Amniocentesis in the third trimester of pregnancy

DNA concentrations in amniotic fluid according to gestational age and fetal sex: data from 2573 samples

PURPOSE

In some cases of prenatal genetic testing, an ample amount of fetal DNA is needed, to allow for parallel testing (conducting several genetic tests simultaneously). This study investigated the association between amniotic fluid DNA concentration and various factors. We aimed to define the required amount of amniotic fluid to be extracted in amniocentesis, to allow parallel testing throughout gestational weeks.

METHODS

DNA concentration was analyzed from amniocentesis samples taken during the years 2016-2022. Sex association was also analyzed in postnatal whole blood samples from a separate cohort. Theoretical minimum volume of amniotic fluid needed to ensure enough DNA for chromosomal microarray analysis and exome sequencing was calculated.

RESULTS

We focused our analysis on 2573 samples, which were taken during weeks 17-23 and 30-35. DNA concentrations increased from weeks 17 to 21, with relatively stable concentrations thereafter. Significantly higher DNA concentrations were seen in pregnancies of female fetuses. DNA concentrations in postnatal whole blood samples did not show this association. Across most weeks, the volume needed to extract 2 µg of DNA from 95% of the samples was about 34 ml.

CONCLUSION

DNA concentrations in amniotic fluid vary according to gestational age and are higher in pregnancies of female fetuses. This should be considered when determining the volume of fluid extracted and the timing of amniocentesis, with greater volumes needed in earlier stages of pregnancy.

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.

Late amniocentesis: better late than never? A single referral centre experience

INTRODUCTION

Several congenital abnormalities present late in pregnancy necessitating invasive testing to rule out genetic/infectious causes at late gestation. Not many studies have described the indications/safety of a late gestation amniocentesis.

METHODS

All records of amniocentesis performed beyond 24 weeks were reviewed and evaluated for indications, positive yield and complications.

RESULTS

About 187 women had an amniocentesis after 24 weeks for various indications with CNS abnormalities being the commonest. The total yield of positive findings was 14.60% (22/150; excluding 2 VOUS). CNS, multiple system involvement and skeletal system anormalities yielded maximum results. About 32.05% abnormalities could have potentially been detected at the time of a routine anomaly scan. Amongst all the deliveries, 2.1%  delivered spontaneously within a week of the procedure and about 5.4% delivered spontaneously within a month of the procedure.

CONCLUSION

The study emphasises the need for additional accreditation (FMF, ISUOG) of sonographers to ensure the detection of anomalies at the routine 18-20 weeks scan. Inspite of a normal mid-trimester scan, central nervous system and gastrointestinal abnormalities presented more commonly after 24 weeks. The high positive yield in our study highlights the importance of testing even in late pregnancy beyond the legal age of termination. The test could clearly stratify the pregnancies with a poor outcome whilst reassuring the others. The procedure itself did not lead to a neonatal death due to prematurity.

Incidence, clinical features and perinatal outcome in anomalous fetuses with late-onset growth restriction: cohort study

OBJECTIVE

To describe the incidence, clinical features and perinatal outcome of late-onset fetal growth restriction (FGR) associated with genetic syndrome or aneuploidy, structural malformation or congenital infection.

METHODS

This was a retrospective multicenter cohort study of patients who attended one of four tertiary maternity hospitals in Italy. We included consecutive singleton pregnancies between 32 + 0 and 36 + 6 weeks' gestation with either fetal abdominal circumference (AC) or estimated fetal weight < 10^th percentile for gestational age or a reduction in AC of > 50 percentiles from the measurement at an ultrasound scan performed between 18 and 32 weeks. The study group consisted of pregnancies with late-onset FGR and a genetic syndrome or aneuploidy, structural malformation or congenital infection (anomalous late-onset FGR). The presence of congenital anomalies was ascertained postnatally in neonates with abnormal findings on antenatal investigation or detected after birth. The control group consisted of pregnancies with structurally and genetically normal fetuses with late-onset FGR. Composite adverse perinatal outcome was defined as the presence of at least one of stillbirth, 5-min Apgar score < 7, admission to the neonatal intensive care unit (NICU), need for respiratory support at birth, neonatal jaundice and neonatal hypoglycemia. The primary aims of the study were to assess the incidence and clinical features of anomalous late-onset FGR, and to compare the perinatal outcome of such cases with that of fetuses with non-anomalous late-onset FGR.

