Post on 04-Aug-2020
Dr. Masami Yamamoto Clínica Universidadde los Andes
Dr. Masami YamamotoMedicina FETAL
Clínica Universidad de los Andes
Screening de Aneuploidias
Dr. Masami Yamamoto Clínica Universidadde los Andes
Control prenatal
PRENATAL DIAGNOSIS
Prenat Diagn 2011; 31: 3–6.Published online in Wiley Online Library
(wileyonlinelibrary.com) DOI: 10.1002/pd.2685
EDITORIAL
A model for a new pyramid of prenatal care basedon the 11 to 13 weeks’ assessment
Kypros H. Nicolaides1,2*
1Harris Birthright Research Centre of Fetal Medicine, King’sCollege Hospital, London, UK2Department of Fetal Medicine, University College Hospital, London, UK
One century ago it was recognized that with the methodsand material at our disposal we were not making allthe progress possible toward solving many problemsof prenatal diagnosis and treatment (Ballantyne, 1901,1921). In order to achieve these objectives it was urgedthat a new means of investigation should be undertakenwhich had not yet been tried, at least not yet attemptedon a large scale and in a systematic fashion. This ledto the introduction of prenatal care which constituted amajor advance in the care of pregnant women and playeda pivotal role in the substantial reduction in maternal andperinatal mortality achieved during the last century.
In 1929, the Ministry of Health in the UK issueda Memorandum on Antenatal Clinics recommendingthat women should first be seen at 16 weeks, then at24 and 28 weeks, fortnightly thereafter until 36 weeksand then weekly until delivery (Figure 1) (Ministry ofHealth Report, 1929). No explicit rationale was offeredfor either the timing or clinical content of visits, yetthese guidelines established the pattern of prenatal careto be followed throughout the world until now. Thehigh concentration of visits in the late third trimesterimplies that most complications occur toward the endof pregnancy and most adverse outcomes cannot bepredicted from the first trimester. However, is this reallythe case? Scientific advances in the last 20 years haveraised the hope that many pregnancy complications arepotentially detectable from at least as early as the 12thweek of gestation. It has become apparent that mostmajor aneuploidies can be identified at 11 to 13 weeks’gestation by a combination of maternal characteristics,ultrasound findings and biochemical testing of maternalblood. It is also becoming increasingly apparent thatan integrated first hospital visit at 11 to 13 weekscombining data from maternal characteristics and historywith findings of biophysical and biochemical tests candefine the patient-specific risk for a wide spectrumof pregnancy complications, including miscarriage andfetal death, preterm delivery, preeclampsia, gestationaldiabetes, fetal growth restriction and macrosomia.
*Correspondence to: Prof. Kypros H. Nicolaides, Harris BirthrightResearch Centre for Fetal Medicine, King’s College Hospital,Denmark Hill, London SE5 9RS, UK.E-mail: kypros@fetalmedicine.com
Figure 1—Pyramid of prenatal care: past (left) and future (right)
FETAL ANEUPLOIDIES
We have learnt that about 90% of fetuses with major ane-uploidies can be identified by a combination of maternalage, fetal nuchal translucency (NT) thickness and mater-nal serum-free ß-hCG and PAPP-A at 11 to 13 weeks(Nicolaides, 2011). Improvement in the performance offirst-trimester screening can be achieved by first carry-ing out the biochemical test at 9 to 10 weeks and theultrasound scan at 12 weeks and second, inclusion inthe ultrasound examination assessment of the nasal boneand flow in the ductus venosus, hepatic artery and acrossthe tricuspid valve. A similar performance of screeningcan be achieved by examining the additional ultrasoundmarkers in all cases and by a contingent policy in whichfirst-stage combined screening classifies the patients ashigh-, intermediate- and low-risk and the new markersare examined only in the intermediate-risk group whichis then reclassified as low- or high-risk.
