Ante- and Postnatal Screening Unit 2

Question 1

Name the technique by which high frequency sounds are bounced off the fetus and converted to an image on a computer screen

Answer 1

Ultrasound imaging

Question 2

Name two scans that are produced through ultrasound imaging

Answer 2

Dating scan and anomaly scan

Question 3

When is a dating scan produced ?

Answer 3

8-14 weeks

Question 4

What does a dating scan show ?

Answer 4

State of pregnancy and due date

Question 5

When is an anomaly scan carried out ?

Answer 5

18-20 weeks

Question 6

What does an anomaly scan show ?

Answer 6

Serious physical abnormalities in the fetus

Question 7

Name a marker chemical that doctors check for the level of in a mother’s urine/blood

Answer 7

HCG hormone or AFP

Question 8

If the levels of these marker chemicals are checked at an inappropriate point in the timeline and found to be high/low, this could lead to what types of false alarm ?

Answer 8

False positives and false negatives

Question 9

If a fetus is wrongly diagnosed as having a condition when it doesn’t then this is what type of mistake ?

Answer 9

False positive

Question 10

If a fetus is wrongly diagnosed as not having a confusion when is actual fact it does, then this is what type of mistake ?

Answer 10

False negative

Question 11

What name is given to the type of tests where they look at marker chemical levels and other indicators that look for signs and symptoms of a disorder, but does not tell definitively that the fetus has the disorder ?

Answer 11

Screening test

Question 12

What name is given to a definitive test that established without doubt that the fetus has a disorder? It is usually carried out following concerns after a screening test

Answer 12

Diagnostic test

Question 13

Name two diagnostic tests

Answer 13

Amniocentesis and Chorionic Villus Sampling

Question 14

Both diagnostic tests allow the collection of some of the baby’s cells and a photograph of the chromosomes all laid out. What name is given to the visual display of chromosome ?

Answer 14

Karotype

Question 15

When is amniocentesis carried out ?

Answer 15

14-16 weeks

Question 16

Where are the cells taken from during amniocentesis ?

Answer 16

Amniotic sac

Question 17

What is the negative aspect of amniocentesis?

Answer 17

Risk of miscarriage

Question 18

When is CVS carried out ?

Answer 18

As early as 8 weeks

Question 19

Where are the cells for CVS taken from ?

Answer 19

The chorionic villus of the placenta

Question 20

What are the advantages of CVS over amniocentesis ?

Answer 20

CVS carried out earlier in a pregnancy and if there is any problem, then a termination can be considered much earlier when it is less traumatic. I parents wait until 14-16 weeks as with amniocentesis, then it is much more traumatic

Question 21

What name is given to the charts used by genetic counsellors to assess the degree of risk in passing in a genetic disorder to children ?

Answer 21

Pedigree chart/family tree

Question 22

What does a line through a symbol on a pedigree chart show ?

Answer 22

That the person has died

Question 23

Which symbol is used to represent a female ?

Answer 23

A circle

Question 24

Which symbol is used to represent a male ?

Answer 24

A square

Question 25

What pattern of inheritance is shown when a condition carried in the autosomes has its genes relatively rarely expressed, skips generations and occurs more between members joined by a consanguineous marriage (too close in relation to each other) ?

Answer 25

Autosomal recessive inheritance

Question 26

What pattern of inheritance is shown when a condition carried in the autosomes appears every generation? Each person affected has a parent who suffered the condition and once the condition is lost from a branch of the tree it is lose altogether from the brand

Answer 26

Autosomal dominant inheritance

Question 27

What pattern of inheritance is shown when both alleles are expressed together and this is the most common phenotype, the number of males and females are affected in equal numbers ?

Answer 27

Autosomal incomplete dominance

Question 28

What pattern of inheritance is shown by a condition carried on the sex chromosomes, where many more males than females are affects and none of the affected males have sons with the trait ?

Answer 28

Sex-linked recessive inheritance

Question 29

Name a condition whereby a baby is unable to change the amino acid Phenylalanine into tyrosine

Answer 29

Phenylketonuria

Question 30

When is the test for phenylketonuria carried out on babies ?

Answer 30

A few days after birth

Question 31

What name is given to the type of testing that occurs in babies after they are born ?

Answer 31

Postnatal screening