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PubMedDate not supplied

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

The present study provides detailed neonatal and congenital malformation follow-up from 695 women enrolled in a prospective randomized multicenter study comparing the safety and accuracy of early (11-12 weeks of gestation) and midtrimester amniocentesis (15-16 weeks of gestation). No differences were found for total pregnancy loss (difference 0.4%; CI -3.6 to 4.4%), obstetrical or neonatal outcome. The incidence of congenital anomalies was 2.4 and 2.6% for the early amniocentesis and midtrimester amniocentesis groups, respectively. Respiratory problems were present in 2.1 and 1.6%, respectively. Musculoskeletal problems were present in 0.9 and 2.4%, respectively. It must be emphasized that before early amniocentesis can be considered as an alternative to midtrimester amniocentesis or chorionic villus sampling, careful evaluation of any fetal effects must be considered and further large randomized trials are necessary.

Amniocentesis↗

PubMedDate not supplied

The early amniocentesis study: a randomized clinical trial of early amniocentesis versus midtrimester amniocentesis.

OBJECTIVES: The primary purpose of this pilot study was to determine whether the safety of early amniocentesis (EA; 11 weeks to 12 weeks and 6 days) is similar to midtrimester amniocentesis (MA; 15 weeks to 16 weeks and 6 days). The secondary objectives were to determine the cytogenetic success and accuracy of EA compared with MA. METHODS: This prospective, randomized clinical trial compared continuous ultrasound-guided EA and MA (22-gauge needle) in patients at a late maternal age (> or = 35 years). The procedures were compared for safety, success and accuracy. RESULTS: Among the 683 women randomized and followed to pregnancy completion, there was a total of 27/344 (7.8%) and 25/339 (7.4%) fetal losses (spontaneous and induced abortions) in the EA and MA groups, respectively (difference 0.4%; CI -3.6 to 4.4%). The rate of postprocedure spontaneous fetal loss was 2.4% (8/330) in the EA group and 3.3% (10/299) in the MA group (NS). The procedure success rate at the first attempt was 97.6% in the EA group and 99.7% in the MA group. There were no diagnostic errors, and all but 2 EA cultures were successful (both repeated successfully). The perinatal outcome was similar in both groups. CONCLUSIONS: EA appears to be as safe and accurate as MA. A large multicentered, randomized trial is currently underway to verify these results.

Amniocentesis↗

PubMed1998

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.

Adult↗

PubMed1994

Comparison of first-trimester transvaginal amniocentesis with chorionic villus sampling and mid-trimester amniocentesis.

Between August 1989 and December 1991, 356 patients underwent first-trimester transvaginal amniocentesis (10-12 weeks). The same number of patients referred in the same period for mid-trimester amniocentesis (14-21 weeks) was matched also for maternal age and indication. A third group consisted of the first 356 cases in which chorionic villus sampling (CVS) was attempted. The overall success rate was 99.7 and 100 per cent for early and mid-trimester amniocentesis, respectively, and 97.2 per cent for CVS. The mean harvesting time was 12.8, 11, and 7.9 days, respectively. The percentage of patients rescheduled was 3.4 per cent in first-trimester amniocentesis, 1.7 per cent in mid-trimester amniocentesis, and 6.2 per cent in the CVS group. The early (less than 2 weeks) pregnancy loss was 1.7 and 0.6 per cent in early and mid-trimester amniocentesis, respectively, and 1.7 per cent in CVS. The total pregnancy loss was 3.2, 0.9, and 2.9 per cent, respectively. The rate of preterm birth was 6.0, 5.2 and 6.9 per cent, respectively. The results indicate that CVS has the shortest procedure-result interval, but the highest rescheduling rate. First-trimester amniocentesis has a higher procedure and laboratory success rate but, until otherwise proved, mid-trimester amniocentesis is the most efficient and safest procedure.

Abortion, Spontaneous↗

PubMedDate not supplied

On the complication risk of early amniocentesis versus standard amniocentesis.

