Markers biochimici e translucenza nucale.

Markers biochimici e
translucenza nucale.
Lorenza Driul
L'incredibile impresa, illegale, di alcuni fotografi russi che hanno scalato la Grande
Piramide di Cheope a Giza in notturna. Le guardie hanno chiuso il sito al tramonto e
loro, per quattro ore, si sono nascosti per poi raggiungere la vetta e scattare le
incredibili foto della spianata. Scalare la piramide può costare una punizione con
detenzione, da uno a quattro anni: "Ma ne valeva la pena, mai stato così felice", ha
affermato uno dei fotografi.
Anno1970: maternal age
Shuttelworth,1909:
“…in un considerevole numero – da metà ad un terzo – le
madri nel periodo di gestazione erano in prossimità del
climaterio…”
Maternal age
The risk for trisomy 21:
Increases with maternal age
Decreases with gestational age because about 30% of affected fetuses die between
the 12th and 40th week of pregnancy
Maternal age
Other defects
The risk for trisomies 18 and 13 increases with maternal age and decreases with
gestation. The rate of fetal death between the 12th and 40th week is about 80%
Maternal age
Other defects
Turner syndrome is unrelated to maternal age. The rate of fetal death between the
12th and 40th week is about 80%. The prevalence is about 1 in 1500 at 12 weeks and
1 in 4000 at 40 weeks.
Triploidy is unrelated to maternal age. The prevalence at 12 weeks is about 1 in 2000
but it is highly lethal and is very rarely observed in live births
Anno1970:maternal age
Anno1980: maternal serum biochemistry
Anno1990: first trimester
and NT.
Increased NT
Trisomy 16 mouse, which is a good animal model
for human trisomy 21, has defects of the heart and
lymphatic vessels
On days 14-16 of fetal life, there is a subcutaneous
collection of fluid in the back of the neck.
Nuchal translucency
Definition
 Nuchal translucency (NT) is the sonographic appearance of a collection of fluid
under the skin behind the fetal neck in the first trimester of pregnancy.
 The term translucency is used, irrespective of whether it is septated or not and
whether it is confined to the neck or envelopes the whole fetus.
 The incidence of chromosomal and other abnormalities is related to the size, rather
than the appearance of NT.
 During the second trimester, the translucency usually resolves and, in a few cases,
it evolves into either nuchal edema or cystic hygromas with or without generalized
hydrops.
Genetic syndromes reported in fetuses
with increased nuchal translucency
thickness
AchondrogenesisFowler syndromeOsteogenesis imperfecta type
II*Achondroplasia*Fryn syndromePerlman syndromeAdrenal
hyperplasia*GM1-Gangliosidosis*Roberts syndromeAsphyxiating thoracic
dystrophyHydrolethalus syndromeRobinow syndromeBeckwith–Wiedemann
syndromeHypochondroplasiaShort-rib polydactyly syndromeBlackfanDiamond anemiaHypophosphatasiaSmith–Lemli–Opitz
syndrome*Blomstrand osteochondrodysplasiaInfantile polycystic kidney
diseaseSpinal muscular atrophy type 1*Campomelic dysplasiaJarcho–Levin
syndromeStickler syndromeCHARGE associationJoubert
syndromeThalassaemia-a*Cleidocranial dysplasiaLong chain HAD
deficiency*Thanatophoric dysplasia*Cornelia de Lange
syndromeLymphedemaTreacher Collins syndromeDi George
syndrome*Meckel–Gruber syndromeTrigonocephaly ‘C’
syndromeDyserythropoietic anemiaMucopolysaccharidosis type VII*VACTER
associationEctrodactyly-cleft palate syndromeMyotonic dystrophy*Vitamin D
resistent ricketsErythropoietic porphyriaNance–Sweeney syndromeZellweger
syndrome*Fanconi anemiaNephritic syndrome*
Fetal akinesia deformation sequenceNoonan syndrome*
Translucenza nucale (NT)
•  La reale patogenesi dell’aumento dello spessore
retronucale non è ancora chiarita.
•  Le ipotesi prevalenti riguardano:
–  difetti di funzionamento o di struttura dell’apparato
cardiovascolare o linfatico;
–  alterazioni della matrice extracellulare documentate dall’aumento
del collagene VI e dell’acido ialuronico nel sottocute.
Increased fetal NT is associated with a heterogeneous group of conditions suggesting
that there may not be a single underlying mechanism for the collection of fluid under
the skin of the fetal neck.
 
