Genetic amniocentesis in multiple pregnancy

Amniocentesis in Twin Pregnancies: Risk Factors of Fetal Loss

This study aims to determine if second trimester amniocentesis in twin pregnancies provides a significant independent contribution in the prediction of miscarriage or fetal loss at any stage of pregnancy. This was a retrospective cohort study of women with twin gestations booked for routine prenatal care in four fetal medicine units in Poland in the years 2010-2020. The study population included: (1) twin pregnancies that underwent amniocentesis at 16-20 weeks' gestation; (2) twin pregnancies that did not require any further testing and were followed-up routinely. Univariable and multivariable regression analysis was used to define which maternal and pregnancy characteristics provided a significant independent contribution in the prediction of miscarriage and fetal loss at any stage of pregnancy. In the study period, 2645 twin pregnancies were eligible for analysis. There were 144 cases of miscarriage defined as fetal loss of one or both twins before 24 weeks and 40 cases of intrauterine death of one or both twins after 24 weeks. A total number of 162 twin pregnancies underwent amniocentesis at 16-20 weeks' gestation. The rate of miscarriage before 24 weeks and the rate of fetal loss at any stage of pregnancy in the group that underwent amniocentesis was 10.49% and 13.58%, respectively, compared to 5.11% and 6.52% that did not undergo amniocentesis. Multivariable regression analysis showed that factors providing a significant independent contribution in the prediction of miscarriage and fetal loss at any stage of pregnancy were monochorionicity (MC), large intertwin discordance in crown-rump length (CRL), low Pregnancy Related Plasma Protein (PAPP-A) MoM and nuchal translucency (NT) above 95th centile. Amniocentesis in twin pregnancies does not provide a significant contribution in the prediction of miscarriage or fetal loss at any stage of pregnancy.

Pregnancy Loss After Amniocentesis with Double-Needle Insertions in Twin Pregnancies

The aim of this study was to determine the pregnancy loss rate of amniocentesis with double-needle insertions in twin pregnancies. This was a retrospective study of twin pregnancies who underwent amniocentesis with double-needle insertion between 2010 and 2019 at a single center. The pregnancy loss rates were recorded as single or double fetal loss before 24 weeks’ gestation and within 4 weeks after the procedure. Risk factors for pregnancy loss after amniocentesis were also assessed. A total of 678 twin pregnancies with amniocentesis were finally included. The pregnancy loss rates before 24 weeks’ gestation and within 4 weeks after the procedure were 0.9% and 1.9%, respectively. Only one fetal loss was presumed to be a direct result of the procedure. All other cases were complicated by structural or chromosomal anomalies. Twin pregnancies with abnormal ultrasound findings had a significantly higher rate of pregnancy loss with a relative risk of 4.81 (95% CI [1.03, 22.2]). Our study showed a low pregnancy loss rate after amniocentesis in twin pregnancies with double-needle insertions technique of sampling, which can help decision making in prenatal screening and diagnosis for twin pregnancies.

Performance of non-invasive prenatal testing for foetal chromosomal abnormalities in 1048 twin pregnancies

Objective

To investigate the clinical value of non-invasive prenatal testing (NIPT) to screen for chromosomal abnormalities in twin pregnancies and to provide further data on NIPT manifestations in twin pregnancies.

Materials and methods

In a 4-year period, 1048 women with twin pregnancies were voluntarily prospectively tested by NIPT to screen for chromosomal abnormalities by sequencing cell-free foetal DNA (cffDNA) in maternal plasma. Positive NIPT results were confirmed by karyotyping, while negative results were followed up 42 days after delivery.

Results

Thirteen women had positive NIPT results as follows: 2 cases of trisomy 21 (T21), 1 of trisomy 18 (T18), 7 of sex chromosome aneuploidy (SCA), 1 of microdeletion, and 2 of microduplication. Of these 13 cases, 2 were true-positive cases confirmed by foetal karyotype analysis, namely, 1 case of T21 and 1 of microdeletion. Furthermore, the remaining 11 high-risk pregnant women were confirmed as false positive by foetal karyotyping. Thus, the combined positive predictive value (PPV) of NIPT screening for chromosomal abnormalities in twin pregnancies was 15.4% (2/13). There were no false-negative case via our follow-up results.

Conclusion

Safe and rapid NIPT has a certain clinical application value; however, the PPV is limited, and the screening efficiency is not stable. Careful use should be made in the screening of chromosomal abnormalities in twin pregnancies.

