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Early Prenatal Screening in Primary Care

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Title: Early Prenatal Screening in Primary Care


1
Early Prenatal Screening in Primary Care
  • BC College of Family Physicians
  • 21st Annual Scientific Assembly
  • Ken Seethram, MD, FRCSC, FACOG
  • Pacific Centre for Reproductive Medicine
  • Clinical Lecturer, University of British Columbia
  • kseethram_at_pacificfertility.ca

2
Outline and Objectives
  • Update Family physicians on early prenatal
    screening
  • Whats new and exciting?
  • 1st and 2nd trimester screening strategies
  • ACOG and SOGC guidelines
  • What will your patients want, and where to get
    it?
  • Presentation pacificfertility.ca

3
One thing to keep in mind
  • Screening is Simple
  • Know whats there
  • Find out what your patients wish
  • Put the two together

4
History A Canadian Invention
  • Medical ultrasound is derived from Sound
    Navigation and Ranging discoveries (SONAR)
  • First SONAR was built in the USA by Canadian
    Reginald Fessenden, 1914

5
Life Magazine in 1954 The Somascope is a water
immersion motorised B-mode scanner Posakony was
the subject and his scanned kidney can be seen on
the oscilloscope screen
6
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7
Early Prenatal Screening
  • What are we screening for?
  • Most associate prenatal screening with
    aneuploidy, commonly Trisomy 21, 18, 13, monosomy
    X
  • But there is a lot more than aneuploidy
  • Congenital defects
  • Post dates screening
  • Twin screening (chorionicity, anomalies)
  • TTTS
  • Complex congenital cardiac defects
  • Pre-eclampsia screening

8
Screening is simple there are only four ways
to check a pregnancy
  • Check the blood of the mother
  • Check the baby by sonography
  • Do both
  • Make wild assumptions without doing any of the
    above (aka voodoo)
  • Remember Screening is Simple

9
What are all of the screening options prior to 20
weeks?
NT/Nuchal Translucency NB/Nasal Bone
determination FTS serum (PAPP-A, free-beta
hCG) DV (Ductus Venosus) FMF angle
(Frontomaxillary facial angle) TR (Tricuspid
Regurgitation) Uterine artery dopplers Quadruple
screen (uE3, dimeric Inhibin-A, total hCG,
AFP) IPS (1st and 2nd combined) SIPS (1st and 2nd
serum combined) Sequential screening Contingency
Screening Detailed sonogram
10
I know what youre thinking
  • When did all this happen?
  • What ever happened to the amnio?
  • Why is he telling us that screening is simple?
  • Because it is
  • Maternal Serum
  • Ultrasound
  • or both

11
When did all this change?
  • era of age-based screening
  • recommendations began in the 1970s
  • When the statistical increase of aneuploidy
    started exceeding the risks of amniocentesis,
    that age 35 be established as a cut-off (Resta)
  • 1980s introduction of AFP screening leading to
    Triple Marker Serum screening which in
    combination with age, increased detection rates
    of DS to 50-70.
  • False positive rates ranged from 10-25,
    increasing with maternal age
  • Also 60 Detection rate for Trisomy 18

1970s
1980s
12
When did all this change?
  • 1996 introduction of Quad screen (TMS dimeric
    inhibin A).
  • Detection rate for Down syndrome increased to
    75-77 with a 5 false positive rate
  • Around the same time, a pivotal paper was
    published in 1992 in the BMJ by Nicolaides (Kings
    College, London)
  • describing nuchal translucency (NT) which gave a
    75 DR at 11-13w6d via ultrasound

1990s
13
Nuchal Translucency (NT)
14
Nuchal Translucency (NT)
-midsagittal -zoom -Settings -Calipers -Flexion -A
mnion -Size (CRL) -FMF born
15
When did all this change?
  • 1996 Nicolaides introduced first trimester
    serum (using free beta hCG and PAPP-A) to give DR
    with NT of 85-88 with a 4-5 false positive rate
  • called FTS or First Trimester screening
  • PAPP-A (pregnancy associated placental protein A,
    made by embryo and placenta, immune function,
    increases placental growth)
  • 1996-2000 numerous papers looking at combining
    1st and 2nd trimester screening
  • With serum (serum integrated pregnancy
    screening/SIPS)
  • With NT (integrated pregnancy screening/IPS)

Mid-1990s
Early 2000s
16
When did all this change?
  • 2003 Wald SURUSS Trial, compared FTS, SIPS,
    IPS, and Quad screening
  • Setting an 85 DR
  • IPS with lowest FPR (1).
  • SIPS with 2-3 FPR
  • FTS with 4 FPR
  • Quad with 6 FPR
  • NT alone with 15 FPR
  • Flaws obtaining NT was an issue

