Genetic amniocentesis after multifetal pregnancy reduction

Selective reduction in twins and multiple pregnancies

The number of multiple pregnancies has increased, mainly due to the uncontrolled use of the assisted conception techniques. Multifetal pregnancy reduction (MFPR) has been used to reduce the risks associated with these high-risk pregnancies. It is performed in the first trimester of pregnancy by transabdominal injection of potassium chloride into the fetal heart. The risk of miscarriage seems to be associated with the final number of fetuses. A review of the literature suggests that MFPR results in better pregnancy outcome, regardless of the initial number of fetuses. The reduction to a lower number of fetuses reduces fetal losses, prematurity, infant mortality and morbidity.

Multifetal pregnancy reduction and selective termination

MPR and ST are important options for patients who have multifetal pregnancies. Both procedures have been shown to be technically safe and result in acceptable pregnancy loss rates and GAs at delivery. An important caveat is that these findings are observed in centers that have vast experience performing this type of procedure and should not be generalized to all centers. The authors believe that the good outcomes reported here and elsewhere are a result of having a relatively limited number of operators adhering to a strict common protocol and that they should not be generalized to all centers. Awareness of the ethical and psychological issues aids counseling of patients and their follow-up, but more information is needed in this area. Finally, it is the authors' hope that advances in ART will decrease the need for MPR procedures in the future.

Down's syndrome screening in pregnancies after assisted reproductive techniques: an update

Assisted reproductive techniques have increased the number of pregnant women beyond the age of 35 years and the incidence of multiple pregnancies. Various non-invasive screening methods for Down's syndrome were introduced in clinical practice during the past two decades. Specific problems were encountered when these methods were applied for pregnancies achieved by assisted reproduction treatment and the aim of this review is to explore these issues and propose an adjusted methodological approach for this highly selected population. Overall, more women with assisted reproduction singleton pregnancies are found to be false-positive for Down's syndrome. This is because standard screening algorithms include maternal age. In addition, mid-trimester maternal serum screening is associated with a higher false-positive rate. This is due to changes in the feto-placental endocrinological metabolism in pregnancies achieved by assisted reproduction treatment. Ultrasound screening of Down's syndrome by means of nuchal translucency (NT) measurements at 10-14 weeks is associated with a lower false-positive rate than mid-trimester serum screening. The lowest false-positive rates reported in singleton pregnancies are observed when serum and nuchal translucency screening are combined at 10-14 weeks. In multiple pregnancies, mid-trimester maternal serum screening is of limited clinical value. Nuchal translucency measurement is among the best available and is the most efficient screening method for multiple pregnancies. This sonographical method for screening enables specific identification of those fetuses at high risk of Down's syndrome and other anomalies, and thus contributes to a better outcome. Therefore, it should be systematically performed before any fetal reduction in high-order multiple pregnancies is planned.

Twin pregnancy: the role of ultrasound in management

Determination of chorionicity is one of the most important issues in the management of twin pregnancy. Modern ultrasound equipment has made it possible to accurately assess placentation already in the first trimester with the lambda sign. With regard to prenatal diagnosis, it is important to know the chorionicity in order to calculate the risk of chromosomally abnormal fetuses. Accurate chorionicity offers the obstetricians the opportunity to observe the monochorionic twins more intensively than is required for twins with dichorionic placentation. This review gives an update of the state of the art for clinicians caring for twin pregnancies.

Multifetal pregnancy reduction

Multifetal pregnancies have increased dramatically since the introduction and improvement in assisted reproductive techniques. Multifetal pregnancy reduction (MPR) is a technique developed over the past 15 years to deal with the sequelae of higher order multiple gestations resulting from infertility treatment. With increasing operator experience, loss rates for patients undergoing MPR have declined dramatically. The present review addresses recent data on the outcomes of patients undergoing MPR, as well as recent information on the natural history of higher-order multiple gestations in individuals not undergoing MPR. New developments in this area such as the use of chorionic villus sampling before MPR, as well as MPR to a single fetus, and information on the psychological follow-up of MPR patients are also discussed.

Chorionic villus sampling before multifetal pregnancy reduction

OBJECTIVE

This study was undertaken to determine the technical feasibility and accuracy of chorionic villus sampling before multifetal pregnancy reduction and to determine whether sampling increases the pregnancy loss rate after the reduction procedure.

STUDY DESIGN

Between January 22, 1986, and January 20, 2000, a total of 1183 patients underwent first-trimester multifetal pregnancy reduction at Mount Sinai Medical Center. Chorionic villus sampling was attempted in 86 patients before the reduction procedure. Information on the technical success and accuracy of chorionic villus sampling, as well as pregnancy outcome, was collected on all patients. Pregnancy loss rates before 24 weeks' gestation in patients undergoing chorionic villus sampling before multifetal pregnancy reduction were compared with rates in patients not undergoing sampling.