 
 
 
Others possible mechanisms include:
Venous congestion in the head and neck
Fetal anemia
Fetal hypoproteinemia
Fetal infection
Nuchal translucency
The NT thickness in euploid fetuses increases with fetal CRL
In 75-80% of trisomy 21 fetuses the NT thickness is above the 95th centile of the normal
range.
Fetal heart rate
In normal pregnancy, the FHR increases
from about 110 bpm at 5 weeks of gestation to
170 bpm at 10 weeks and then gradually
decreases to 150 bpm by 14 weeks.
  In trisomy 21 the FHR is mildly increased and is
above the 95th centile in about 15% of cases.
  In trisomy 18 the FHR is mildly decreased and is
below the 5th centile in about 15% of cases.
  In trisomy 13 the FHR is substantially
increased and is above the 95th centile in
85% of cases.
LA FREQUENZA
CARDIACA FETALE
Inclusion of FHR in first-trimester combined sonographic and biochemical
screening for chromosomal abnormalities has a small impact on the detection of
trisomies 21 and 18 but a major improvement in the detection of trisomy 13
In addition, inclusion of FHR is important in distinguishing between trisomy 18 and
13, which are otherwise similar in presenting with increased fetal NT and decreased
maternal serum free β-hCG and PAPP-A.
Requisiti per la certificazione….
Corso teorico online -ecografia delle 11-13 s(www.fetalmedicine.com).
Invio di un book fotografico di 3 immagini con la determinazione
corretta della NT
Prova pratica con la supervisione di un esaminatore autorizzato dalla
Fetal Medicine Foundation.
“Certificato di Competenza della Fetal Medicine
Foundation nell’ ecografia delle 11–14 settimane
per lo screening delle patologie cromosomiche ”
TRANSLUCENZA NUCALE: Training ed assicurazione della qualità
Gli ecografisti che effettuano l’ ecografia NT devono ricevere un adeguato training e
i risultati devono essere soggetti ad un controllo rigoroso.
La “Fetal Medicine Foundation” ha introdotto un processo di training e certificazione per aiutare a
stabilire elevati standard ecografici a livello internazionale
Il “Certificato di Competenza nell’ ecografia delle 11–14 settimane” viene rilasciato a quegli
ecografisti che sono in grado di effettuare un esame di alto livello e possono dimostrare una
buona conoscenza nel diagnosticare e gestire le condizioni identificate mediante l’ ecografia
Ottenuto il certificato: libero utilizzo del FMF software per il calcolo del rischio di anomalie
cromosomiche per 12 mesi
Inoltre, il successo di un programma di screening necessita della presenza di un sistema di costante
controllo dei risultati (audit) e continua valutazione della qualità delle immagini.
Anno1990: first trimester
and NT.
SENSIBILITA’ del “test combinato” del primo
trimestre nei maggiori studi pubblicati
Studio
SURUSS
J Med Screen 2003
FASTER
N Engl J med 2005
OSCAR
Ultrasound Obstet
Gynecol 1999
BUN
N Engl J Med 2003
Totale
N°
pazienti
N° casi di
S.Down
Detection rate
47.053
101
83%
33.557
84
85%
15.030
82
90%
8.216
61
79%
103.856
328
84% (95%CI:
79.7-87.0)
Serum biochemistry
Screening biochimico
Screening biochimico
In trisomy 21 pregnancies maternal serum free ß-hCG is about twice as high and PAPP-A is reduced to about
half compared to chromosomally normal pregnancies
Serum biochemistry
 The measured concentration of free ß-hCG and
PAPP-A is influenced by the machine and
reagents used, gestational age, maternal weight,
ethnicity, smoking status and method of
conception.
• In the calculation of accurate patient-specific
risks it is necessary to make adjustments in the
measured free ß-hCG and PAPP-A. Each
measured level is first converted to a multiple of
the expected normal median (MoM) specific to a
pregnancy of the same gestation, maternal
weight, smoking status, ethnicity and method of
conception.
• In Black women the PAPP-A level is about 60%
higher than in White women. Failure to take into
account ethnic origin would result in substantial
underestimate of the true risk of trisomy 21 in
Black women.
• In women who smoke and those conceiving by
IVF serum PAPP-A is decreased and this could
be misinterpreted for increased risk for trisomy 21
and a substantial increase in false positive rates.
Serum biochemistry
In trisomy 21 pregnancies:
 Free ß-hCG is higher than in euploid pregnancies and the difference between the
two is higher at 13 than at 11 weeks
 Serum PAPP-A is lower than in euploid pregnancies and the difference between
the two is higher at 11 than at 13 weeks
 The difference from euploid pregnancies in PAPP-A at 11 weeks is greater than
the difference in ß-hCG at 13 weeks and therefore the overall performance of
biochemical screening is better at 11 than at 13 weeks.
The concentration of ADAM12-S increased from 8
to 11 week and was negatively correlated with the
maternal weight.
•  Maternal serum levels
of PLGF are decresead
in preeclampsia and
SGA
•  Trisomy 21?
PLGF at 8-13 w is reduced
Timing of ultrasound and blood
testing within the first trimester
• 
• 
• 
• 
one-stop clinics (OSCAR) (Bindra et al, 2002; Spencer et al. 2000)
12 weeks (>fetal anatomy)
30 min
Detection rate 90%, false-positive rate 5%
• 
• 
• 
• 
Two separate visits (Borrel et al. 2004; Wright et al.2010)
9-10 weeks
12 weeks
Detection rate 93-94%, false-positive rate 5%
 
