Características ecográficas y anomalías congénitas en fetos con síndrome de Down / Ultrasound features and congenital anomalies in fetuses with Down syndrome

Resumen Objetivo: Describir y analizar los hallazgos ecográficos en 97 fetos portadores de síndrome de Down (SD) confirmado. Método: Se incluyeron todas las gestantes con diagnóstico prenatal de SD de nuestro centro, realizado por cariograma o reacción en cadena de la polimerasa cuantitativa fluorescente para aneuploidía. Se analizaron los informes genéticos y ecográficos, y se realizó un seguimiento posnatal. Resultados: De los 97 casos de SD, el 73% de los diagnósticos fueron entre las 11 y 14 semanas. El promedio de edad de las madres fue de 35,7 años. El 83% de los fetos con SD, evaluados a las 11-14 semanas, tuvieron una translucencia nucal ≥ 3,5 mm. Del total de los casos analizados, el 33% fueron portadores de una cardiopatía congénita, correspondiendo el 58% de estas a defectos mayores, principalmente anomalías del tabique auriculoventricular. Un 7,6% de los casos terminaron como mortinato, principalmente durante el tercer trimestre. Conclusiones: El ultrasonido es una herramienta muy sensible para la sospecha prenatal de SD y la detección de sus anomalías asociadas. Consideramos que la información aportada será útil para programar estrategias de pesquisa, organizar el control perinatal y precisar el consejo a los padres de fetos portadores de esta condición.

Abstract Objective: To describe and analyze the ultrasound findings in 97 fetuses with confirmed Down syndrome (DS). Method: All pregnant women with prenatal diagnosis of DS in our center, performed by karyotype or quantitative fluorescent polymerase chain reaction for aneuploidy, were included. Genetic and ultrasound reports were analyzed, as well as postnatal follow-up. Results: Of the 97 cases of DS, 73% of the diagnoses were between 11-14 weeks. The average age of the mothers was 35.7 years. 83% of our fetuses with DS, evaluated between 11-14 weeks, had a nuchal translucency ≥ 3.5 mm. Of the total of the fetuses analyzed, 33% were carriers of congenital heart disease, 58% of these correspond to a major defect, mainly anomalies of the atrioventricular septum. 7.6% of cases ended as stillbirth, mainly during the third trimester. Conclusions: Ultrasound is a very sensitive tool for prenatal suspicion of DS and the detection of its associated abnormalities. We believe that the information provided will be useful to program screening strategies, organize perinatal control and to counselling parents of fetuses carrying this condition.

Doppler de arteria umbilical en fetos con síndrome de Down / Umbilical artery Doppler in fetuses with Down syndrome

INTRODUCCIÓN: La aneuploidía más común entre los recién nacidos vivos es el síndrome de Down (SD). En estos niños el crecimiento está disminuido, con una frecuencia del 25% de restricción del crecimiento intrauterino, pero no se ha establecido el papel de la insuficiencia placentaria. El objetivo es estudiar la resistencia placentaria a través del Doppler de arteria umbilical con índice de pulsatilidad (IP) y el tiempo medio de desaceleración (t/2), y el posible efecto de la insuficiencia placentaria en fetos con SD. MÉTODO: Se realizó Doppler en la arteria umbilical en 78 fetos con SD, se midieron el IP y el t/2, y se compararon los resultados con los pesos de nacimiento. RESULTADOS: Se estudiaron 78 fetos con SD con 214 mediciones Doppler. El t/2 y el IP estaban alterados en el 71,5% y el 65% de las mediciones, respectivamente. La incidencia de t/2 alterado aumenta con la edad gestacional desde un 28,6% a las 15-20 semanas hasta un 89,3% sobre las 36 semanas (p < 0,01); cifras similares se observan para el IP. La clasificación de los pesos fue: 64% adecuados, 12% grandes y 24% pequeños para la edad gestacional. La última medición de t/2 antes del parto era normal en el 17% y estaba alterada en el 83%. En el caso del IP, los valores fueron normales en el 27% y anormales en el 73%. El peso de nacimiento, la edad gestacional y el porcentaje de niños adecuados para la edad gestacional eran significativamente mayores en el grupo con Doppler normal que en el grupo con Doppler alterado. El z-score del t/2 estaba marcadamente alterado (−2.23), pero el del peso de nacimiento solo estaba algo disminuido (−0,39). La mortalidad perinatal fue del 10%, significativamente mayor cuando el flujo diastólico era ausente o reverso. CONCLUSIONES: El estudio demuestra que los fetos con SD tienen una alta incidencia de alteración del Doppler umbilical para el IP y el t/2, lo cual sugiere una insuficiencia placentaria grave. Este deterioro parece iniciarse hacia el final del segundo trimestre y aumenta con la edad gestacional. Sin embargo, en estos fetos, la insuficiencia placentaria produce una ligera caída en el crecimiento fetal. Como hipótesis general pensamos que en los fetos con SD hay datos claros de insuficiencia placentaria, pero habría algún factor que les protegería de una restricción grave del crecimiento.

