Pre-Natal Testing

Question 1

What are the components of prenatal testing?

Answer 1

• prenatal screening

- prenatal diagnosis

Question 2

Contrast prenatal screening and prenatal diagnosis

Answer 2

• prenatal screening: focuses on finding problems among large population with affordable and non-invasive methods (eg. downs syndrome, blood borne viruses etc)
• prenatal diagnosis: focuses on pursuing additional detailed information once a problem has been found and can sometimes be more invasive (eg. chorionic villus sampling)

Question 3

What is the purpose of prenatal testing?

Answer 3

• enable timely medical/surgical treatment of a condition before or after birth
• give parents chance to terminate pregnancy with diagnosed condition
• give parents the chance to prepare physiologically, socially, financially, and medically for baby with health problem/disability/likelihoof stillborn
• organise fetal surveillance

Question 4

What are the types of screening during pregnancy?

Answer 4

• blood tests (FBC, blood group and rhesus state, haemoglobinopathies, infectious disease, chromosomal disorders)
• USS
• questionnaire

Question 5

Describe the first trimester combined test

Answer 5

Uses:

• maternal age
• nuchal translucency measurement
• free beta hCG and PAPP-A
• gestational age
• done from 11-14 weeks
• results show whether high or low chance of having a baby with Down’s Syndrome

Question 6

Describe the second trimester screening

Answer 6

Uses:

• maternal age
• biomarkers
• done 14-20 weeks
• not as good at detecting Down’s/Edward’s/Patau’s Syndrome

Question 7

What are the further options for women who have higher-chance result 1:150 from first or second trimester screening?

Answer 7

• no further tests
• more accurate blood screening NIPT
• diagnostic tests: chorionic villus sampling or amniocentesis

Question 8

Describe NIPT

Answer 8

• screening so not diagnostic
• from 10 weeks
• cell free DNA extracted and analysed from maternal blood test
• results given as low or high chance result
• if low chance then no further tests offered

Question 9

Describe chorionic villus sampling

Answer 9

• fine needle inserted through abdomen and into uterus or through cervix, and small piece of developing placenta removed
• done from 11 weeks
• tests for inherited disorders (eg. CF, sickle cell, thalassaemias, DMD)

Question 10

Describe amniocentesis

Answer 10

• needle inserted through abdomen and into amniotic fluid which is aspirated
• used for karyotyping if screening suggests aneuploidy
• from 15 weeks

Question 11

Describe ultrasound screening

Answer 11

• dating scan at 12 weeks for:
• number of pregnancies
• viability
• gestational weeks
• NT thickness
• NT defects
• anomaly scan at 20 weeks for:
• physical abnormalities (eg. spinda bifida, placental position)

Question 12

Describe preimplantation genetic diagnosis (PGD)

Answer 12

• offered to couples who risk passing on genetic disorder
• removal of 1 cell from early embryo
• uncommon and expensive

Question 13

What disorders is PGD acceptable for?

Answer 13

• a disorder that may affect capacity for live birth
• risk of child being born with or developing a serious disability
• eg. CF, fragile X syndrome, blood disorders etc.

Question 14

What are things to consider in the seriousness of a disability/disorder?

Answer 14

• views of those seeking treatment
• likely degree of suffering
• availability of effective treatment
• speed of degeneration
• extend of intellectual impairment
• family circumstances

Question 15

What is CRISPR gene editing?

Answer 15

• genetic engineering technique which involves genomes of living organisms are modified
• allows genomes to be edited in vivo with high precision, cheaply and with ease and can be used to make new medicines