RESULTS

Overall, 1246 pregnancies complicated by late-onset FGR were included in the study, of which 120 (9.6%) were allocated to the anomalous late-onset FGR group. Of these, 11 (9.2%) had a genetic syndrome or aneuploidy, 105 (87.5%) had an isolated structural malformation, and four (3.3%) had a congenital infection. The most frequent structural defects associated with late-onset anomalous FGR were genitourinary malformations (28/105 (26.7%)) and limb malformation (21/105 (20.0%)). Compared with the non-anomalous late-onset FGR group, fetuses with anomalous late-onset FGR had an increased incidence of composite adverse perinatal outcome (35.9% vs 58.3%; P < 0.01). Newborns with anomalous, compared to those with non-anomalous, late-onset FGR showed a higher frequency of need for respiratory support at birth (25.8% vs 9.0%; P < 0.01), intubation (10.0% vs 1.1%; P < 0.01), NICU admission (43.3% vs 22.6%; P < 0.01) and longer hospital stay (median, 24 days (range, 4-250 days) vs 11 days (range, 2-59 days); P < 0.01).

CONCLUSIONS

Most pregnancies complicated by anomalous late-onset FGR have structural malformations rather than genetic abnormality or infection. Fetuses with anomalous late-onset FGR have an increased incidence of complications at birth and NICU admission and a longer hospital stay compared with fetuses with isolated late-onset FGR. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

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.

Intra-amniotic digoxin for feticide between 21 and 30 weeks of gestation: a prospective study

OBJECTIVE

Intra-amniotic injection of digoxin is a well-known method for feticide before inducing a termination of pregnancy (TOP) at 17-24 weeks of gestation. Information on its effectiveness when administered after 24 weeks of gestation is limited. This study evaluated the efficacy of intra-amniotic digoxin injection for inducing fetal demise within 18-24 hours, at 21-30 weeks of gestation, and its safety.

DESIGN

Prospective cohort study.

SETTING

Tertiary university medical centre.

POPULATION

Women at 21-30 weeks of gestation with a singleton pregnancy, admitted for TOP.

METHODS

Intra-amniotic injection of 2 mg of digoxin was performed 1 day before medical TOP. Fetal heart activity was evaluated by ultrasound for 18-24 hours after the injection. Serum digoxin level and maternal electrocardiogram (ECG) were evaluated 6, 10, and 20 hours after injection.

MAIN OUTCOME MEASURE

Frequency of successful fetal demise.

RESULTS

Fifty-nine women participated in the study. The mean gestational age was 24⁺²  weeks (range 21⁺⁰ -30⁺⁰ ), with 29 (49.2%) beyond 24⁺⁰  weeks of gestation. Fetal cardiac activity arrest was achieved in 55/59 cases (93.2%). Normal maternal ECG recordings were noted in all cases. Mean serum digoxin levels 6 and 10 hours after injection were in the therapeutic range (1.3 ± 0.7 ng/l and 1.24 ± 0.49 ng/l, respectively) and below the toxic level (2 ng/l). Extramural delivery following digoxin did not occur. There were no cases of chorioamnionitis.

CONCLUSION

Intra-amniotic digoxin for feticide at 21-30 weeks of gestation in a singleton pregnancy appears effective and safe before TOP at advanced gestational ages.

TWEETABLE ABSTRACT

This study shows that feticide by intra-amniotic digoxin injection at 21-30 weeks of gestation appears effective and safe.

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.

Proportion of parents agreeing to delay fetal karyotyping until the third trimester of pregnancy in cases with an indication

OBJECTIVE

To assess the extent to which couples who could benefit from fetal karyotyping during the first or second trimester would agree to delay the examination until the third trimester.

METHODS

In this prospective monocentric study, the same physician suggested to some couples to delay fetal karyotyping until the third trimester.

RESULTS

458 couples participated in this study. 230 couples (230/458 = 50.2%) refused to delay the examination until the third trimester of pregnancy (group 1). For these patients, four chromosomal abnormalities led to the termination of pregnancy. Fifty-six couples (56/458 = 12.2%) who initially agreed to delay the fetal karyotyping later changed their minds (group 2). 104 couples (104/458 = 22.7%) agreed to delay the examination (group 3). For these patients, one trisomy 21 was diagnosed and led to the subsequent termination of the pregnancy at 33 weeks of amenorrhea. Sixty-eight couples (68/458 = 14.8%) refused any form of invasive prenatal diagnosis (group 4). There was no difference in the rate of preterm premature rupture of membranes, pregnancy term, premature birth rate and birth weight between the four groups.