INTRODUCTION: The most common aneuploidy in live newborns is Down syndrome (DS), in these children growth is decreased, with a frequency of 25-36% of fetal growth restriction (FGR); however, it is not established the role of placental insufficiency. The objective is to study the Doppler of the umbilical artery with pulsatility index (PI) and half peak systolic velocity (hPSV) deceleration time and the possible role of placental insufficiency in fetuses with DS. METHOD: Doppler was performed in fetuses with DS, the umbilical artery and IP and hPSV were measured, and the results were compared with birth weights. RESULTS: 78 fetuses with DS were studied with 214 Doppler measurements. hPSV and the IP were altered in 71.5% and 65% of the measurements; the incidence of abnormal hPSV increases with gestational age from 28.6% between 15 to 20 weeks, to 89.3% over 36 weeks (p < 0.01), similar figures are observed with respect to the PI. The weight classification was: 24% of FGR, 12% of great for age and 64% of adequate for gestational age (AGA). The last measurement of hPSV before delivery was normal in 17% of the fetuses and was abnormal in 83%, in the case of PI the normal and abnormal values were 27 and 73%, respectively. Birth weight, gestational age, and the percentage of AGA children were significantly higher in the normal Doppler group than in the abnormal Doppler group. The hPSV z-score was markedly altered (−2.23), but the birth weight z-score is slightly decreased (−0.39). Perinatal mortality is 10% and is significantly higher when diastolic flow is absent or reverse. CONCLUSIONS: The study shows that DS fetuses have a high incidence of abnormal umbilical Doppler measured with IP and hPSV, which suggests severe placental insufficiency, this deterioration seems to start towards the end of the second trimester and increases with gestational age. However, in these fetuses, placental insufficiency causes a discrete drop in fetal growth. As a general hypothesis, we think that there is clear evidence of placental insufficiency in fetuses with DS, but there would be some factor that would protect these fetuses from severe growth restriction.

Rol de los marcadores ecográficos secundarios de primer trimestre para la detección de trisomía 21 / Role of first trimester secondary ultrasound markers for trisomy 21 detection

OBJETIVO: Analizar los resultados de los marcadores ecográficos secundarios (hueso nasal, onda a del ductus venoso y regurgitación tricuspídea) y valorar su efectividad para la detección de trisomía 21 y su utilidad para la reducción del número de pruebas invasivas. MÉTODOS: Tras la realización del test combinado de primer trimestre a toda paciente con un riesgo entre 1/101-1/1000 se realizó la valoración de los marcadores secundarios. RESULTADOS: Desde Enero de 2014 a Mayo de 2015 se realizaron 2.660 test combinados del primer trimestre valorándose la edad materna, la traslucencia nucal y la PAPP-A y ßhCG, teniendo una sensibilidad del 90% y una tasa de falsos positivos del 3,2%. Hubo 10 fetos con trisomía 21. La sensibilidad de hueso nasal, ductus venoso y regurgitación tricuspídea fue del 22,2%, 50% y 50% y la especificidad del 99,8%, 96,9% y 98,8% respectivamente. La sensibilidad global del test contingente fue del 90%, con una reducción de la tasa de falsos positivos al 1,6%, lo que se reduciría de 171 a 148 el número de amniocentesis. CONCLUSIÓN: El test contingente es una buena herramienta para reducir la tasa de falsos positivos respecto al test combinado sin disminuir la tasa de detección y con ello reducir la tasa de pruebas invasivas.

