therefore, we advise chorionic villus sampling for cytogenetic investigation only in women with a cytogenetic risk equal to or exceeding that of a 40-year-old pregnant woman. Because of the high rate of prenatal follow-up investigations after the finding of uncertain results in semi-direct villi, semi-direct and cultured villi should be karyotyped simultaneously.

Multifetal pregnancy reduction: a review of the world results for the period 1993-1996

The objective of this work was to evaluate the outcome of multifetal pregnancy reduction and to provide an analysis of the ethical dilemmas associated with its application. The study design was based on data on over 1400 completed pregnancies that underwent multifetal pregnancy reduction as reported in the world literature during 1993-1996. The results were: A total of 1453 completed cases of multifetal pregnancy reduction are presented. The total survival rate was estimated to be 87.7%, resulting in a total pregnancy loss rate of 12.3%. The lowest survival rate is found to be in higher-order pregnancies of five or more fetuses (75.2%), whereas pregnancy loss rate seems to be similar for quadruplets, triplets and twins that underwent reduction (11.3%, 8.3% and 13.6%, respectively). A 33.3% of the total pregnancy loss rate occurred within four weeks from the procedure, whereas 66.7% occurred after the four weeks but at 24 weeks of gestation or earlier. The mean gestational age at delivery was estimated to be 33 weeks for pregnancies reduced to triplets, 35.8 weeks for those reduced to twins and 36.9 weeks for singletons, with 5% delivering at less than 28 weeks and 9.6% at 29-32 weeks. We conclude that multifetal pregnancy reduction has been established as an efficient and safe way to improve outcome of multifetal gestations, especially those with four or more fetuses and likely of triplets. As the experience from the procedure increases, it seems that reduction of triplets to twins can be offered to patients with satisfactory results. The reduction to singletons has not yet been established and is being performed only when medical indications exist. Prenatal genetic diagnosis should become an integral part of counselling on multiple pregnancy. Physicians should take whenever possible measures designed to prevent high multiple birth pregnancies. We also note that although multifetal pregnancy reduction improves significantly the outcome of multiple pregnancies, several ethical dilemmas arising from its application are still under dispute.