17
When did all this change?
  • 2003-2008 Nicolaides introduces a new series of
    markers to increase DR to 95-96 with 4-5 FPR in
    the first trimester
  • Nasal Bone
  • FMF angle
  • Ductus Venosus
  • Tricuspid Regurgitation

2003-2008
18
What are these exciting new markers?
  • Nasal Bone
  • 70-80 of T21 do not have nasal calcification
    (vs. 0.5 in euploidy)
  • Gives DR up to 97 with 5 FPR

19
What are the exciting new markers?
  • Ductus Venosus

20
What are the exciting new markers?
  • FMF Angle
  • Increased beyond 85? with T21

21
What are the exciting new markers?
  • Tricuspid Regurgitation

22
The new techniques
  • Blood only
  • Second Trimester Quad (16-20w)
  • First (PAPP-A 12w) Second Trimester Quad
    (16-20w)
  • Ultrasound and Blood
  • First Trimester NT (12w) SIPS
  • First Trimester NT/NB/other markers hCG/PAPP-a

QUAD
SIPS
23
All stacked up
Markers Detects? When Sensitivity FPR Name
Age Trisomy 21, 18, 13 _at_Conception/_at_Delivery 30 Archaic
Age TMS Trisomy 21, 18, 45X, NTDs 16-20w 50-70 (for DS) 10-25 TMS
Age Quad Trisomy 21, 18, ONTDs 16-20w 75-77 (for DS) 5.2 Quad
Age NTPAPP-A fßhCG Trisomies 21,18,13 11-13w6d 85-88 5 FTS
Age NT PAPP-A fß-hCGNasal bone Trisomies 21, 18, 13 11-13w6d 92-97 4-5 FTS with Nasal Bone
Age PAPP-A fß hCG Quad Trisomies 21 18, ONTDs 12w and again at 16-20w 84-86 5 SIPS
AgeNT PAPP-A Quad Trisomies 21 18,ONTDs 12w and again at 16-20w 92-96 3-5 IPS
24
Sequential versus integrated?
  • You hear the terms a lot
  • Integrated is blinded/Sequential is not
  • What is the difference?
  • Sequential screening means that people go through
    some form of 1st 2nd combined screening, but if
    their 1st marker (eg, NT) is abnormal, they are
    informed and offered invasive testing
  • Gives the benefit of identifying patients at risk
    earlier, and offering earlier testing, but at the
    cost of declining detection rates when the Quad
    is added
  • IPS currently in BC is a sequential model, and
    therefore does not perform at 92-96 DR

25
Why did 1st and 2nd trimester screening evolve
  • Largely due to a patent interest on free beta hCG
    in the US, which made FTS limited until recently
  • To maintain high DR without fb-hCG, had to
    combine NT/PAPP-A with total hCG in the Quad
    screen
  • Currently Nick Wald (SURUSS trial) holds a patent
    on any screening performed which uses 1st and 2nd
    Trimester markers

26
Moving On
  • While aneuploidy detection is important, it is
    only one of the possible array of screening
    results
  • Lets move on to other conditions that can be
    screened for

27
congenital defect screening
  • Conventional 18-20w sonograms will give
    information on anatomic defects and soft
    markers (intracardiac focus, choroid plexus
    cysts)
  • However, increasing use of sonography before 13w
    to determine
  • Limb deformities, hydrocephalus,
    holoprosencephaly, renal and GI abnormalities,
    exomphalos
  • Still 18-20w scan is best for heart, brain, spine
  • Ample evidence now that 18-20w sonogram is almost
    diagnostic for neural tube defects
  • DR90-95
  • MS-AFP DR80

28
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29
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30
post dates screening
  • Ample evidence that an early ultrasound (first
    trimester) is useful to reduce incidence of
    post-dates induction of labour and to rule out
    ectopic and multiple gestations
  • In some countries with FTS programs, the FTS is
    the only early ultrasound required, giving
    aneuploidy and other information in the single
    visit

31
twins
  • Establish Chorionicity
  • In monochorionic twins, the largest risk is that
    of twin-twin transfusion syndrome (TTTS)
  • Available evidence suggests that monochorionic
    twins should share the same NT and, if not, this
    is an early sign of impending severe TTTS
  • Quad screening hard to interpret with twins
  • FTS now includes serum analysis (September 2008)
    for twins

32
cardiac defect screening
  • An elevated NT has a 6X increased association
    with complex congenital heart disease (as opposed
    to 2-3 in the patient with a prior history) and
    therefore is a very important marker for disease
  • An abnormal NT in the presence of normal
    karyotype requires fetal echocardiography