AIMS: To analyze the results of the secondary sonographic markers (nasal bone, wave ductus venosus and tricuspid regurgitation) and evaluate its effectiveness for the detection of trisomy 21 and thus reduce the number of invasive tests. METHODS: After completing the first trimester combined test, all patients with a risk between 1/101-1/1000 were evaluated the secondary sonographic markers. RESULTS: From January 2014 to May 2015 2660 combined test being assessed maternal age, nuchal translucency and PAPP-A and ßhCG were performed, with a sensitivity of 90% and a false positive rate of 3.2%. 10 fetuses with trisomy 21 were observed. The sensitivity of nasal bone, ductus venosus and tricuspid regurgitation was 22.2%, 50% and 50% and specificity was 99.8%, 96.9% and 98.8% respectively. The overall sensitivity of contingent test was 90%, with a reduction in false positive rate to 1.6%, which would decrease the number of amniocentesis from 171 to 148. CONCLUSION: The contingent test is a good tool to reduce the rate of false positives with respect to the combined test without decreasing the detection rate and thereby reduce the rate of invasive testing.

Prenatal Diagnosis of Transient Abnormal Myelopoiesis in a Down Syndrome Fetus

We report a case of transient abnormal myelopoiesis in a Down syndrome fetus diagnosed at 28(+3) weeks of gestation that rapidly progressed to intrauterine death 10 days later. Fetal hepatosplenomegaly with cerebral ventriculomegaly, although not specific, may be a suggestive finding of Down syndrome with transient abnormal myelopoiesis. Prompt fetal blood sampling for liver function test and chromosomal analysis are mandatory for early detection and management.

Nasal bone hypoplasia in trisomy 21 at 15 to 24 weeks' gestation in A high risk Thai population.

OBJECTIVE: To assess the utility of nasal bone hypoplasia in the detection of fetuses with trisomy 21 in the second trimester in a high risk Thai population. MATERIAL AND METHOD: A prospective study involving pregnant women undergoing amniocentesis due to increased risk of aneuploidy from January 2005 to December 2005. Fetal biometry and nasal bone measurements were obtained at the time of amniocentesis. Linear regression model and diagnostic tests were analyzed using the SPSS computer program. RESULTS: A total of 407 fetuses were evaluated. In euploid fetuses, the Nasal Bone Length (NBL) increased linearly with advancing gestational age. Fetuses with Down syndrome had a significantly higher proportion of NBL below the 5th centile when compared with normal fetuses (p < 0.05). The optimal nasal bone threshold associated with trisomy 21 is a BiParietal Diameter/Nasal Bone Length (BPD/NBL) ratio of 10 or greater, yielded a sensitivity of 80%, specificity of 86% for detection of trisomy 21. CONCLUSION: Nasal bone hypoplasia is associated with an increased risk of Down syndrome in the presented population.

Nomogram of nuchal fold thickness of Thai fetuses.

The aim of the study was to establish normal values of nuchal fold thickness during 14-21 weeks of pregnancy. Three hundred Thai pregnant women before 12 weeks of gestation were recruited. Gestational age was determined by last menstrual period and confirmed by crown-rump length. Subjects with date-size discrepancy of more than 7 days were excluded from the study. Nuchal fold thickness was measured twice, first during 14-17 weeks, and then during 18-21 weeks. Five hundred and nine measurements were obtained. Nomogram of nuchal fold thickness was constructed. Mean values of nuchal fold thickness increased steadily from 2.59 +/- 0.77 millimeters (mm) at 14 weeks to 4.12 +/- 0.98 mm at 21 weeks. Average rate of increase were 0.22 mm per week. In conclusion, nuchal fold thickness increased with advancing gestational age from 14 to 21 weeks of pregnancy. Different normal cut-off levels for each gestational week may be more appropriate for screening of fetal Down syndrome in Thai pregnant women.

Nomograms of fetal nuchal fold thickness for early detection of Down syndrome.

A prospective study was undertaken in North India to find the normative data on the nuchal fold thickness of randomly selected 150 fetuses between 16-22nd week of gestation. The data revealed that the width of nuchal fold thickness ranged between 2-5 mm. The mean for 16-18, > 18-20, and > 20-22 week's gestation was 2.6 +/- 0.2, 3.8 +/- 0.9, and 4.0 +/- 0.8 mm respectively. In one fetus nuchal fold thickness was 6mm at 18 weeks (> 2SD above the normal value) and thus Down Syndrome was suspected. This was later confirmed by amniocentesis and karyotyping.