Amniocentesis in pregnancies at or beyond 24 weeks: an international multicenter study.

BACKGROUND: Amniocentesis for genetic diagnosis is most commonly done between 15 and 22 weeks of gestation but can be performed at later gestational ages. The safety and genetic diagnostic accuracy of amniocentesis have been well-established through numerous large-scale multicenter studies for procedures before 24 weeks, but comprehensive data on late amniocentesis remain sparse. OBJECTIVE: To evaluate the indications, diagnostic yield, safety, and maternal and fetal outcomes associated with amniocentesis performed at or beyond 24 weeks of gestation. STUDY DESIGN: We conducted an international multicenter retrospective cohort study examining pregnant individuals who underwent amniocentesis for prenatal diagnostic testing at gestational ages between 24w0d and 36w6d. The study, spanning from 2011 to 2022, involved 9 referral centers. We included singleton or twin pregnancies with documented outcomes, excluding cases where other invasive procedures were performed during pregnancy or if amniocentesis was conducted for obstetric indications. We analyzed indications for late amniocentesis, types of genetic tests performed, their results, and the diagnostic yield, along with pregnancy outcomes and postprocedure complications. RESULTS: Of the 752 pregnant individuals included in our study, late amniocentesis was primarily performed for the prenatal diagnosis of structural anomalies (91.6%), followed by suspected fetal infection (2.3%) and high-risk findings from cell-free DNA screening (1.9%). The median gestational age at the time of the procedure was 28w5d, and 98.3% of pregnant individuals received results of genetic testing before birth or pregnancy termination. The diagnostic yield was 22.9%, and a diagnosis was made 2.4 times more often for fetuses with anomalies in multiple organ systems (36.4%) compared to those with anomalies in a single organ system (15.3%). Additionally, the diagnostic yield varied depending on the specific organ system involved, with the highest yield for musculoskeletal anomalies (36.7%) and hydrops fetalis (36.4%) when a single organ system or entity was affected. The most prevalent genetic diagnoses were aneuploidies (46.8%), followed by copy number variants (26.3%) and monogenic disorders (22.2%). The median gestational age at delivery was 38w3d, with an average of 59 days between the procedure and delivery date. The overall complication rate within 2 weeks postprocedure was 1.2%. We found no significant difference in the rate of preterm delivery between pregnant individuals undergoing amniocentesis between 24 and 28 weeks and those between 28 and 32 weeks, reinforcing the procedure's safety across these gestational periods. CONCLUSION: Late amniocentesis, at or after 24 weeks of gestation, especially for pregnancies complicated by multiple congenital anomalies, has a high diagnostic yield and a low complication rate, underscoring its clinical utility. It provides pregnant individuals and their providers with a comprehensive diagnostic evaluation and results before delivery, enabling informed counseling and optimized perinatal and neonatal care planning.

Amniocentesis in twin gestation: the association between gestational age at procedure and complications.

PURPOSE: Third trimester amniocentesis is often performed when indications arise after 24 weeks of gestation-typically to investigate new sonographic findings, and might be related to pre-term birth. Scarcity of data exists concerning the risks of third-trimester amniocentesis in twin pregnancies. METHODS: A retrospective cohort study of all twin gestations that underwent amniocentesis in a tertiary hospital between 2007 and 2016. Outcomes and procedure-related complications were compared between third-trimester (≥ 24 weeks) and mid-trimester amniocentesis (16-23 weeks). Primary outcome was defined as membrane rupture within four weeks of procedure. Logistic regression analysis was utilized to adjust results to potential confounders. RESULTS: Overall, 185 eligible women were included, of them, 28 (15.1%) underwent third-trimester amniocentesis and 157 (84.9%) underwent mid-trimester amniocentesis. Women in the third-trimester amniocentesis group were younger and presented higher frequencies of intra-uterine growth restriction (31.5 vs. 35.3, p < 0.001, and 28% vs. 10% p = 0.015, respectively). The prevalence of membrane rupture within 4 weeks of the procedure was significantly higher in the third-trimester amniocentesis group (31% vs. 1%, p < 0.001). Delivery rates after third-trimester amniocentesis within 1, 2 and 4 weeks of the procedure were 11%, 14.8% and 52%, respectively, versus 0% following mid-trimester amniocentesis (p < 0.001). Gestational age at delivery was similar between the groups (35.7 vs. 36.4 gestational weeks, p = 0.34). In multivariate analysis, gestational age at amniocentesis was found to be an independent risk factor for premature rupture of membranes within 4 weeks of the procedure. CONCLUSION: Third trimester amniocentesis in twin pregnancies is associated with significantly higher rates of procedure-related membrane rupture compared to mid-trimester amniocentesis.