Risk of fetal loss following amniocentesis or chorionic villus sampling in twin pregnancy: systematic review and meta-analysis

OBJECTIVE

To assess the rate of fetal loss following amniocentesis or chorionic villus sampling (CVS) in twin pregnancy.

METHODS

MEDLINE, EMBASE and Cochrane databases were searched for studies reporting procedure-related complications following amniocentesis or CVS in twin pregnancy. The primary outcome was the rate of procedure-related fetal loss. The secondary outcomes were fetal loss occurring before 24 weeks of gestation and fetal loss occurring within 4 weeks after the procedure. Head-to-head meta-analyses were used to compare directly each outcome, between women undergoing amniocentesis and those not undergoing amniocentesis and between women undergoing CVS and those not undergoing CVS, and to compute pooled risk differences (RD) between women exposed and those not exposed to each invasive procedure. Additionally, meta-analyses of proportions were used to estimate the pooled rates of each of the three outcomes in women undergoing amniocentesis or CVS and in controls.

RESULTS

Sixteen studies (3419 twin pregnancies undergoing and 2517 not undergoing an invasive procedure) were included. Head-to-head meta-analyses comparing directly twin pregnancies undergoing and those not undergoing amniocentesis showed a higher risk for overall fetal loss in those undergoing amniocentesis (odds ratio (OR), 1.46 (P = 0.04); RD, 0.013 (P = 0.04)), while there was no difference in the risk of either fetal loss before 24 weeks of gestation (OR, 1.59 (P = 0.06); RD, 0.010 (P = 0.11)) or fetal loss within 4 weeks after the procedure (OR, 1.38 (P = 0.3); RD, 0.003 (P = 0.8)). Overall, the pooled rate of fetal loss was 2.4% (95% CI, 1.4-3.6%) in twin pregnancies undergoing amniocentesis compared with 2.4% (95% CI, 0.9-4.6%) in those not undergoing amniocentesis. Head-to-head meta-analyses directly comparing twin pregnancies undergoing and those not undergoing CVS showed no significant difference in either overall fetal loss (OR, 1.61 (P = 0.5); RD, 0.003 (P = 0.8)) or fetal loss before 24 weeks of gestation (OR, 1.61 (P = 0.5); RD, 0.003 (P = 0.8)). Overall, the pooled rate of fetal loss was 2.0% (95% CI, 0.0-6.5%) in twin pregnancies undergoing CVS compared with 1.8% (95% CI, 0.3-4.2%) in those not undergoing CVS.

CONCLUSION

The risk of fetal loss following amniocentesis and CVS in twins is lower than reported previously and the rate of fetal loss before 24 weeks of gestation, or within 4 weeks after the procedure, did not differ from the background risk in twin pregnancy not undergoing invasive prenatal testing. These data can guide prenatal counseling for twin pregnancies undergoing invasive procedures. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Pregnancy loss after chorionic villus sampling and genetic amniocentesis in twin pregnancies: a systematic review

OBJECTIVE

To review the available evidence regarding pregnancy loss following first-trimester chorionic villus sampling (CVS) and mid-trimester genetic amniocentesis in twins.

METHODS

We searched the MEDLINE database from January 1990 to May 2011 for randomized and cohort studies reporting on the risk of pregnancy loss after first-trimester CVS performed between 9 and 14 weeks and after genetic amniocentesis performed between 14 and 22 weeks. Where appropriate, we calculated pooled proportions and relative risks with 95% CI.

RESULTS

No randomized studies were found. For CVS, nine studies fulfilled the inclusion criteria. The overall pregnancy-loss rate was 3.84% (95% CI, 2.48-5.47; n = 4). The rate of pregnancy loss before 20 weeks was 2.75% (95% CI, 1.28-4.75; n = 3) and before 28 weeks was 3.44% (95% CI, 1.67-5.81; n = 3). For amniocentesis, the overall pregnancy-loss rate was 3.07% (95% CI, 1.83-4.61; n = 4). The rate of pregnancy loss before 20 weeks was 2.25% (95% CI, 1.23-3.57; n = 2), before 24 weeks was 2.54% (95% CI, 1.43-3.96; n = 9) and before 28 weeks was 1.70% (95% CI, 0.37-3.97; n = 5). Pooled data from four case-control studies showed a higher risk (2.59% vs. 1.53%) of pregnancy loss before 24 weeks following amniocentesis (relative risk = 1.81; 95% CI, 1.02-3.19). There were no statistically significant differences in reported pregnancy loss between transabdominal and transcervical approaches, use of a single-needle system vs. a double-needle system and single uterine entry vs. double uterine entry in the CVS group. Similarly, in the amniocentesis group, there was no statistically significant difference in fetal loss between the single uterine entry vs. the double uterine entry.

