Unit 2: Physiology & Health - Key Area 4: Antenatal and Postnatal Screening Flashcards
Why is antenatal care carried out?
To monitor the health of a pregnant woman and her developing foetus and baby.
What 3 things checked in a mother during pregnancy?
Blood pressure, blood type, blood and urine.
What can antenatal screening identify?
The risk of a disorder so that further (diagnostic) tests can be carried out if necessary, and a parental diagnosis can be given.
What are screening tests used for?
To detect signs and symptoms associated with a condition or disorder. This allows a degree of risk to be assessed but does not definitely confirm if the disorder is present.
What do screening tests require for more definite answers?
Diagnostic testing.
What is diagnostic testing?
Definite tests which establish, without doubt, wether a person is suffering from a specific condition or disorder.
What are the 3 types of antenatal screening?
Ultrasound, diagnostic testing, blood and urine tests.
What are the two types of ultrasound scans?
A dating scan and an anomaly scan.
How many ultrasound scans is a pregnant woman given during pregnancy.
A minimum of 2.
At what time of pregnancy is a dating scan carried out and what does this determine?
8-14 weeks. Determines the stage of pregnancy and due date which can be used with tests as marker chemicals which vary normally during pregnancy.
At what time of pregnancy are anomaly scans carried out and what for?
18-20 weeks. Detects serious physical problems/abnormalities in the foetus which allows parents to prepare/manage specialised birth/intrauterine therapy.
Why are routine blood and urine tests carried out throughout pregnancy?
Routine blood and urine tests are carried out throughout pregnancy to monitor the concentrations of marker chemicals which could indicate conditions like alpha fetoprotein e.g.
If a chemical in the blood is measured at he wrong time it could lead to a false positive. The atypical chemical concentration can lead to what further type of testing?
Diagnostic testing.
When are diagnostic tests carried out?
These tests are carried out if routine screening has indicated a risk of a condition, or for individuals already in high risk categories (e.g. woman over the age of 35), or if there is a family history of a harmful genetic disorder.
What are the 2 main procedures used in diagnostic testing?
Amniocentesis and chorionic villus sampling (CVS).
What is the process of amniocentesis?
Carried out at 14-18 weeks in the pregnancy where amniotic fluid is withdrawn which contains fetal cells. These are then examined under a microscope to obtain a karyotype for diagnosis.
What is the process of CVS?
Carried out between 9-14 weeks where a sample of placenta cells are taken from the fetal tissue. These cells are then cultured and used for karyotyping.
What are 3 differences between CVS and amniocentesis?
Amniocentesis: carried out at 14-18 weeks, tests fatal cells and uses needle and syringe through abdominal wall guided with ultrasound to extract.
CVS: carried out at 9-14 weeks, tests placenta cells and uses a needle through the stomach or a tubes, suction and force[s in the cervix.
What are risks of amniocentesis?
Miscarriage, infection, injury from the needle, inadequate results, rhesus disease and club foot.
What are the risks of CVS?
Miscarriage, infection, inadequate results and rhesus sensation.
Why are cells from CVS and amniocentesis cultured?
To obtain sufficient cells to produce a karyotype to diagnose a range of conditions.
What are one of the first parts of postnatal screening?
After the birth, the baby is give a blood test. The blood test involves taking a small blood sample by pricking the heel (heel prick test). The blood sample is tested for several rare conditions including phenylketonuria (PKU).
What is phenylketonuria?
Phenylketonuria is an autosomal recessive disorder, involving a substitution mutation to the gene coding for the enzyme which converts the amino acid phenylalanine to the amino acid tyrosine. Without the enzyme, phenylalanine accumulates in the blood and severely restricts the development of the brain.
Can phenylketonuria be treated?
If treatment is started soon after birth, it can result in normal brain development. This can be achieved through a strict diet where food high in phenylalanine are largely or completely eliminated from the diet.
Why can people with PKU still produce melanin?
They can consume tyrosine in their diet which complete the pathway to produce melanin.
What is the definition of haploid?
Only 23 chromosomes in a human cell (sex cells)
What is the definition of diploid?
46 chromosomes (2 sets) in a human cell (stomatic cell).