The early amniocentesis study: a randomized clinical trial of early amniocentesis and midtrimester amniocentesis. II. Evaluation of procedure details and neonatal congenital anomalies

Invasive Prenatal Diagnostic Testing for Aneuploidies in Singleton Pregnancies: A Comparative Review of Major Guidelines

Sophisticated screening protocols for genetic abnormalities constitute an important component of current prenatal care, aiming to identify high-risk pregnancies and offer appropriate counseling to parents regarding their options. Definite prenatal diagnosis is only possible by invasive prenatal diagnostic testing (IPDT), mainly including amniocentesis and chorionic villous sampling (CVS). The aim of this comparative review was to summarize and compare the existing recommendations on IPDT from the most influential guidelines. All the reviewed guidelines highlight that IPDT is indicated based on a positive screening test rather than maternal age alone. Other indications arise from medical history and sonography, with significant variations identified between the guidelines. The earlier time for amniocentesis is unequivocally set at ≥15 gestational weeks, whereas for CVS, the earlier limit varies from ≥10 to ≥11 weeks. Certain technical aspects and the overall approach demonstrate significant differences. Periprocedural management regarding Rhesus alloimmunization, virologic status and use of anesthesia or antibiotics are either inconsistent or insufficiently addressed. The synthesis of an evidence-based algorithm for IPDT is of crucial importance to healthcare professionals implicated in prenatal care to avoid unnecessary interventions without compromising optimal prenatal care.

Difference in Procedure-Related Risk of Miscarriage between Early and Mid-Trimester Amniocentesis: A Retrospective Cohort Study

Early amniocentesis (EA)—before 15 gestational weeks—is not recommended because of a high rate of miscarriages. Most studies performed amniocentesis at very early stages of pregnancy (11–13 weeks of gestational age). However, amniocentesis performed at 14 gestational weeks could be an important alternative to mid-trimester amniocentesis (MA) because it shortens the time period between the screening (non-invasive prenatal test (NIPT)) and the diagnostic test (amniocentesis). This study aimed to compare the procedure-related risk of miscarriage between MA (15 + 0 to 17 + 6 weeks of gestational age) and EA (14 + 0–6 weeks of gestational age). This is a multicentric, retrospective cohort study from 1 January 2007 to 21 November 2018, comparing the MA to the EA cohort. Procedure-related fetal loss is defined as spontaneous abortion occurring within 4 weeks of the procedure. Multiple gestations, amniocenteses performed after 17 or before 14 weeks, indications other than prenatal genetic diagnoses and procedures performed by less experienced gynaecologists were excluded. Complete outcome data were available for 1107 out of 1515 women (73.1%): 809 (69.9%) in the MA and 298 (83.2%) in the EA cohort. No significant difference was found (EA 0.82% vs. MA 0.36%; p = 0.646). The difference was 0.46% (odds ratio = 0.673; 95% confidence interval = 0.123–3.699). This study found no significant difference in the procedure-related risk of miscarriage when EA was compared to MA. EA might be considered a safe alternative, though further research is necessary.

5-Year review on amniocentesis and its maternal fetal complications

Background Amniocentesis is a well-known invasive procedure which is commonly carried out in the second trimester. The indication for amniocentesis varies throughout countries and centers. Despite providing significant prenatal diagnosis; many maternal and fetal complications have been reported from previous studies. Materials and methods This retrospective study aimed to determine the maternal and fetal complications following amniocentesis. This study involved all patients who underwent amniocentesis from January 2012 until June 2017 in a tertiary centre. Maternal age, parity, premorbid medical conditions, amniocentesis indications, gestational age during amniocentesis, karyotyping results, complications during and post procedure and the fetal outcomes were reviewed and analyzed. Results One hundred and fourteen patients' medical records were reviewed and the majority of patients (50.9%) ranged in age from age 30 to 39 years old with mean age of 34.29 years. Amniocentesis was performed during the second trimester in the majority of patients (71.1%). The indications for amniocentesis in this study were polyhydramnios (7.9%), advanced maternal age (9.6%), risk of Down's syndrome (31.6%), increased risk of Patau syndrome (6.1%), increased risk of Edward's syndrome (4.4%) and abnormal fetal ultrasonography (70.2%). Cytogenetics results of amniocentesis were normal in 82 patients (71.9%). The majority of patients (86.0%) had no complications. Two patients (12.5%) had intrauterine death presumed to be procedural related. Conclusion This 5-year retrospective study on amniocentesis procedure showed that the majority of amniocentesis were safe as 86.0% of the patients were free from any complications. Anticipating its complication is important as there is always a risk even though it is a safe procedure in general.