CONCLUSION

In the absence of randomized studies, it is not possible to estimate accurately the excess risk following invasive procedures in twins. Currently available data show similar overall pregnancy-loss rates for both amniocentesis and CVS with the excess risk of around 1% above the background risk.

Amniocentesis in twin pregnancies: a systematic review of the literature

OBJECTIVE

Using published data, we sought to determine the amniocentesis-related loss rate in twin gestations.

METHODS

We searched the PUBMED database using keywords "amniocentesis", "twin" and "twins" to identify articles evaluating genetic amniocentesis in twin gestations published from January 1970 to December 2010. Random effects models were used to pool procedure-related loss rates from included studies.

RESULTS

The definition of "loss" varied across the 17 studies identified (Table 1). The pooled procedure-related loss rate at < 24 weeks was 3.5% (95% confidence interval [CI] 2.6-4.7) (Figure 2). Pooled loss rates at < 28 weeks (Figure 4) and to term (Figure 5) could not be calculated due to unacceptable heterogeneity of available data. Seven studies included a control (no amniocentesis) group and reported a pooled odds ratio for total pregnancy loss among cases of 1.8 (95% CI 1.2-2.7) (Figure 3). Only 1 study reported procedure-related loss rates by chorionicity (7.7% among monochorionics vs 1.4% among controls; p 0.02).

CONCLUSION

Analysis of published data demonstrated a pooled amniocentesis-related loss rate of 3.5% in twin gestations < 24 weeks. Pooled loss rates within other post-amniocentesis intervals or other gestational age windows and the impact of chorionicity on procedure-related loss rates cannot be determined from published data.

Twins: prevalence, problems, and preterm births

The rate of twin pregnancies in the United States has stabilized at 32 per 1000 births in 2006. Aside from determining chorionicity, first-trimester screening and second-trimester ultrasound scanning should ascertain whether there are structural or chromosomal abnormalities. Compared with singleton births, genetic amniocentesis-related loss at <24 weeks of gestation for twin births is higher (0.9% vs 2.9%, respectively). Selective termination for an anomalous fetus is an option, although the pregnancy loss rate is 7% at experienced centers. For singleton and twin births for African American and white women, approximately 50% of preterm births are indicated; approximately one-third of these births are spontaneous, and 10% of the births occur after preterm premature rupture of membranes. From 1989-2000, the rate of preterm twin births increased, for African American and white women alike, although the perinatal mortality rate has actually decreased. As with singleton births, tocolytics should be used judiciously and only for a limited time (<48 hours) in twin births. Administration of antenatal corticosteroids is an evidence-based recommendation.

Amniocentesis and chorionic villus sampling in twin gestations: which is the best sampling technique?

OBJECTIVE

To compare the fetal loss rate <24 weeks and the preterm premature rupture of the membranes <34 weeks' gestation according to type of invasive procedure and to sampling techniques in twins.

STUDY DESIGN

Retrospective cohort study of 204 twin pregnancies, who underwent amniocentesis (100) or chorionic villus sampling (104).

RESULTS

Fetal loss rate <4 weeks was 3.85% in chorionic villus sampling group and 4.00% in amniocentesis group (P value not significant). According to sampling technique, fetal loss rate was 4.17% (chorionic villus sampling 1 puncture), 2.70% (amniocentesis 1 puncture), 3.75% (chorionic villus sampling 2 punctures), and 4.76% (amniocentesis 2 punctures), (P values not significant). Preterm premature rupture of the membranes rate <34 weeks was 8.2% chorionic villus sampling group and 10% in amniocentesis group (P value not significant). According to sampling technique, preterm premature rupture of the membranes rate was 12.5% (chorionic villus sampling 1 puncture), 8.1% (amniocentesis 1 puncture), 6.9% (chorionic villus sampling 2 punctures), and 11.1 % (amniocentesis 2 punctures), (P values not significant).

CONCLUSION

Double entry technique does not affect significantly the outcomes evaluated, in both amniocentesis and chorionic villus sampling.