The application of late amniocentesis: a retrospective study in a tertiary fetal medicine center in China.

BACKGROUND: To assess the indications and complications of late amniocentesis and the advanced genetic test results in a tertiary university fetal medical medicine unit. METHODS: In this retrospective study, women that underwent amniocentesis at 24+ 0 to 39+ 4 weeks, between January 2014 and December 2019, were recruited. Indications, complications, genetic test results, and pregnancy outcomes were reported for each pregnancy and compared with those who underwent the traditional amniocentesis at 16+ 0 to 23+ 6 weeks (control group). Information was retrieved from patient medical records, checked by research staff, and analyzed. RESULTS: Of the 1287 women (1321 fetuses) included in the late amniocentesis group, late detected sonographic abnormalities (85.5%) were the most common indication. The overall incidence of preterm birth and intrauterine demise after amniocentesis were 2.5 and 1.3%, respectively. Sixty-nine fetuses with aneuploidy (5.3%) and seventy-two fetuses with pathogenic copy number variations (5.5%) were identified by chromosomal microarray analysis. The maximal diagnostic yield (70%) was in the subgroup of fetuses with the abnormal diagnostic test results, followed by abnormal NIPT results (35.7%) and multiple abnormalities (23.8%). And 35.4% of the pregnancies were finally terminated. CONCLUSIONS: Due to the high detection rates of advanced genetic technologies and the safety of the invasive procedure (3.9% vs 4.0%), it is reasonable to recommend late amniocentesis as an effective and reliable method to detect late-onset fetal abnormalities. However, chromosomal microarray and whole-exome sequencing may result in uncertain results like variants of uncertain significance. Comprehensive genetic counseling is necessary.

Role of late amniocentesis in the era of modern genomic technologies.

OBJECTIVE: Traditionally, amniocentesis is performed between 17 and 23 weeks of gestation. This enables decisions regarding the course of pregnancy to be made before viability. Less frequently, amniocentesis is performed in the third trimester. Advanced genomic technologies such as chromosomal microarray analysis (CMA) provide more detailed information about the fetus compared with traditional G-banded chromosomal analysis. The aim of this study was to assess the indications for and safety of late amniocentesis, genetic-test results (especially in the context of CMA technology) and outcome of pregnancies that underwent the procedure after 24 weeks. METHODS: Medical records were analyzed retrospectively of all women in whom amniocentesis was performed at a gestational age of 24 + 0 to 38 + 6 weeks, at Hadassah Medical Center, between June 2013 and March 2017. Parameters investigated included indications for late amniocentesis, complications, CMA results and pregnancy outcome. RESULTS: During the study period, 291 women (303 fetuses, 277 singleton and 14 twin pregnancies; in two twin pairs, one fetus was terminated before amniocentesis) underwent late amniocentesis. CMA was performed in all instances of amniocentesis. The most frequent indication was abnormal sonographic finding(s) (204/303 fetuses, 67%). Preterm delivery occurred in 1.7% and 5.1% of pregnancies within the first week and within 1 month following the procedure, respectively. Aneuploidy was detected in nine (3%) fetuses and nine (3%) others had a pathogenic/likely pathogenic copy number variant, suggesting that CMA doubled the diagnostic yield of traditional karyotyping. Maximal diagnostic yield (17.5%) was achieved for the subgroup of fetuses referred with abnormal sonographic findings in two or more fetal anatomical systems. Variants of uncertain significance or susceptibility loci were found in another nine (3%) fetuses. CONCLUSIONS: In pregnancies undergoing late amniocentesis, CMA increased detection rates of fetal abnormalities and had a shorter turnaround time compared with traditional chromosomal analysis; therefore, late amniocentesis may serve as a helpful tool for detecting fetal abnormalities or reassuring parents following late-appearing abnormal sonographic findings. However, CMA may expose findings of uncertain significance, about which the couple should be precounseled. The procedure appears to be safe. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

The yield and complications of amniocentesis performed after 24 weeks of gestation.