Amniocentesis and chorionic villus sampling for prenatal diagnosis

BACKGROUND

During pregnancy, fetal cells suitable for genetic testing can be obtained from amniotic fluid by amniocentesis (AC), placental tissue by chorionic villus sampling (CVS), or fetal blood. A major disadvantage of second trimester amniocentesis is that the results are available relatively late in pregnancy (after 16 weeks' gestation). Earlier alternatives are chorionic villus sampling (CVS) and early amniocentesis, which can be performed in the first trimester of pregnancy.

OBJECTIVES

The objective of this review was to compare the safety and accuracy of all types of AC (i.e. early and late) and CVS (e.g. transabdominal, transcervical) for prenatal diagnosis.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (3 March 2017), ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP; 3 March 2017), and reference lists of retrieved studies.

SELECTION CRITERIA

All randomised trials comparing AC and CVS by either transabdominal or transcervical route.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. The quality of the evidence was assessed using the GRADE approach.

MAIN RESULTS

We included a total of 16 randomised studies, with a total of 33,555 women, 14 of which were deemed to be at low risk of bias. The number of women included in the trials ranged from 223 to 4606.Studies were categorized into six comparisons: 1. second trimester AC versus control; 2. early versus second trimester AC; 3. CVS versus second trimester AC; 4. CVS methods; 5. Early AC versus CVS; and 6. AC with or without ultrasound.One study compared second trimester AC with no AC (control) in a low risk population (women = 4606). Background pregnancy loss was around 2%. Second trimester AC compared to no testing increased total pregnancy loss by another 1%. The confidence intervals (CI) around this excess risk were relatively large (3.2% versus 2.3 %, average risk ratio (RR) 1.41, 95% CI 0.99 to 2.00; moderate-quality evidence). In the same study, spontaneous miscarriages were also higher (2.1% versus 1.3%; average RR 1.60, 95% CI 1.02 to 2.52; high-quality evidence). The number of congenital anomalies was similar in both groups (2.0% versus 2.2%, average RR 0.93, 95% CI 0.62 to 1.39; moderate-quality evidence).One study (women = 4334) found that early amniocentesis was not a safe early alternative compared to second trimester amniocentesis because of increased total pregnancy losses (7.6% versus 5.9%; average RR 1.29, 95% CI 1.03 to 1.61; high-quality evidence), spontaneous miscarriages (3.6% versus 2.5%, average RR 1.41, 95% CI 1.00 to 1.98; moderate-quality evidence), and a higher incidence of congential anomalies, including talipes (4.7% versus 2.7%; average RR 1.73, 95% CI 1.26 to 2.38; high-quality evidence).When pregnancy loss after CVS was compared with second trimester AC, there was a clinically significant heterogeneity in the size and direction of the effect depending on the technique used (transabdominal or transcervical), therefore, the results were not pooled. Only one study compared transabdominal CVS with second trimester AC (women = 2234). They found no clear difference between the two procedures in the total pregnancy loss (6.3% versus 7%; average RR 0.90, 95% CI 0.66 to 1.23, low-quality evidence), spontaneous miscarriages (3.0% versus 3.9%; average RR 0.77, 95% CI 0.49 to 1.21; low-quality evidence), and perinatal deaths (0.7% versus 0.6%; average RR 1.18, 95% CI 0.40 to 3.51; low-quality evidence). Transcervical CVS may carry a higher risk of pregnancy loss (14.5% versus 11.5%; average RR 1.40, 95% CI 1.09 to 1.81), but the results were quite heterogeneous.Five studies compared transabdominal and transcervical CVS (women = 7978). There were no clear differences between the two methods in pregnancy losses (average RR 1.16, 95% CI 0.81 to 1.65; very low-quality evidence), spontaneous miscarriages (average RR 1.68, 95% CI 0.79 to 3.58; very low-quality evidence), or anomalies (average RR 0.68, 95% CI 0.41 to 1.12; low-quality evidence). We downgraded the quality of the evidence to low due to heterogeneity between studies. Transcervical CVS may be more technically demanding than transabdominal CVS, with more failures to obtain sample (2.0% versus 1.1%; average RR 1.79, 95% CI 1.13 to 2.82, moderate-quality evidence).Overall, we found low-quality evidence for outcomes when early amniocentesis was compared to transabdominal CVS. Spontaneous miscarriage was the only outcome supported by moderate-quality evidence, resulting in more miscarriages after early AC compared with transabdominal CVS (2.3% versus 1.3%; average RR 1.73, 95% CI 1.15 to 2.60). There were no clear differences in pregnancy losses (average RR 1.15, 95% CI 0.86 to 1.54; low-quality evidence), or anomalies (average RR 1.14, 95% CI 0.57 to 2.30; very low-quality evidence).We found one study that examined AC with or without ultrasound, which evaluated a type of ultrasound-assisted procedure that is now considered obsolete.

