Ante- and Postnatal Screening Unit 2 Flashcards
Name the technique by which high frequency sounds are bounced off the fetus and converted to an image on a computer screen
Ultrasound imaging
Name two scans that are produced through ultrasound imaging
Dating scan and anomaly scan
When is a dating scan produced ?
8-14 weeks
What does a dating scan show ?
State of pregnancy and due date
When is an anomaly scan carried out ?
18-20 weeks
What does an anomaly scan show ?
Serious physical abnormalities in the fetus
Name a marker chemical that doctors check for the level of in a mother’s urine/blood
HCG hormone or AFP
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 ?
False positives and false negatives
If a fetus is wrongly diagnosed as having a condition when it doesn’t then this is what type of mistake ?
False positive
If a fetus is wrongly diagnosed as not having a confusion when is actual fact it does, then this is what type of mistake ?
False negative
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 ?
Screening test
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
Diagnostic test
Name two diagnostic tests
Amniocentesis and Chorionic Villus Sampling
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 ?
Karotype
When is amniocentesis carried out ?
14-16 weeks
Where are the cells taken from during amniocentesis ?
Amniotic sac
What is the negative aspect of amniocentesis?
Risk of miscarriage
When is CVS carried out ?
As early as 8 weeks
Where are the cells for CVS taken from ?
The chorionic villus of the placenta
What are the advantages of CVS over amniocentesis ?
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
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 ?
Pedigree chart/family tree
What does a line through a symbol on a pedigree chart show ?
That the person has died
Which symbol is used to represent a female ?
A circle
Which symbol is used to represent a male ?
A square
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) ?
Autosomal recessive inheritance
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
Autosomal dominant inheritance
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 ?
Autosomal incomplete dominance
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 ?
Sex-linked recessive inheritance
Name a condition whereby a baby is unable to change the amino acid Phenylalanine into tyrosine
Phenylketonuria
When is the test for phenylketonuria carried out on babies ?
A few days after birth
What name is given to the type of testing that occurs in babies after they are born ?
Postnatal screening