PURPOSE: This study assessed the use and complications of late amniocentesis (AC) and analyzed factors that affect complication rate. METHODS: A retrospective analysis of 167 genetic AC performed after 24 weeks during a 10-year period in two medical centers was conducted. Data regarding the indications for AC, genetic work-up, and pregnancy outcomes were retrieved from patient medical records and telephone-based questionnaires. RESULTS: Mean gestational age (GA) at the time of AC was 31.7 ± 2.7 weeks; 104 procedures were performed at ≤32 weeks, including 24 at ≤30 weeks. The overall pregnancy complication rate occurring at any time after the procedure was 6.6% (11). Of these, 4.8% (8) occurred within a month after AC, including 2.4% (4) that occurred within a week. An additional three occurred after 30 days. There were no differences in the total complication rate and in the rate of specific complications of procedures performed at ≤32 weeks or at ≤30 weeks. Maternal age did not affect outcomes. Genetic testing was abnormal in five cases (3%). Amniocyte culture failed in 3 cases (2.3%), with no technical failures in 52 chromosomal microarray tests. CONCLUSION: The complication rate of AC performed after 24 weeks was 4.8%, which is significantly higher than that of second trimester AC. GA and maternal age did not affect the complication rate.

Late amniocentesis with uniparental disomy testing following successful in vitro fertilization and transfer of three mosaic embryos in a pregnancy with a favorable outcome.

OBJECTIVE: We present late amniocentesis with the application of uniparental disomy (UPD) testing following successful in vitro fertilization (IVF) and transfer of three mosaic embryos in a pregnancy with a favorable outcome. CASE REPORT: A 41-year-old, gravida 2, para 0, woman underwent late amniocentesis at 28 weeks of gestation because of advanced maternal age. The pregnancy was conceived by IVF and transfer of three mosaic embryos, i.e., one embryo with mosaic trisomies 20 and 2, one embryo with mosaic partial trisomies 9 and 3 and one embryo with partial trisomies 11 and 17. First-trimester non-invasive prenatal testing (NIPT) and fetal ultrasound revealed no abnormal findings. Late amniocentesis revealed a karyotype of 46,XY. Array comparative genomic hybridization (aCGH) revealed the result of arr [GRCh37] (X,Y) × 1, (1-22) × 2. Polymorphic DNA marker analysis using the DNAs extracted from the uncultured amniocytes and parental bloods excluded UPD 20. At 38 weeks of gestation, a healthy 3010-g male baby was delivered with no phenotypic abnormalities. CONCLUSION: Prenatal diagnosis of normal karyotype following mosaic embryo transfer should include UPD testing if necessary.

Procedure-to-delivery interval after late amniocentesis and the need for routine antenatal corticosteroids.

OBJECTIVES: The aim of this study is to assess the procedure-to-delivery interval (PDI), the obstetric complications, and the early neonatal outcome in patients that did or did not receive glucocorticosteroids (GCSs) before third-trimester amniocentesis (TTA). METHODS: A retrospectively analysis of 445 TTA procedures divided into two groups based on the administration (study group = 220 patients) or not (control group = 225 patients) of GCSs before TTA. The PDI was calculated for all patients. Obstetric and neonatal outcomes were compared between the groups. RESULTS: The rate of procedure-associated complications was similar between the groups. The mean PDI was 47.2 ± 16.8 days. The overall incidence of preterm birth was 11.7%; 9% delivered between 34 and 37 weeks and 2.7% between 28 and 34 weeks. Only nine patients (2%) delivered within seven days following TTA. The incidence of respiratory distress syndrome in the study and control groups was 1.8% and 1.3%, p = .71, respectively. There were no significant differences in other neonatal outcomes in term and preterm deliveries between the study and control groups. CONCLUSIONS: In the present study, the administration of glucocorticoids prior to TTA did not reduce the rates of neonatal complications, which was similar in both groups and not higher than the general population.