 
 
• 
PAPP-A at 9 weeks
Scan 12 weeks
Free beta-HCG at the time of the scan at 12 weeks or 13 weeks
Detection rate 95%, false-positive rate 5%
The cost and patient acceptability
of the alternativ policies of first
trimester testing will depend on the
existing infrastructure of
antenatal care.
The potential advantage of the two or
three-stage screening in terms of
detection rate may be eroded by the
likely incresead non-compliance
with the additional steps.
Screening integrato del primo e del secondo trimestre
•  approccio «integrato» allo screening utilizza i marcatori del
primo e del secondo trimestre per personalizzare il rischio di
SD legato all’età materna.
  Se l’obiettivo è quello di fornire la più alta sensibilità con il più basso tasso di
test falsi positivi, il test integrato è quello più efficace.
  Le critiche: ansia generata dall’attesa di 3-4 settimane tra il primo e il
secondo prelievo, la mancata possibilità di sottoporsi a CVS, eventualità che
la paziente eluda la seconda parte del test. Il risultato viene reso noto solo
dopo il prelievo del secondo trimestre
New ultrasound markers
Assessment of the new markers improves the performance of combined screening
by increasing the detection rate and reducing the false positive rate
Examination of the new markers requires appropriate training of sonographers and
Certification of their competence in carrying out these scans
The new markers can be assessed in all patients or only in the 15% of the total
with an intermediate risk (1 in 51 to 1 in 1000) after combined screening.
  Nasal bone
  Facial angle
  Ductus venosus flow
  Tricuspid flow
Fetal hepatic artery (?)
DR
False-positive rate
Nasal bone
At 11-13 weeks the nasal bone is considered to be absent in about:
Euploid fetuses
1-3%
Fetuses with trisomy 21 60%
Fetuses with trisomy 18 50%
Fetuses with trisomy 13 40%
Absence of the nasal bone is more common if:
  The gestation is 11 than 13 weeks
  The fetal nuchal translucency is high
  The mother is Black
Angolo facciale
Reversed a-wave is associated with
increased risk for:
 Chromosomal abnormalities
 Сardiac defects
 Fetal death
At 11-13 weeks reversed a-wave is found
in about:
Euploid fetuses
3%
Fetuses with trisomy 21 65%
Fetuses with trisomy 18 55%
Fetuses with trisomy 13 55%
Assessment of ductus venosus a-wave improves
the performance of first-trimester combined
screening:
Detection rate
95%
False positive rate 2.5%
Mavrides et Al.. BJOG September 2002; 109:1015–1019.
Rigurgito tricuspidale
  Normal profile with no regurgitation during systole
  Regurgitation during approximately half of systole and with a velocity more than
60 cm/s
At 11-13 weeks tricuspid regurgitation is found in about:
Euploid fetuses
1%
Fetuses with trisomy 21
55%
Fetuses with trisomy 18
30%
Fetuses with trisomy 13
30%
