U2 KA4 - Antenatal And Postnatal Screening

Question 1

Describe the two types of Ultrasounds

Answer 1

Dating Scans
*An ultrasound image carried out at 8-14 weeks
* Determine stage of pregnancy and due date
* Used with biochemical tests for marker chemicals

**Anomaly scan **
*An ultrasound image carried out at 18-20 weeks ​It is used to check for presence of serious *physical abnormalities in the foetus ​
*Major organs are checked

Question 2

Describe the Biochemical tests for pregnant women

Answer 2

Types of tests
*Blood pressure ​
*Blood and urine tests

Biochemical tests MUST be used in conjunction with a Dating scan as marker chemical levels change during pregnancy. ​

Question 3

Purpose of Antenatal screening

Answer 3

Antenatal screening identifies the risk of a disorder so that further tests and a prenatal
diagnosis can be offered.

Question 4

What is diagnostic testing and when is it offered?

Answer 4

A definitive test that produces results that establish without doubt a whether a person is or is not suffering from a specific condition ​

They can be offered to a pregnant women if​

*There is evidence of a potential problem emerged from screening tests​
*History of genetic disorders in her family ​
*Is known to belong to a high risk group (aged 40+)​

Question 5

What are the Two Types Of Diagnostic Tests?

Answer 5

• Amniocentesis
• Chorionic villus sampling (CVS)

Question 6

Describe Amniocentesis

Answer 6

*Involves the withdrawal of amniotic fluid containing foetal cells ​
*These cells are cultured and examined under a microscope​
*The full chromosome complement is arranged to form a karyotype​
*It allows chromosomal abnormalities to be detected

Question 7

Describe Chorionic villus sampling

Answer 7

Involves taking a tiny sample of placental cells by using a fine tube inserted into the mother’s reproductive tract​

These cells are cultured and used for karyotyping

Question 8

Discuss the differences between Amniocentesis and CVS

Answer 8

CVS is gives faster results (8-10 weeks)
CVS only takes 20 minutes
CVS has immediate Karyotyping

Amniocentesis has a very small risk of infection
Amniocentesis smaller miscarriage rete (0.5%)

Results not 100% reliable for either

Question 9

Diagnostic test for PKU?

Answer 9

The test for PKU involves a blood test to check for the presence of excess phenylalanine (an amino acid) in the blood

Question 10

PKU Treatment

Answer 10

If they are found to suffer from PKU they are placed on a restricted diet containing the minimum quantity of phenylalanine required for normal growth

Question 11

Describe Autosomal recessive inheritancetraits

Answer 11

*The trait is expressed relatively rare​
*The trait may skip generations​
*Males and females affected in equal number​

Question 12

Describe Autosomal dominant inheritancetraits

Answer 12

*The trait appears in every generation​
*Each suffer has affected parent​
*When branches of tree not express trait, trait fails to reappear in future​
*Males and females affected in equal number

Question 13

Describe Autosomal incomplete dominance inheritancetraits

Answer 13

*The fully expressed form of the disorder occurs relatively rarely ​
*The partly expressed form occurs much more frequently ​
*Each sufferer of the fully expressed form has two paretnts who suffer the partly expressed form ​
*Males and females are affected in equal numbers