what are Qualities of a good counsellor
what are Clinical signs of down syndrome
they are at risk of leukaemia and alzhemiers when older
what are other features of Down syndrome
name screening tests for Down syndrome
Ultrasound
Maternal serum screening
non-invasive parinatal screening(NIPS/NIPT)
WHEN Can you use each of the screening tools for Down syndrome
Ultrasound in first trimester: nuchal translucency scan 11-13weeks. Increased NT
detects 75% T21 cases.
- Maternal serum screening: 15-18 weeks, triple test (AFP, BhCG, oestradiol), 60%
T21
- Ultrasound in second trimester: 18-23 weeks, FA scan
- Non-invasive perinatal screening (NIPS/NIPT): >10 weeks, cell free DNA in
maternal blood, most accurate for T21
what are the SCREENING tests for Down syndrome
Ultrasound in first trimester: nuchal translucency scan 11-13weeks. Increased NT
detects 75% T21 cases.
- Maternal serum screening: 15-18 weeks, triple test (AFP, BhCG, oestradiol), 60%
T21
- Ultrasound in second trimester: 18-23 weeks, FA scan
- Non-invasive perinatal screening (NIPS/NIPT): >10 weeks, cell free DNA in
maternal blood, most accurate for T21
what can you look at for diagnosing Down syndrome
karyotype and QF-PCR
Why a couple might battle to decide whether to have testing done or not
Which medications are contraindicated in pregnancy
Roaccutane
Warfarin
Carbamazepine
what are teratogenic factors
o Medications - Drug categories
o Contraindicated
Roaccutane
Warfarin
Carbamazepine
o Infections
TORCH
o Maternal illness
Uncontrolled diabetes
what happens in FDA category C
Risk cannot be ruled out, potential benefits may justify potential risk
what happens in FDA category A
no risk is shown in the drug
what happens in FDA category X
the drug is contraindicated in pregnancy
what are indications for genetic counselling
Prenatal risk for Down syndrome: AMA or other screening
Ultrasound identified abnormalities
Family History of genetic condition – e.g. cystic fibrosis
Previous abnormality – e.g. child with Down syndrome
Exposure to teratogens
o Medications - Drug categories
o Contraindicated
Roaccutane
Warfarin
Carbamazepine
o Infections
TORCH
o Maternal illness
Uncontrolled diabetes
Consanguinity
Increased risk of recessive conditions
what is the deal with advanced maternal age and which age group is that
women above the age of 35
o The risk of chromosomal abnormalities of a fetus increases with increasing age of the
mother.
o Older women have a greater chance of underlying disease that may increase the risk
of congenital abnormalities in their offspring, e.g. Diabetes Mellitus
Ultrasound in second trimester - Fetal anomaly (FA) scan (18 to 23 weeks
o Soft markers, e.g.
o Echogenic bowel
o Short femur
o Short humerus
o Nuchal fold more than 6mm
o Hypoplastic nasal bone
o Hydronephrosis
o Major abnormalities e.g.
cardiac defects
Neural tube defects
Maternal serum screening
o 15-18 weeks
o “triple test”- AFP, BhCG, Oestradiol
o T21 - 60% <35 / 75-90% >35 T18 - 60 –75%)
o 4 in 1 test- adds dimeric inhibin A (increases detection +- 10%)
o Increased AFP – useful in detection of open NTD’s
o Not offered in the state system
Ultrasound in first trimester
o Nuchal Translucency scan:
o 11 – 13 weeks
o Increased NT - Detects up to 75% Down syndrome
o Combined with and BhCG PAPP-A (85% )
o Combined with presence/absence of nasal bone (95%)
o New U/S markers being added
o (5% false +)
o Major abnormalities (e.g. anencephaly)
SCREENING TESTS VS DIAGNOSTIC TESTS
Screening tests are non-invasive and are used for prenatal screening. Only give us an
indication as to how likely it is that the fetus has a specific condition. Screening tests can
identify cases that may benefit from diagnostic testing. Diagnostic tests can provide a clear
diagnosis, but are associated with a risk of miscarriage.
DIAGNOSTIC TESTS
Foetal karyotype obtained by:
o Chorionic villus sampling (CVS)
11-13 weeks
1-2% risk of miscarriage
Results: 2-3 weeks
o Amniocentesis
16-20 weeks
1 in 500 risk of miscarriage
Results: 72 hours or 3 weeks depending on test
o Cordocentesis
After 20 weeks
2% risk of miscarriage
Results: 3 days
Karyotype
o Results takes 2 to 3 weeks
o Cells are cultured
o Full karyotype
o Provide information on numerical and structural abnormalities of all chromosomes
o Indicated when multiple abnormalities are detected on ultrasound
QF-PCR
o Result within 72 hours
o No culture required
o Also only give info about possible trisomy 13,18, 21 and sex chromosomes
o Can’t distinguish between trisomy and translocations
o Indicated when one of the above trisomies are suspected
FISH (Fluorescent In Situ Hybridization)
o can be requested for quick result (2-3 days)
o Will only give info about possible trisomy 13,18, 21 and sex chromosomes.
o Not full karyotype
o Indicated when one of the above trisomies are suspected
TOP ACT - CHOICE ON TERMINATION OF PREGNANCY ACT, 1996 (ACT NO. 92, 1996.)