FETAL STRUCTURAL ABNORMALITIES
We have learnt that at the 11 to 13 weeks’ scan itis possible to diagnose or suspect the presence ofmost major abnormalities, which are either lethal orassociated with severe handicap, so that the parentscan have the option of earlier and safer pregnancytermination. Major fetal abnormalities fall into essen-tially three groups in relation to whether they can bedetected at the 11 to 13 weeks’ scan (Syngelaki et al.,2011): first, those which are always detectable abnor-malities, including body stalk anomaly, anencephaly,
Copyright Ó 2011 John Wiley & Sons, Ltd. Received: 30 November 2010Revised: 5 December 2010
Accepted: 5 December 2010
antes ¿quizás?NICOLAIDES. PRENAT DIAGN . 2011
EVALUACIÓN PRECOZ RIESGO
INTERVENCION
11-14 sem
22-24 sem
28-32 semanas
Ecografias recomendadas
Translucencia nucal
Marcadores 1er TrimAnomalías fetales
Riesgo
Aborto Múltiples
&
Corionicidad
Pre-eclampsia /
RCF
ECOGRAFÍA 11-14 SEMANAS
Dr. Masami Yamamoto
Dr. Masami Yamamoto
Dr. Masami Yamamoto Clínica Universidadde los Andes
Dr. Masami Yamamoto
Screening por Edad materna:
Criterio: >35 años
Ejemplo1: 10 millones de mujeres, 5% de >35 años
Ejemplo 2: 10 millones de mujeres, 10% de >35 años
Edad
≤35
>35
Población
9.500.000
500.000
Prob. T21
1/1000
1/200
Casos T21
9.500
2.500
Edad
≤35
>35
Población
9.000.000
1.000.000
Prob. T21
1/1000
1/200
Casos T21
9.000
5.000
Efecto de la mayor
Edad materna
Tamizaje Prenatal: Sd Down
• Ecografía 11-14 semanas
• Marcadores secundarios
• Doppler Tricuspídeo
• Doppler Ductus Venoso
• Hueso nasal
• Translucencia nucal: principal marcador
Dr. Masami Yamamoto
Definición de TN
aumentada:
> p95
Dr. Masami Yamamoto
+1/20
Tamizaje Prenatal: Sd Down
• Ecografía 11-14 semanas
• Marcadores secundarios
• Doppler Tricuspídeo
• Doppler Ductus Venoso
• Hueso nasal
• Translucencia nucal: principal marcador
Tamizaje Prenatal: Sd Down
• Ecografía 11-14 semanas
• Marcadores secundarios
• Doppler Tricuspídeo
• Doppler Ductus Venoso
• Hueso nasal
• Translucencia nucal: principal marcador
Tamizaje Prenatal: Sd Down• Ecografía 11-14
semanas• Marcadores secundarios
• Doppler Tricuspídeo
• Doppler Ductus Venoso
• Hueso nasal
• Translucencia nucal: principal marcador
Bioquimica Materna
o
Marcadores Sericos
Dr. Masami Yamamoto Clínica Universidadde los Andes
Screening de aneuploidias
Bioquímica materna
PAPP-A
βHCG libre
LHR =4
Dr. Masami Yamamoto Clínica Universidadde los Andes
Metodo Matemático
estimación del riesgoedad materna
*base X
Eco
LR
Marcardores
LRX
= Probabilidad Final
Dr. Masami Yamamoto Clínica Universidadde los Andes
Ejemplo:
Mujer 36 años
1/196 X
Eco
1/98 (LR =2)
Marcardores
1/65 (LR =3)X
= Probabilidad Final
2 x 3 x 1/196
Dr. Masami Yamamoto Clínica Universidadde los Andes
Mujer 36 años
1/196 X
Eco
1/98 (LR =2)
Marcardores
1/65 (LR =3)X
= 1/196 x 2 x 3Probabilidad Final
6/196=1/32
Dr. Masami Yamamoto Clínica Universidadde los Andes
Método Tasa de
Detección
%
screening
positivo
Edad >35 años 30% 5%
Edad +
Marcadores séricos 2°T
60% 5%
Edad +
Translucencia nucal
80% 3%
Edad + TN + MS 1er T 85% 2%
Edad + TN + Hueso Nasal 90% 2%
Edad+TN+HN+MS1erT 95% 2%
Dr. YM Dennis Lo
• Presence of fetal DNA in maternal plasma and serum.
• The Lancet, Vol 350; 9076: 485-487
• August 1997
Procedimientos invasivos
Para confirmacion
Edad gestacional
AMNIOCENTESIS
BIOPSIA DE VELLOSIDADES
CORDOCENTESIS
11 16 20 40
AMNIOCENTESISBVC
Dr. Masami Yamamoto Clínica Universidadde los Andes
Amniocentesis
N=4374
early:12 (11-13) late:15(15-17)N=2183 N=2185
Abortos 5.6% 2.9% p=0.012
Pies Bots 1.3% 0.1% p=0.0001
RPM 3.5% 1.7% p=0.0007
Dificultad TEC 10% 4 % p<0.001
2° Proced. 3% 0.4% p<0.001
CEMAT, Lancet 1998
AMNIOCENTESIS
12 vs 15 semanas
Cavidad Amniotica a 11 semanas
Amniocentesis precoz puede
no entrar, o desgarrar la membrana.
Biopsia de vellosidades coriales
(BVC)
Doble aguja
Photo aspi ++
Incidencia general 1 / 5000
BVC 1 / 200-1500
Amputation 8 wks
Terminal phalanges 10 wksFirth 1994
•hipoperfusion
• Embolizacion
•Vasoactivos
Reduccion de miembros
Apodia
Acheira
Amelia
Hemimelia
Reduccion luego de BVC
(n 130.839)L
RD
/10
.000
EG Jackson, 1993
5,834,8
4,2 4
0
2
4
6
8
< 10 10 11 > 11
Dr. Masami Yamamoto Clínica Universidadde los Andes
Cordocentesis
amniocentesis
biopsia de
vellosidades
coriales
cordocentesis
Riesgo de aborto 0,5 a 1% 1 a 2% 2 a 25%
EG 15 semanas 11 a 14 semanas 24 o mas
Mosaicismo
placentarioRaro 1 a 2% 2%
muestra amniocitos vellosidades sangre fetal
RESUMEN
• Modelo de screening en base a eco y procedimientos
confirmatorios tiene riesgos.
• Ecografia y marcadores tienen falsos postivos 2 a 5% de pob.
• El proceso de screening require operadores expertos en
ecografia y conocimiento de valores diagnosticos, para reducir
desinformacion.
• La instauracion de un protocol de screening a larga escala
producira exceso de perdidas fetales.
Dr. Masami Yamamoto Clínica Universidadde los Andes
Gracias por su atención
Y gracias por su atención