In the last 6 years early amniocentesis for the prenatal diagnosis of chromosome aberrations has been established in many centers worldwide, but knowledge about the gynecological safety of the procedure is sparse. From 1990 to 1995 at the Evangelisches Krankenhaus Oberhausen (Germany) 3,277 early amniocenteses (between weeks 11 and 14) and 1,808 standard amniocenteses were performed in low-risk indication groups (advanced maternal age and anxiety). A complete follow-up including reports of fetal outcome was obtained in 4,444 cases (87.5%). A pregnancy age-related abortion rate was determined with a slightly higher rate of abortions up to week 28 of gestation in early amniocentesis. The total abortion rate up to week 28 after the procedure for cases with complete follow-up was 2% in early amniocentesis. Compared to standard amniocentesis performed under the same clinical conditions with an abortion rate of 1.3%, there is no statistical difference between early and standard amniocentesis (p = 0.0971). Hip and foot dislocations (22 cases) and pulmonary distress syndromes (8 newborns) showed no significant correlation with the gestational week. Given the high normal background rate of spontaneous abortions in the early period of pregnancy without an invasive procedure, early amniocentesis can be considered as a safe alternative to chorionic villus sampling and standard amniocentesis.

Abortion, Induced↗

PubMed1985

Encouraging patients to undergo prenatal genetic counseling before the day of amniocentesis. Its effect on the use of amniocentesis.

The purpose of this study was to determine if encouraging in-depth prenatal genetic counseling before the day of possible genetic amniocentesis affected the use of amniocentesis. Five hundred two patients were referred to our center for prenatal genetic services during a 15-month period. All patients were scheduled for genetic counseling before possible amniocentesis. During the initial three months (group I), patients were routinely scheduled for counseling on the same day of the procedure unless they requested earlier counseling. During the subsequent 12 months (group II), patients were encouraged to undergo counseling before the day of planned amniocentesis, and 48% agreed. When early counseling was encouraged, the use of amniocentesis decreased from 85% (group I) to 73% (group II) (P less than .025). Among patients with advanced maternal age as the only indication for testing (n = 375), utilization of amniocentesis decreased from 93% (group I) to 78% (group II) (P less than .005). A policy of encouraging early prenatal genetic counseling appears to be a significant factor in the use of genetic amniocentesis.

Amniocentesis↗

PubMed1999

Technical factors in early amniocentesis predict adverse outcome. Results of the Canadian Early (EA) versus Mid-trimester (MA) Amniocentesis Trial.

The purpose of this study was to identify risk factors for fetal loss and other pregnancy complications associated with genetic amniocentesis. Data were acquired in the Canadian Early Amniocentesis Trial (CEMAT), a multicentered (12) prospective, randomized trial comparing continuous ultrasound-guided early amniocentesis (EA) and mid-trimester amniocentesis (MA) (CEMAT Group, 1998). Details of the procedure were recorded and analysed by allocation (EA versus MA), operator and centre, and correlated with pregnancy outcome. A total of 62 spontaneous pregnancy losses occurred between the procedure and 20 weeks' gestation among the 3691 patients who received their procedures within the allocated window (EA=53/1916, MA=9/1775). Technical factors correlating with these losses included procedures 'judged to be difficult' by the operator, and post-procedure amniotic fluid leakage or bleeding. Maternal risk factors included maternal hypertension (fetal loss 11. 1 per cent, compared with non-hypertensive women, 2.6 per cent) increased body mass index (BMI) and gravidity of three or greater. Allocation to EA was predictive of fetal loss, as well as failed procedure, multiple needle insertions, amniotic fluid leakage, failed culture and talipes equinovarus, in excess compared with MA. In conclusion, in this large prospective randomized trial evaluating amniocentesis, specific maternal, fetal and procedural variables were found to be predictive of fetal loss and adverse pregnancy outcome. Performing amniocentesis before 13 weeks' gestation (EA) was the major predictive factor for adverse outcome. These data suggest that first-trimester chorionic villus sampling (CVS) and MA will likely remain the invasive procedures of choice for evaluation of fetal karyotype.

