Antenatal and postnatal screening
No description yet. This curated deck is ready for daily study.
Card preview (17)
What is the purpose of the dating scan?
Determines stage of pregnancy and the due date
How many ultrasound scans do pregnant women receive and at what stage of pregnancy are they performed?
Two: Dating scan - 8-14 weeks Anomaly scan - 18-20 weeks
what is the purpose of the anomaly scan?
Checks for serious physical abnormalities
Why is timing important when deciding when to do biochemical tests on a pregnant women?
Could result in false positive or false negative results if tests are done at a stage in pregnancy where the level of that biochemical marker would be high/ low anyway
What is a screening test?
detects signs and symptoms associated with a condition assesses probability of the individual having a condition NOT A DEFINITIVE TEST
What is a diagnostic test?
A definitive test used to establish whether a person has a specific condition or not
In what scenarios may a pregnant woman be offered a certain diagnostic test?
• evidence of potential abnormality from a screening test • family history of genetic condition • women is over 35
Examples of diagnostic tests?
• Amniocentesis • Chorionic villus sampling
Explain the process of amniocentesis
-withdrawal of amniotic fluid containing fetal cells • cells are cultured in order to produce a karyotype which allows for the diagnosis of multiple genetic conditions
what is a karyotype?
• A visual display of a persons chromosome complement • Allows for the diagnosis of genetic disorders
When in a pregnancy is amniocentesis usually performed?
weeks 14-16
Explain the process of chorionic villus sampling
• A tube is inserted into the female reproductive tract in order to sample placental cells • These cells are cultured to produce a karyotype
what are the advantages/ disadvantages of amniocentesis and chorionic villus sampling?
• chorionic villus sampling can be carried out earlier in pregnancy (as early as 8 weeks) compared to amniocentesis, therefore termination of pregnancy can be carried out earlier • CVS is a more invasive procedure than amniocentesis with higher likelihood of miscarriage due to the procedure
Explain what causes PKU
a substitution mutation means that the enzyme which converts phenylalanine to tyrosine is non functional A build up of phenylalanine can result in mental impairment
How do people with PKU manage their condition?
diet low in phenylalanine
How is PKU detected in newborns?
Blood tests are done on newborn babies to identify excess phenylalanine