Ultrasound screening of chromosomal abnormalities by nuchal translucency

2006 ◽  
pp. 930-938
2007 ◽  
Vol 135 (3-4) ◽  
pp. 153-156 ◽  
Author(s):  
Aleksandra Trninic-Pjevic ◽  
Aleksandra Novakov-Mikic

Introduction: A retrocervical subcutaneous collection of fluid at 11-14 weeks of gestation, can be visualized by ultrasound as nuchal translucency (NT). Objective. To examine the distribution of fetal nuchal translucency in low risk population, to determine the detection rate of chromosomal abnormalities in the population of interest based on maternal age and NT measurement. Method. Screening for chromosomal defects, advocated by The Fetal Medicine Foundation (FMF), was performed in 1,341 pregnancies in the period January 2000 - April 2004. Initial risk for chromosomal defects (based on maternal and gestational age) and corrected risk, after the NT measurement, were calculated. Complete data were collected from 1,048 patients. Results. Out of 1,048 pregnancies followed, 8 cases of Down?s syndrome were observed, 7 were detected antenatally and 6 out of 7 were detected due to screening that combines maternal age and NT measurement. According to our results, sensitivity of the screening for aneuploidies based on maternal age alone was 12.5% and false positive rate 13.1%, showing that screening based on NT measurement is of great importance. Screening by a combination of maternal age and NT, and selecting a screening-positive group for invasive testing enabled detection of 75% of fetuses with trisomy 21. Conclusion. In screening for chromosomal abnormalities, an approach which combines maternal age and NT is effective and increases the detection rate compared to the use of any single test. .


2007 ◽  
Vol 60 (1-2) ◽  
pp. 66-70 ◽  
Author(s):  
Aleksandra Novakov-Mikic ◽  
Zoran Potic ◽  
Aleksandra Pjevic

Introduction Screening for chromosomal abnormalities identifies the group of women at higher risk for having a fetus with chromosomal abnormalities and the need for fetal karyotyping. In order to provide high quality screening, strict criteria for certification of operators are introduced, issued by the Fetal Medicine Foundation (FMF), which enables annual external control of results. The aim of this study was to review the results of five-year prenatal screening for chromosomal abnormalities in Novi Sad, Serbia. Material and methods Ultrasound screening at 11-15 weeks gestation was performed, assessing fetal morphology, crowner-rump length and nuchal translucency (NT) according to the FMF guidelines. Risk for chromosomal abnormalities included the initial risk, based on maternal age, gestational age and anamnestic data, and corrected risk, which took into account the initial risk and the value of the nuchal translucency. The corrected risk was issued by the computer program issued by the FMF. Results During the period 1999 - 2004, 4580 pregnant women were scanned. The risk for chromosomal abnormality was calculated using the FMF program in 2245 cases and the outcome was known in 1406 cases. The majority of women were between 25 and 29 years of age (37%), and 12% were older than 35 years. NT was below the median in 43% of cases and above in 57%, 3.7% of cases were above the 95th centile. 89% of women were younger than 35, and the risk was reduced in 97% of cases. There were three false negative cases. In 3% of women from this group the risk was increased, out of which there were five cases of trisomy 21 and two terminations were done due to major anomalies. In the group of women over 35 years, the risk was reduced in 95% of cases and in all of them but two the karyotype was normal. In one of the two cases there was a large omphalocele and the karyotype was trisomy 18, and in the other fetus appeared normal, but after amniocentesis due to maternal anxiety, karyotype was 47, XYY. In 5% of women at higher risk there was one trisomy 21, bilateral multicystic kidneys were found in one case as well as one hydrocephalus. Conclusion Combined screening by maternal age and nuchal translucency is superior to screening by maternal age only - (sensitivity 66% vs 20%, false postive results 3% vs 15%, area under ROC 0.90 vs 0.69).


Author(s):  
N.P. Veropotvelyan, A.A. Bondarenko

Objective. To evaluate the pre- and postnatal outcomes of euploid fetuses with aplasia/hypoplasia of the nasal bones (NB). Methods. We have made the catamnestic monitoring of children with a normal karyotype, who had been prenatally detected NB aplasia or hypoplasia (less than 5 perentile) at 11–24 weeks of gestation at ultrasound screening in the period between 2006–2015 years. Our study included a selection of 242 fetuses with NB aplasia or hypoplasia, in 128 (52.8 %) of them the NB was not visualized or appeared as an echogenic dot only. Results. Among all 63 fetuses with NB aplasia (absence or looks as an echogenic dot) in the 1st trimester in 24 (38 %) cases chromosomal abnormalities (CA) were found (including T21 — 15 (62.5 %) cases). Other 39 (61.9 %) fetuses had a normal karyotype. Among 65 fetuses with NB aplasia, examined in the 2nd trimester of gestation 12 (18.4 %) cases of CA were detected (one fetus with T21 had the only one ultrasound marker – isolated NB aplasia), 53 (81.5 %) fetuses had a normal karyotype. 62 mothers of the euploid fetuses with NB aplasia had been surveyed. We have received and analyzed 31 (50 %) responses. In 16 cases of euploid fetuses with NB, aplasia pregnancy outcome was adverse or relatively unfavorable, only 5 (31.2 %) fetuses of them had isolated NB aplasia. In other cases healthy full-term infants were born, who showed normal height and weight indexes, physical and psychomotor development observed in age from 0 to 10. Conclusion. In 51.6 % fetuses and children prenatally had aplasia of the nasal bone was marked by unfavorable pre- or postnatal outcome, according to the survey of their mothers.


2001 ◽  
Vol 119 (1) ◽  
pp. 19-23 ◽  
Author(s):  
Gregório Lorenzo Acácio ◽  
Ricardo Barini ◽  
Walter Pinto Júnior ◽  
Renato Luís Silveira Ximenes ◽  
Heverton Pettersen ◽  
...  

CONTEXT: The literature shows an association between several ultrasound markers and chromosome abnormality. Among these, measurement of nuchal translucency has been indicated as a screening method for aneuploidy. The trisomy of chromosome 21 has been most evaluated. OBJECTIVE: To define the best fixed cutoff point for nuchal translucency, with the assistance of the ROC curve, and its accuracy in screening all fetal aneuploidy and trisomy 21 in a South American population. TYPE OF STUDY: Validation of a diagnostic test. SETTING: This study was carried out at the State University of Campinas, Campinas, Brazil. PARTICIPANTS: 230 patients examined by ultrasound at two tertiary-level private centers, at 10 to 14 weeks of gestation. DIAGNOSTIC TEST: The participants consisted of all those patients who had undergone ultrasound imaging at 10 to 14 weeks of gestation to measure nuchal translucency and who had had the fetal or neonatal karyotype identified. MAIN MEASUREMENTS: Maternal age, gestational age, nuchal translucency measurement, fetal or neonatal karyotype. RESULTS: Prevalence of chromosomal defects -- 10%; mean age -- 35.8 years; mean gestational age -- 12 weeks and 2 days; nuchal translucency (NT) thickness -- 2.18 mm. The best balance between sensitivity and specificity were values that were equal to or higher than 2.5 mm for overall chromosomal abnormalities as well as for the isolated trisomy 21. The sensitivity for overall chromosomal abnormalities and trisomy 21 were 69.5% and 75%, respectively, and the positive likelihood ratios were 5.5 and 5.0, respectively. CONCLUSION: The measurement of nuchal translucency was found to be fairly accurate as an ultrasound marker for fetal abnormalities and measurements equal to or higher than 2.5 mm were the best fixed cutoff points.


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