Abortion, Spontaneous↗

PubMed1993

[Amniocentesis to study the fetal karyotype before 16 weeks of amenorrhea. Prospective study comparing it with conventional amniocentesis].

In a prospective study, we compared early amniocentesis (13-15 weeks of amenorrhea, n = 67) with conventional amniocentesis (16-20 weeks, n = 105). Early amniocentesis was not associated with complications and cell culture was possible in every case. Sampling failures were more frequent (4.5% vs 0.9%, p = 0.057), but had no deleterious effects and this rate can probably be reduced with experience. The mean time required for karyotyping was only slightly longer: 17.0 (SD 2.8) days vs 15.8 (SD 2.0) days (p < 0.01). These results agree with other recent studies suggesting that early amniocentesis is a simple and safe method which can be performed several weeks before conventional amniocentesis.

Adult↗

PubMed1994

Risk assessment of amniocentesis between 11 and 15 weeks: comparison to later amniocentesis controls.

We studied 693 consecutive early amniocenteses (prior to 15 weeks) and found a spontaneous abortion rate to 28 weeks' gestation of 1.5 per cent. A control group of women having standard amniocentesis (15-20 weeks) experienced a 0.6 per cent fetal loss in the same period. There were no other apparent differences between the two groups. Early amniocentesis results are generally available 4-6 weeks before standard amniocentesis and 1-3 weeks after chorionic villus sampling (CVS). Alpha-fetoprotein (AFP) can be accurately assayed in 11- to 15-week amniotic fluid samples but additional studies are necessary to determine the accuracy of neural tube defect (NTD) detection. Including the present study, over 5800 early amniocenteses have been reported and the results suggest that this is a relatively safe prenatal diagnostic test and an alternative to CVS and later amniocentesis.

Abortion, Spontaneous↗

PubMed1989

Multicentre randomised clinical trial of chorion villus sampling and amniocentesis. First report. Canadian Collaborative CVS-Amniocentesis Clinical Trial Group.

2787 women who were aged 35 years or more at expected date of delivery were randomised to chorionic villus sampling (CVS) at 9-12 weeks gestation or amniocentesis at 15-17 weeks for the detection of a chromosomal abnormality in the fetus. 396 women were excluded after randomisation because of a non-viable fetus, a multiple pregnancy, or infection or because the pregnancy was too far advanced (more than 12 completed weeks). Among all women eligible at the time of the first study procedure there were 89/1169 (7.6%, 95% confidence interval [CI] 6.2-9.3%) total losses (spontaneous and induced abortions and late losses) in the CVS group and 82/1174 (7.0%, CI 5.6-8.6%) in the amniocentesis group for an excess of 0.6% for those women undergoing CVS, with a tendency to later losses in the CVS group. Approximate 95% CIs indicate that this difference is most unlikely to be greater than 2.7%. Mean birthweights for each week of gestation were similar in both groups, with no evidence of excess small-for-gestational age babies in the CVS group. The proportion of preterm births were similar in both groups. Perinatal mortality was greater in the CVS group, the greatest imbalance being beyond 28 weeks. Preliminary analysis has not disclosed an obvious recurrent event in the CVS group which might explain a cause-and-effect relationship for these late fetal losses. There is no evidence of any excess intrauterine growth retardation babies in the CVS group. Maternal morbidity was similar in both groups. 103/1037 (9.9%) women eligible for CVS had a further amniocentesis; 32 of these second procedures were needed to complete the cytogenetic diagnosis. More problems such as confined mosaicism and maternal cell contamination occurred in the interpretation of the CVS samples, but these were clarified by amniocentesis when appropriate.