Amniocentesis for Twin Pregnancies: Is Alpha-Fetoprotein Useful in Confirming that the Two Sacs Were Sampled?

OBJECTIVE

To assess if amniotic fluid alpha-fetoprotein (AFAFP) could be useful to determine if both sacs are sampled during an amniocentesis for twin pregnancies.

METHOD

We reviewed all amniocenteses performed on twin pregnancies over a 5-year period. Inclusion criteria were restricted to pregnancies where both karyotypes and AFAFP were available on each fetus. Pregnancies complicated by fetal anomalies were excluded. The following information was obtained: maternal age, gestational age at the procedure, karyotypes, AFAFP values, pregnancy and neonatal outcome. Placental pathology reports were used to confirm chorionicity. Analysis was performed to evaluate the impact of the fetal gender and chorionicity on the AFAFP values.

RESULTS

260 pregnancies were reviewed. Mean maternal age was 36.9 years (33.6, 40.1). Gestational age at the time of the procedure was 16.2 weeks (14.5, 17.9). Complications included 1.8% of misdiagnosis (discrepancy between karyotype and gender). The difference of AFAFP values between the two fetuses was statistically larger in dichorionic pregnancies than in monochorionic gestations. Fetal gender had no influence on the AFAFP.

CONCLUSION

Amniocentesis in twin pregnancies is associated with a 1.8% risk of misdiagnosis. AFAFP can help to assess the chorionicity of a twin pregnancy. When the difference between the two values is <0.2 MoM and the chorionicity was thought to be dichorionic and the two karyotypes are similar, then failure to sample both sacs should be suspected.

Mid-Trimester Genetic Amniocentesis in Twin Pregnancy and the Risk of Fetal Loss

OBJECTIVE

To assess the rate of fetal losses in twin pregnancies undergoing genetic mid-trimester amniocentesis.

METHODS

In the first part of this investigation, a retrospective cohort study compared a group of women . 32 years old with twin pregnancies who underwent amniocentesis with a similar group unexposed to amniocentesis. Data were compiled from January 1990 to March 2004 for patients from a single institution. Pregnancies complicated by twin-to-twin transfusion syndrome, monoamniotic twins, or lethal fetal anomalies, and those treated by fetal reduction were excluded. The primary outcome was the loss of one or both fetuses prior to 24 weeks' gestation. In the second part of the investigation, a systematic review of the literature and a meta-analysis were performed.

RESULTS

In the first part of the study, data were collected for 132 women exposed to amniocentesis and 248 women not exposed to amniocentesis. There was no significant difference in the rate of fetal losses between the two groups (3.0% vs. 0.8%, P = 0.10). No losses occurred within four weeks of the procedure. In the second part of the investigation, four studies, including ours, were considered for a meta-analysis of 2026 women with twin pregnancies. Compared with women unexposed to the procedure, amniocentesis in women with twin pregnancies increased the risk of fetal losses prior to 20 to 24 weeks' gestation (odds ratio 2.42; 95% confidence intervals 1.24-4.74, P = 0.01) with an additional risk of one adverse outcome (1 or 2 fetal losses) for every 64 amniocenteses.

CONCLUSION

Genetic mid-trimester amniocentesis in twin pregnancies is associated.

Prenatal diagnosis and multiple pregnancy

The incidence of twins, triplets, and high-order multiples has increased dramatically in the last two decades secondary to greater reliance on fertility treatments and to delayed childbearing. Offspring of a multiple gestation are at increased risk for both chromosomal and structural abnormalities. Prenatal diagnosis in these patients is challenging. Options for screening tests are limited. Invasive diagnostic procedures are complex. Likewise, physicians and patients may be faced with the dilemma of deciding how to manage discordant results. The following paper will review the unique concerns associated with prenatal diagnosis in a multiple pregnancy and the current methods of prenatal screening in these patients. Invasive prenatal diagnosis will also be explored.

Invasive Genetic Diagnosis in Multiple Pregnancies

Chromosomal anomalies and mendelian diseases are more frequent in multiple gestations than in singletons. Prenatal diagnosis is recommended in multiple pregnancies whenever indicated. Invasive testing using amniocentesis or chorionic villus sampling can be performed safely. Chorionic villus sampling has a significant advantage over amniocentesis because it offers rapid karyotyping and biochemical and DNA studies at an early stage of pregnancy. Only experienced centers should perform these procedures because of the technical aspects and the expertise needed in handling discordant results.