CONCLUSIONS

Our study reports that about a quarter of couples did indeed agree to delay fetal karyotype assessment until the third trimester of pregnancy.

Determination of foetal sex in pregnancies at risk of haemophilia: a qualitative study exploring the clinical practices and attitudes of health professionals in the United Kingdom

In pregnancies at risk of haemophilia, foetal sex determination is used to plan perinatal management and to guide the offer of invasive testing in pregnancies with a male foetus. Traditionally ultrasound from 12 weeks gestation has been used, but recently options for early foetal sex determination have increased following the introduction of non-invasive prenatal diagnosis (NIPD) using cell free foetal DNA in maternal plasma. This study was conducted to identify clinical practices and examine health professional attitudes regarding NIPD for foetal sex determination. A qualitative approach using one-to-one semi structured interviews was used to enable an in-depth exploration of current practice, introduction and use of NIPD and benefits and disadvantages of offering NIPD. Interviews were conducted with consultant haematologists (N = 7), specialist haemophilia nurses (N = 7), genetic counsellors (N = 6), consultants in clinical genetics (N = 5), specialist midwives (N = 2) and obstetricians (N = 5) from 24 services across the United Kingdom (UK). Key differences in how NIPD for foetal sexing is utilized throughout the UK were identified. Some services routinely offered NIPD to all carriers of haemophilia or to all carriers of severe haemophilia, others discussed the value of NIPD with all or primarily offered NIPD as a first step to invasive testing. This study informs our understanding of how NIPD is being utilized and provides unique insights into current practice. The identification of variation between services in how prenatal testing options are offered has implications for future policy and guidelines for prenatal care.

Pregnancy outcome after third trimester amniocentesis: a single center experience

OBJECTIVE

To evaluate pregnancy outcome following late amniocentesis (>24 weeks of gestation).

STUDY DESIGN

A retrospective cohort of all women with singleton pregnancy that underwent late amniocentesis in one tertiary center.

RESULTS

Pregnancy outcome was validated in 168 women who underwent late amniocentesis. Overall, for the all study group the mean gestational age for amniocentesis was 31.6 ± 2.3 weeks and the mean gestational age at delivery was 38.1 ± 2. Indications for late amniocentesis included abnormal ultrasonographic findings (n = 120), suspected intrauterine infection (n = 23), advanced maternal age (n = 13), abnormal first or second trimester biochemical markers (n = 8) and others. The overall rate of spontaneous preterm delivery (<37 weeks) was 8% (13/168) with mean gestational age at delivery of 34.7 ± 1.3. In only five cases (3%), delivery occurred ≤ 34 weeks of gestation. In one case (0.60%) of amniocentesis performed at 32 weeks of gestation, delivery occurred within 48 hours and in other four cases (2.40%) delivery occurred within 10 days. When amniocentesis was performed due to ultrasonographic findings to rule out chromosomal abnormalities (n = 117/182), abnormal karyotype was found only in three cases.

CONCLUSIONS

The risk of significant prematurity following late amniocentesis is low. This information is important when counseling patients considering performing one.

Noninvasive prenatal diagnosis of hemophilia by microfluidics digital PCR analysis of maternal plasma DNA

Hemophilia is a bleeding disorder with X-linked inheritance. Current prenatal diagnostic methods for hemophilia are invasive and pose a risk to the fetus. Cell-free fetal DNA analysis in maternal plasma provides a noninvasive mean of assessing fetal sex in such pregnancies. However, the disease status of male fetuses remains unknown if mutation-specific confirmatory analysis is not performed. Here we have developed a noninvasive test to diagnose whether the fetus has inherited a causative mutation for hemophilia from its mother. The strategy is based on a relative mutation dosage approach, which we have previously established for determining the mutational status of fetuses for autosomal disease mutations. In this study, the relative mutation dosage method is used to deduce whether a fetus has inherited a hemophilia mutation on chromosome X by detecting whether the concentration of the mutant or wild-type allele is overrepresented in the plasma of heterozygous women carrying male fetuses. We correctly detected fetal genotypes for hemophilia mutations in all of the 12 studied maternal plasma samples obtained from at-risk pregnancies from as early as the 11th week of gestation. This development would make the decision to undertake prenatal testing less traumatic and safer for at-risk families.