AUTHORS' CONCLUSIONS

Second trimester amniocentesis increased the risk of pregnancy loss, but it was not possible to quantify this increase precisely from only one study, carried out more than 30 years ago.Early amniocentesis was not as safe as second trimester amniocentesis, illustrated by increased pregnancy loss and congenital anomalies (talipes). Transcervical chorionic villus sampling compared with second trimester amniocentesis may be associated with a higher risk of pregnancy loss, but results were quite heterogeneous.Diagnostic accuracy of different methods could not be assessed adequately because of incomplete karyotype data in most studies.

Antibiotic prophylaxis before second-trimester genetic amniocentesis (APGA): a single-centre open randomised controlled trial

OBJECTIVE

To compare procedure-related pregnancy loss after second-trimester genetic amniocentesis in women given an antibiotic prophylaxis and controls.

METHODS

Prospective, open randomised controlled single-centre study between January 1999 and December 2005 at Artemisia Fetal Maternal Medical Centre. A follow-up within 4 weeks after the procedure was done.Of 36,347 eligible women, 1424 refused to participate and 34,923 were enrolled and randomised with unequal chance of selection, 21,991 were assigned to treatment group and 12,932 were assigned to the control group, and did not receive any placebo. Oral azithromycin, 500 mg per day, was administered 3 days before amniocentesis. The primary endpoint was the procedure-related pregnancy loss. The secondary endpoint was the rate of preterm premature rupture of membranes.

RESULTS

The rate of abortion related to the amniocentesis was 7/21 219 women (0.03%, 95% CI 0.009-0.057) in the intervention group, and 36/12 529 (0.28%, 0.28-0.30) in controls (p = 0.0019). The rate of preterm premature rupture of membranes was 14/21 219 (0.06%, 0.031-0.101) in the intervention group, and 140/12 529 (1.12%, 0.94-1.30) in the control group (p = 0.001).

CONCLUSIONS

Antibiotic prophylaxis before second-trimester amniocentesis reduced the risk of abortion and of rupture of the membranes.

Procedure-Related Complications of Amniocentesis and Chorionic Villous Sampling

OBJECTIVE

To compile a systematic review of complications related to genetic amniocentesis and chorionic villus sampling (CVS) to provide benchmark data for counseling and performance assessment of individual operators.

DATA SOURCES

We searched the MEDLINE database for articles published after January 1, 1995, that reported data for at least 100 women with singleton pregnancies with genetic amniocentesis after 14 weeks of pregnancy and reports of CVS carried out transabdominally between 10 and 14 weeks.

METHODS OF STUDY SELECTION

For amniocentesis, 29 articles fulfilled search criteria. Sixteen studies fulfilled search criteria for CVS.