RESULTS

Chorionic villus sampling was successfully completed in 85 (98.8%) of 86 patients in whom sampling was attempted. Of 166 fetuses, 165 (99.4%) were successfully sampled. Of 165 fetuses, 3 (1.8%) had karyotypic abnormalities. Sampling errors were probably made in 2 (1.2%) of 165 fetuses. Of the 73 patients who have been delivered or are beyond 24 weeks' gestation, only 1 patient (1.4%) had a pregnancy loss after the multifetal pregnancy reduction.

CONCLUSIONS

Chorionic villus sampling before multifetal pregnancy reduction is technically feasible and accurate, with an acceptably low sampling error rate. Chorionic villus sampling before multifetal pregnancy reduction appears to be safe and does not increase the risk of loss after the reduction procedure.

Amniocentesis after multifetal pregnancy reduction: is it safe?

OBJECTIVE

This report reviews the obstetric outcomes of women with multifetal pregnancy reductions who subsequently underwent elective amniocentesis.

STUDY DESIGN

Five hundred eight patients underwent multifetal pregnancy reduction at our institution. Among these, 91 patients underwent subsequent elective amniocentesis. The obstetric outcomes of all 508 patients were followed up. By means of logistic regression we evaluated several variables to determine any association with loss rate: (1) the finishing number of fetuses, (2) the number of fetuses undergoing reduction (starting number of fetuses minus the finishing number of fetuses), (3) the gestational age at reduction, (4) the maternal age at reduction, and (5) the procedure protocol. We observed that the finishing number of fetuses, the number of fetuses removed, and the procedure protocol were significantly associated with pregnancy loss rate. Women who underwent subsequent amniocentesis were compared with those who did not undergo amniocentesis. By means of multivariate conditional likelihood analysis we stratified the two groups according to the previously mentioned significant variables to compare the pregnancy loss rates.

RESULTS

Among patients who subsequently underwent elective amniocentesis the total uncorrected pregnancy loss rate was 9.0% and the early premature delivery rate was 4.5%. The number of fetuses removed, the finishing number of fetuses, and the procedure protocol were statistically significantly associated with the loss rate. The adjusted odds ratio relating amniocentesis to the pregnancy loss rate was 0.7 (95% confidence interval, 0.31.5; P =.3.)

CONCLUSIONS

The uncorrected rates of pregnancy loss and of early premature delivery among patients with multifetal pregnancy reduction who underwent subsequent amniocentesis were comparable to those of patients with multifetal pregnancy reduction who did not undergo amniocentesis.

The challenge of prenatal diagnosis in twin pregnancies

Prenatal diagnosis in multiple gestations poses unique problems. The use of screening modalities is limited, diagnostic procedures are more complicated, and the management of discordant results may be required. This article reviews work, both past and present, regarding these issues.

Second-trimester multifetal pregnancy reduction facilitates prenatal diagnosis before the procedure

OBJECTIVE

To evaluate the pregnancy outcome of selective second-trimester multifetal pregnancy reduction (MFPR) compared to first-trimester MFPR.

DESIGN

Cohort analysis.

SETTING

In Vitro Fertilization Unit, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.

PATIENT(S)

The study groups comprised 38 and 70 patients who underwent selective second-trimester MFPR (group 1) and first-trimester MFPR (group 2) at mean gestational ages of 19.7 +/- 3.3 weeks and 11.7 +/- 0.7 weeks, respectively.

INTERVENTION(S)

Ultrasonographically guided intracardiac injection of potassium chloride (KCl) solution.

MAIN OUTCOME MEASURE(S)

Pregnancy outcome and obstetric complications.

RESULT(S)

No statistically significant difference was found between group 1 and group 2 regarding mean gestational age at delivery (35.4 +/- 3.4 weeks and 35.9 +/- 3.1 weeks, respectively); mean birth weight (2,318.9 +/- 565.7 g and 2, 138.1 +/- 529.4 g); and the incidence of obstetric complications. These complications included pregnancy loss (5.2% and 15.7%), pregnancy-induced hypertension (0 and 10%), discordancy (12% and 18. 4%), intrauterine growth restriction (0 and 40%), and gestational diabetes (0% and 6%). However, the rate of all pregnancy complications was lower among second-trimester MFPR patients.

CONCLUSION(S)

Selective second-trimester MFPR is associated with favorable perinatal outcome and may facilitate detection of structural and chromosomal anomalies before the procedure and selective reduction of the affected fetus.