Tricuspid regurgitation is more common if:
  The gestation is 11 than 13 weeks
  The fetal nuchal translucency is high
Falcon et Al. Ultrasound Obstet Gynecol 2006; 27:
609-612
Increased NT
Example: fetus with NT of 3.5 - 4.4 mm
  In 100 fetuses with NT of 3.5 - 4.4 mm diagnosed at 12 weeks 20 would have a
chromosomal abnormality and 80 would be euploid.
  In the 80 euploid fetuses there would be 2 (2.5%) that would die in the
subsequent few weeks
  In an additional 8 of the 80 euploid fetuses (10%) there would be a major defect
  The remaining 70 euploid fetuses with no major defects would be live born and
healthy
This is found in about 1% of
pregnancies.
The risk of chromosomal defects is very
high and the first line of management of
such pregnancies should be the offer of
chorion villous sampling (CVS) for fetal
karyotyping. In patients with a family
history of genetic syndromes that can be
diagnosed by DNA analysis, the CVS
sample can also be tested for these
syndromes.
A detailed scan is also carried out a couple
of weeks later and again at 20 weeks
If no obvious abnormalities are seen and the
NT has completely resolved the parents
should be reassured that their baby is likely
to be live born and develop normally.
Increased NT NT 3.5 mm or more
If no obvious abnormalities are seen but there is persistence of increased NT at
14-16 weeks and evolution to nuchal edema or hydrops fetalis at 20-22 weeks, it is
possible that there is congenital infection or a genetic syndrome.
Maternal blood should be tested for toxoplasmosis, cytomegalovirus, and parvovirus
B19. Follow-up scans should be carried out every 4 weeks to define the evolution of
the edema.
Consideration should be given to DNA testing for certain genetic conditions, such as
Noonan syndrome, even if there is no family history for these conditions.
There is a 10% risk of perinatal death or a live birth with a genetic syndrome that
could not be diagnosed prenatally.
The risk of neurodevelopmental delay in the survivors is 3-5%.
Sindrome Noonan
  1/1.000 e 1./2500
  eterogeneità genetica- (50%) Mutazioni a carico del gene PTPN11 sul
cromosoma 12
  Ereditarietà autosomica dominante con nuove mutazioni sporadiche
  Bassa statura
  Facies tipica
  Cardiopatie congenite
Segni ecografici:
  Igroma cistico (NT aumentata)
  Cardiopatie congenite: stenosi
polmonare cardiomiopatia
  Polidramnios
  Diagnosi clinica e post-natale
  Diagnosi invasiva prenatale conferma solo nel 50%
Jeanty P., Silva S.R., Leite J. Noonan Syndrome. Thefetus.net 2006-01-18.
ASTRAIA
Per il calcolo RSD presso la nostra Clinica
utilizziamo il programma ASTRAIA che si basa
sugli algoritmi sviluppati dalla Fetal Medicine
Foundation London (FMF).
Stratificazione del rischio
> 1/1000
>1/250 - <1/1000
>1/250
ACOG 2007 Committee on practice
bulletins No 77
 