TABULATION, INTEGRATION, AND RESULTS

After genetic amniocentesis, pooled pregnancy loss within 14 days was 0.6% (95% confidence interval [CI] 0.5-0.7), rising to 0.9% (95% CI 0.6-1.3) for pregnancy loss before 24 weeks and 1.9% (95% CI 1.4-2.5) for total pregnancy loss. Corresponding figures for CVS were 0.7%, 1.3%, and 2%. The data on multiple insertions showed large heterogeneity, ranging from 0.2% to 2.9% for amniocentesis (pooled risk 2.0%, 95% CI 0.9-3.6) and from 1.4% to 26.6% for CVS (pooled risk 7.8%, 95% CI 3.1-14.2). Only five amniocentesis studies provided controls, but none was matched for gestational age. Pooled relative risks for fetal loss before 28 weeks and total pregnancy loss were 1.46 (95% CI 0.86-2.49) and 1.25 (95% CI 1.02-1.53), respectively.

CONCLUSION

Although the risks of pregnancy loss are relatively low, lack of adequate controls tends to underestimate the true added risk of prenatal invasive procedures.

Amniocentesis and chorionic villus sampling for prenatal diagnosis

BACKGROUND

A major disadvantage of second trimester amniocentesis is that the result is usually available only after 18 weeks' gestation. Chorionic villus sampling (CVS) and early amniocentesis can be done between 9 and 14 weeks and offer an earlier alternative.

OBJECTIVES

The objective was to assess comparative safety and accuracy of second trimester amniocentesis, early amniocentesis, transcervical and transabdominal CVS.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (March 2003) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2002).

SELECTION CRITERIA

All randomised trials comparing amniocentesis and CVS.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed eligibility and trial quality and performed data extraction. We analysed the data using RevMan software.

MAIN RESULTS

A total of 14 randomised studies have been included. In a low risk population with a background pregnancy loss of around 2%, a second trimester amniocentesis will increase this risk by another 1%. This difference did not reach statistical significance, but the increase in spontaneous miscarriages following second trimester amniocentesis compared with controls (no amniocentesis) did (2.1% versus 1.3%; relative risk (RR) 1.02 to 2.52). Early amniocentesis is not a safe early alternative to second trimester amniocentesis because of increased pregnancy loss (7.6% versus 5.9%; RR 1.29, 95% CI 1.03 to 1.61) and higher incidence of talipes compared to CVS (1.8% versus 0.2%; RR 6.43, 95% CI 1.68 to 24.64).Compared with second trimester amniocentesis, transcervical CVS carries a significantly higher risk of pregnancy loss (14.5% versus 11%; RR 1.40, 95% CI 1.09 to 1.81) and spontaneous miscarriage (12.9% versus 9.4%; RR 1.50, 95% CI 1.07 to 2.11). One study compared transabdominal CVS with second trimester amniocentesis and found no significant difference in the total pregnancy loss between the two procedures (6.3% versus 7%). Transcervical CVS is more technically demanding than transabdominal CVS with more failures to obtain sample and more multiple insertions.

REVIEWER'S CONCLUSIONS

Second trimester amniocentesis is safer than transcervical CVS and early amniocentesis. If earlier diagnosis is required, transabdominal CVS is preferable to early amniocentesis or transcervical CVS. In circumstances where transabdominal CVS may be technically difficult the preferred options are transcervical CVS in the first trimester or second trimester amniocentesis.

Association between congenital foot anomalies and gestational age at amniocentesis

OBJECTIVES

Our objectives were to confirm the reported association between early amniocentesis and congenital foot anomalies as well as to report, for the first time, on the outcome of amniocenteses performed during the 13th and 14th weeks of gestation.

METHODS

We conducted a triple cohort retrospective study of 4457 amniocenteses. Cohort definitions: early amniocentesis (EA), 11 weeks and 0/7 days to 12 weeks to 6/7 days; early midtrimester amniocentesis (EMA), 13 weeks and 0/7 days to 14 weeks and 6/7 days; and midtrimester amniocentesis (MA), 15 weeks and 0/7 days to 19 weeks and 6/7 days. Outcome measures were obtained by searching the Alberta Congenital Anomalies Surveillance System (ACASS) database for children born with foot anomalies represented by International Classification of Diseases version 9 (ICD-9) codes 754.5, 754.6 and 754.7.

