antenatal testing

Question 1

screening timeline

What does T13, T18 and T21 using ultrasound test do?

Answer 1

Tells you if a baby is growing normally

Question 2

screening timeline

when is the glucose tolerance test done

Answer 2

done in first 4 weeks of pregnancy

Question 3

screening timeline

Overview the tests carried out in the antenatal phase of pregnancy

Answer 3

Initially:
- blood tests for sickle cell and thalassaemia

• later blood tests for T21, T18, T13

Question 4

vaccinations

What are the 5 infections that Pregnant women need to be vaccinated against (TORCHes)

think TORCHes

Answer 4

1. Toxoplasmosis
2. Others (syphilis, hep B)
3. Rubella
4. Cytomegalovirus (CMV)
5. Herpes Simplex/HIV

Question 5

downs syndrome

What is down’s syndrome

Answer 5

Congenital disorder due to trisomy (extra copy) of chromosome 21

Question 6

downs syndrome

Why is screening needed for the large, low risk population

Answer 6

90% of pregnancies occur in women under 35

Question 7

testing for downs syndrome

Why is amniocentesis not suitable for mass screening and what is used instead

for first part think risk and time

Answer 7

• Amniocentesis is too risky and time consuming for mass screening
• Combined test is used instead

Question 8

testing for downs syndrome

What is the combined test

think 2 types of markers and age

Answer 8

Combination of ultrasound markers and biochemical markers with maternal age.

Question 9

testing for downs syndrome

what are the biochemical and ultrasound markers used in the combined test

think type of serum levels and plasma protein-A and BhCG for biochemical

for ultrasound think a type of translucency

Answer 9

Biochemical markers:
- maternal serum levels of pregnancy associated with plasma protein-A (PAPP-A) serum and free BhCG

Ultrasound markers:
- nuchal translucency

Question 10

diagnostic tests

What are diagnostic tests for downs and turners syndrome

Answer 10

• Amniocentesis
• Chrionic Villus sampling (CVS)

Question 11

diagnostic tests - amnio vs CVS

What is amniocentesis, in what weeks of pregnancy can it be done, how accurate is it in detecting major autosomal trisomies, how are results received and how long does it take and what are these trisomies

Answer 11

• Fluid removed by ultrasound guided needle inserted into uterus
• can be done between weeks 12-34
• 90-100% accurate
• results by qPCR within 24h

Trisomies:
- trisomy 21: Down’s
- trisomy 18: Edwards
- Trisomy 13: Patau

Question 12

diagnostic tests - amnio vs CVS

what is chorionic villus sampling, what weeks of pregnancy can it be done and when are results received

Answer 12

• chorionic villi sample is removed from developing placenta
• can be done in weeks 11-14
• results received in 3 days

Question 13

antenatal screening

Why is antenatal screening in the 1st trimester an advantage?

think:

• timing of information
• invasive procedures
• detection of things
• dating pregnancy

Answer 13

• Information earlier so more options for parents
• Reduced number of invasive procedures
• May detect other anomalies/risk of anomaly at time of scan
• Can date pregnancy accurately

Question 14

haemolytic disease of the Newborn

What is a Haemolytic Disease of the Newborn

for step 1, think red blood cells being attacked

for step 2, think why antibodies are produced

for step 3, think what is administered if rh blood group is rh negative

Answer 14

1. Red blood cells of the fetus/newborn are attacked by maternally derived antibodies
2. Maternal antibodies produced as a direct result of a blood group incompatibility between mother and fetus with ans directed against the Rhesus (Rh) antigen on fetal erythrocytes
3. If blood group is Rh negative, an injection of anti-D immunoglobulin is administered to prevent you from developing antibodies against your baby’s blood cells in future pregnancies