 
 
Combined 1st trimester screening is an effective
screening test, better than NT alone
Women with positive first trimester screens
should be offered counseling and an option of
CVS or 2nd trimester amniocentesis
Training/standardization need for NT
 
 
Integrated 1st + 2nd screening is more sensitive
than first trimester screening alone
Serum integrated (1st) screening is a viable option if
NT is unavailable
Modalità di esecuzione dell’esame
• La misurazione della translucenza nucale deve
essere effettuata solo alle donne che informate
acconsentano a sottoporsi all’esame e solo da
operatori accreditati da Società nazionali e
internazionali, i quali abbiano ricevuto un
adeguato training teorico e pratico, e siano
sottoposti a controlli periodi di qualità.
Le possibilità e i limiti della translucenza come
test di screening per le anomalie cromosomiche
devono essere illustrate in modo comprensibile
alla donna, preferibilmente con foglio informativo
scritto.
• Il referto scritto deve comprendere il rischio
stimato per trisomia 21 (evidenza II-a, livello
raccomandazione A)
• Le pazienti il cui rischio risulta elevato devono
essere informate dell’indicazione a sottoporsi alla
diagnosi prenatale invasiva.
Diagnosi prenatale della
sindrome di Down
  La misurazione della translucenza nucale isolata non è raccomandata per
individuazione della sindrome di Down.
  Per le donne che hanno scelto un test combinato deve essere eseguito tra 11+0
e 13+6 settimane.
  Nel primo trimestre il test combinato è risultato accurato per la sindrome
di Down.
  Il test integrato è il test con il miglior rapporto beneficio/danno; offrire la
migliore accuratezza diagnostica e risulta associato a una perdita inferiore di
feti sani.
  Nel secondo trimestre il quadruplo test ha la migliore performance ma la sua
fattibilità è limitata non sempre l’inibina A è disponibile.
  La misurazione della translucenza nucale per individuare anomalie
fetali non è raccomandata
Materiali e metodi
Risultati
 
 
The mean maternal age is 32.01 years (±5.39), 82% are
nulliparous, and the mean gestational age at delivery is 38.48
weeks (±2.81). The prevalence of pre-eclampsia is 1.7%, and
in 11% of cases presents an associated IUGR. Low PAPP-A
MoM value results to be a risk factor for pre-eclampsia in
monovariate analysis (p<0.05), and also after correction for
fetal weigth MoM value, placental MoM value, and maternal
age (p<0.05). The AUC of PAPP-A MoM ROC results to be
64% (CI.95 53%-76%) and the best cut-off to predict preeclampsia is 0.9 MoM (with specificity of 56% and sensitivity
74%).
But creating a multivariate model with the following risk
factors available during the first-trimester screening visit
(maternal age, BMI, race, academic degree, PAPP-A MoM)
we obtain an AUC of 81% (CI.95 71%-92%) (p<0.05).
Predittività per pre-eclampsia
 
 
PAPP-A MoM value is a predictive
factor for pre-eclampsia but presents
a low specificity, and in fact it is
known to be predictive also for other
pregnancy diseases related to
placenta.
But the information available during
the first-trimester trisomy screenig
(maternal age, BMI, race, academic
degree, PAPP-A MoM) result in a
multivariate model accurate to
predict the development of preeclampsia at term in a population of
singleton pregnancies with a high
prevalence of nulliparous women..
CONCLUSIONII
…The future of
prenatal diagnosis….
…..DNA fetale….
• Fetal anatomy?
• Doppler studies?(ductus venosus or tricuspid
regurgitation and increased risk for cardiac defects)
Markers:
• Preterm delivery
• Preeclampsia
• Gestational diabetes
• Small for gestational age
Hippocrates
…We should learn the past and research the present to predict the
future…