33
pre-eclampsia and adverse prenatal outcomes
screening
  • PAPP-A and (uterine artery dopplers) at 11-14w to
    predict adverse outcomes (Faster Trial)
  • Odds ratios of PAPP-A lt 5th percentile
  • Intrauterine growth restriction 3.22
  • Birth weight at or below fifth percentile 2.81
  • Fetal loss before 24 weeks 2.50
  • Fetal or neonatal loss 2.15
  • Preterm birth at or before 32 weeks 2.10
  • Preterm birth at or before 37 weeks 1.87
  • Placental abruption 1.80
  • Premature preterm rupture of membranes 1.54
  • Preeclampsia 1.54
  • Gestational hypertension 1.47
  • If abnormal, increased surveillance to detect
    early oligohydramnios, IUGR, or hypertension is
    essential

34
The first problem with quality
  • Nuchal translucency training and quality
    assurance
  • Appropriate training of sonographers and
    adherence to standard technique for NT are
    essentials for good clinical practice.
  • success of a screening program necessitates
    system for regular audit continuous assessment of
    the quality of images.
  • Training is based on theoretical course
    practical instruction on how to obtain the
    appropriate image, make the correct measurement
    of NT, and presentation of a logbook of images.
  • Ongoing quality assurance is based on assessment
    of the distribution of fetal NT measurements and
    examination of a sample of images
  • Current standard Fetal Medicine Foundation (UK,
    Canada, USA) for initial accreditation, and
    yearly QA

35
The second problem with quality
  • Accredited NT is not meaningful by itself, and
    must be part of a screening program,
  • using software to adjust risks,
  • in concert with age,
  • laboratory, and
  • counselling

36
ACOG and SOGC
  • ACOG released similar guidelines in January 2007,
    and SOGC in February 2007
  • Basics
  • Triple screening is no longer good enough
  • Dont use age as a screening tool
  • Aim for highest DRs and lowest FPRs in any
    method
  • Consent and review all options
  • 2008 Minimum standard 75 DR, 5 FPR
  • Quality assurance important in FTS programs

37
ACOG and SOGC
  • Regardless of which screening tests you decide to
    offer your patients, information about the
    detection and false-positive rates, advantages,
    disadvantages, limitations, and risks and
    benefits of diagnostic procedures, should be
    available to patients so they can make informed
    decisions.
  • All women regardless of age should be offered and
    consented to screening for the most significant
    aneuploidies and a second trimester sonogram for
    dating, growth and anomalies
  • Amnio/CVS can be offered to women over age 40
    without screening, but screening should still be
    offered.

38
ACOG and SOGC
  • The practice of solely using maternal age of 35
    or older at the estimated date of delivery (EDD)
    to identify at-risk pregnancies should be
    abandoned

39
ACOG and SOGC
  • One size does not fit all
  • As long as the definitive diagnosis involves an
    invasive procedure which can cause miscarriage,
    there is simply no substitute to explaining all
    the options, their benefits, and risks
  • best screen is the one which will address the
    patients needs in terms of time of results and
    action depending on the results

40
Conclusions to take home
  • Adjust Risks
  • Dont use age alone anymore
  • Use age plus a high detection screening tool
  • Highest are
  • FTS with Nasal Bone (11-14w)
  • IPS (1st TM NT, PAPP-A Quad) (12w16-20w)
  • Any NT/NB must be performed by accredited
    facilities look for program based screening
  • Offer all options
  • Beware that screening isnt just aneuploidy, its
    much more

41
Screening is simple
11-13w6d
16-20w
hCG, AFP, uE3, Inhibin Quad 75-77
Quad PAPP-a SIPS 82-84
SIPS NT IPS 92-95
NTNBPAPP-ahCG FTS with Nasal Bone 92-95
17w to 20w
13w
42
Where?
  • Quad - all women (MSP)
  • SIPS - over age 38
  • IPS -
  • over age 40
  • Twins/Prior aneuploidy/HIV
  • Over age 35 with 3 prior miscarriages
  • Accredited NT SIPS, report sent to MD at 17-18w
    or later

43
Options (Non-MSP, accredited)
  • Pacific Centre for Reproductive Medicine
  • PacificFertility.ca
  • NTNBserum
  • Calgary Health Region
  • EarlyRiskAssessment.com
  • NTNBserum
  • Genesis Fertility Centre
  • Genesis-fertility.com
  • NT serum

44
Other Web Resources
  • www.mfmedicine.com
  • Fetal Medicine Canada
  • www.fetalmedicine.com
  • Fetal Medicine UK
  • Video from Prof Nicolaides
  • SOGC statement
  • http//www.sogc.org/guidelines/documents/187E-CPG-
    February2007.pdf

45
  • FMF reports 2008
  • Age
  • Weight
  • Ethnic
  • Parity
  • FHR
  • markers
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