RESULTS

Incidences of congenital foot anomalies were: EA 11/980 (1.1%), EMA 11/2515 (0.4%), and MA 1/962 (0.1%). There is a significant difference between the EA and EMA cohorts (p=0.019) and between the EA and MA cohorts (p=0.003); however, these data suggest there is no difference between EMA and MA cohorts (p=0.11).

CONCLUSIONS

Our incidence of congenital foot anomalies of 1.1% for women who underwent EA is similar to previously reported data, which further validates this association; however, our data also suggest that the foot anomaly risk may be limited to amniocenteses performed before the 13th week of gestation.

First trimester prenatal diagnosis: amniocentesis

Twenty years after midtrimester genetic amniocentesis was first used, first trimester invasive prenatal procedures were introduced. Chorionic villous sampling presents some disadvantages that entitled many centers to look into an alternative for first trimester diagnosis. Early amniocentesis (EA) can be performed effectively, as shown over the years in many observational studies and partially randomized and randomized trials. Recently, a multicenter randomized trial (Canadian Early and Midtrimester Amniocentesis Trial) reported a higher total pregnancy loss, a significant increased incidence of musculoskeletal foot deformities, a significant increased culture failure rate, and an increased postamniocentesis rate of leakage in the EA group compared with midtrimester amniocentesis. These results concerning EA procedures from 11w(+0) to 12w(+6) should be included in any pre-EA counseling. However, further trials have started to evaluate EA procedures between 13w(+0) to 14w(+6).

Randomised trial to assess safety and fetal outcome of early and midtrimester amniocentesis. The Canadian Early and Mid-trimester Amniocentesis Trial (CEMAT) Group

BACKGROUND

Most published reports on early amniocentesis are of cohort studies rather than randomised trials. This study was designed to assess the safety and cytogenetic accuracy of early amniocentesis in-contrast to midtrimester amniocentesis in a randomised multicentre setting.

METHODS

Pregnant women were randomly allocated early amniocentesis (between 11(+0) and 12(+6) gestational weeks(days)) or midtrimester (between 15(+0) and 16(+6) gestational weeks(days)) amniocentesis. A detailed fetal ultrasound examination was done between 15 and 20 gestational weeks in all women. All amniocenteses were done under continuous ultrasound guidance: 11 mL (early amniocentesis) or 20 mL (midtrimester amniocentesis) of amniotic fluid were removed for cytogenic analysis. No more than two needle insertions were done on the same day. All fetal losses (spontaneous or induced abortions) were counted as outcome events and post-procedural losses had cytogenic analysis. Maternal and fetal health were assessed at 20-22 weeks and 5 weeks after delivery. Logistic regression analysis was used to assess the significance of the differences between the early amniocentesis and midtrimester amniocentesis groups.

FINDINGS

4374 pregnant women took part in the study. 1916 (87.8%) of 2183 women in the early amniocentesis group had their amniocentesis before 13 gestational weeks. 1775 (81.2%) of 2185 women in the midtrimester group had their amniocentesis after 15 gestational weeks. There was a significant difference in total fetal losses for early amniocentesis compared with midtrimester amniocentesis (7.6% vs 5.9%; difference 1.7%, one-sided CI 2.98%, p = 0.012). There was a significant increase in talipes equinovarus in the early amniocentesis group compared with the midtrimester amniocentesis group (1.3% vs 0.1%, p = 0.0001). There was a significant difference in postprocedural amniotic-fluid leakage (early amniocentesis 3.5% vs midtrimester amniocentesis 1.7%, p = 0.0007).

INTERPRETATION

Our study shows that early amniocentesis is associated with an increased risk of fetal loss and talipes equinovarus. Our results should be taken into consideration when invasive prenatal diagnosis is being offered.