Physiology and Health: Antenatal and Postnatal Screening Flashcards
A variety of techniques can be used to do what?
Monitor the health of the mother, developing fetus and baby
Antenatal and prenatal screening involves what?
Testing for diseases or conditions in a fetus or embryo before it is born
What does antenatal screening do?
Identifies the risk of a disorder so that further tests and a prenatal diagnosis can be offered
Common antenatal testing procedures include what?
Ultrasound scanning, amniocentesis and chorionic villus sampling (CVS)
What is an ultrasound scanner used for?
Producing an ultrasound image on a computer screen
Pregnant women are given two scans, what are they?
A dating scan and an anomaly scan
Dating scans do what and are used for what?
Determine pregnancy stage and due date.
Are used with tests for marker chemicals which vary normally during pregnancy.
When does a dating scan take place?
Between 8 and 14 weeks
Anomaly scans can detect what?
Physical abnormalities in the fetus
When does an anomaly scan take place?
Between 18 and 20 weeks
Routine blood and urine tests are carried out throughout pregnancy to monitor what?
The concentrations of marker chemicals
When are marker chemicals produced?
During normal physiological changes that take place during pregnancy
Measuring a chemical at the wrong time could lead to what?
A false positive result
An atypical chemical concentration can lead to what?
Diagnostic testing to determine if the fetus actually has s medical condition
What do diagnostic tests include?
Amniocentesis and chorionic villus sampling (CVS) from the placenta
Amniocentesis and CVS allow what?
A prenatal diagnosis to be made and can confirm the presence of conditions such as Down syndrome
Amniocentesis has a small risk of what?
Miscarriage
CVS can be carried out earlier in pregnancy than amniocentesis although it has what?
A higher risk of miscarriage
Cells from an amniocentesis sample or CVS can be cultured to obtain sufficient cells to produce what?
A karyotype to diagnose a range of conditions
A karyotype shows what?
An individual’s chromosomes arranged as homologous pairs
In deciding to proceed with these tests the element of risk will be assessed, as well as what?
The decisions the individuals concerned are likely to make if a test is positive
Family trees or pedigree charts are what and used to do what?
Are compiled.
Used to analyse patterns of inheritance in genetic screening and counselling.
Family trees are constructed to do what?
Provide information and advice in situations where there is the possibility of passing on a genetic disorder to potential offspring
Family trees can be used to analyse patterns of inheritance involving what?
Autosomal recessive, autosomal dominant, incomplete dominance and sex-linked recessive single gene disorders
Alleles are forms of the same gene what are the two types and describe them?
Homozygous - Individuals have two copies of the same allele.
Heterozygous - Individuals have copies of two different alleles.
Describe the autosomal recessive disorder, such as cystic fibrosis?
It is expressed rarely in the offspring, affects males and females equally and may skip generations
Describe the autosomal dominant disorder such as Huntington’s disease (HD)?
Shows up in every generation and affects males and females equally
Describe autosomal incomplete dominance?
The fully expressed form of the condition is rare, the partly expressed form is more common and males and females are affected equally
Describe sex-linked recessive disorders?
Males are affected more than females. Male offspring receive the condition from their mother; fathers cannot pass the condition on to their sons and female offspring can only be affected if the father has the condition and the mother is a carrier.
What does postnatal screening involve and why is it used?
Health checks that are carried out after the birth of the baby.
They are used for detecting certain conditions or abnormalities.
Postnatal diagnostic testing is used to do what?
Detect metabolic disorders such as phenylketonuria (PKU)
What is PKU?
An inborn error of metabolism caused by an autosomal recessive genetic disorder
In PKU a substitution mutation means what?
That the enzyme which converts phenylalanine to tyrosine is non-functional
If PKU is not detected soon after birth what happens?
The baby’s mental development can be affected
Individuals with a high level of phenylalanine are placed on what?
A restricted diet that lacks the amino acid phenylalanine