Abortion, Induced↗

PubMed1992

Canadian multicenter randomized clinical trial of chorion villus sampling and amniocentesis. chromosome mosaicism in CVS and amniocentesis samples.

Data on 1040 chorionic villus and 969 amniotic fluid samples were collected from women studied in the Canadian Multicentre Randomized Clinical Trial of Chorion Villus Sampling and Amniocentesis. Cytogenetic results were obtained from 98.0 per cent of chorionic villus samples and from 99.9 per cent of amniotic fluid samples. Level I mosaicism (a single cell with an abnormal karyotype) occurred frequently in both chorionic villus and amniotic fluid samples and appeared to have no clinical significance. Level II mosaicism occurred in 0.9 per cent of CVS mesenchyme and 1.5 per cent of amniotic fluid cultures and in general was not perceived to be of sufficient concern to warrant cytogenetic follow-up studies. Level III mosaicism was reported in 18 CVS cases (15 cytotrophoblast, 1 mesenchyme, and 2 with both cell methods) and in one amniotic fluid case. In all cases but one (fetus with trisomy 18), level III mosaicism was confined to the placenta. Maternal cell contamination occurring with a frequency of 6.4 per cent in the mesenchyme analyses was a concern. This study supports the final report of the Canadian Multicentre Randomized Clinical Trial of Chorion Villus Sampling and Amniocentesis. Cytogenetic analysis of chorionic villus samples appears to be an acceptable alternative to the analysis of amniotic fluid samples. However, because of mosaicism and maternal cell contamination concerns, the examination of both cytotrophoblast preparations and mesenchyme cultures from chorionic villus samples is recommended.

Adult↗

PubMed1999

Genetic amniocentesis: gestation-specific pregnancy outcome and comparison of outcome following early and traditional amniocentesis.

Amniocentesis remains the most common prenatal diagnostic invasive procedure for fetal karyotyping. During counselling prior to this procedure miscarriage rates are often quoted as a single figure. In this review of 2924 amniocenteses, we report that miscarriage rates vary with the gestational age at which the procedure is performed. The total miscarriage rate was 1.0 per cent after early amniocenteses (11 + 0-14 + 6 weeks) and 1.2 per cent after traditional mid-trimester amniocenteses (15 + 0-18 + 6 weeks). The rate was greatest (3.1 per cent) for amniocenteses performed after 18 + 6 weeks' gestation. The cumulative miscarriage risk increased from 0.03 per cent one week after the procedure to plateau at 1.1 per cent five weeks after the procedure. The preterm and still-birth rates following amniocenteses were similar in early and traditional mid-trimester amniocenteses but were significantly higher when amniocenteses were performed after 19 weeks' gestation. Although the incidence of talipes equinovarus was higher after early amniocentesis compared with traditional mid-trimester amniocenteses (1.4 per cent versus 0.2 per cent), none of the affected infants required corrective surgery. We conclude that counselling for this procedure should be tailored to each unit's unintended fetal loss rate based on cumulative rates. Such figures should be available to parents to assist them in their decision-making.

Adult↗

PubMed1999

Club foot, an adverse outcome of early amniocentesis: disruption or deformation? CEMAT. Canadian Early and Mid-Trimester Amniocentesis Trial.

An association between the occurrence of club foot and early amniocentesis has been reported. The largest of these randomised studies was the Canadian Early and Mid-Trimester Amniocentesis Trial. Data describing the neonatal outcome, focusing on this association, are presented. Possible mechanisms for the association and the implications for the development of club foot are discussed.

Adult↗

PubMed1978

Experience with amniocentesis at the Johannesburg Amniocentesis Clinic in 1976.

One hundred and seventy-six amniocenteses were performed in the Johannesburg Amniocentesis Clinic in 1976. These were for genetic studies, assessment of fetal lung maturity and assessment of the severity of rhesus disease. The indications for amniocentesis and the results are discussed. The overall complication rate was low. This was due to certain precautions and approaches taken, which are detailed.

Adult↗

PubMed1978