Screening

Question 1

What is screening?

Answer 1

A process of identifying apparently healthy people who may be at increased risk of a disease or condition. They can then be offered information, further tests and appropriate treatment to reduce their risk and/or any complications arising from the disease or condition.”

Question 2

What are potential negative effects of screening?

Answer 2

Anxiety, stigma, false reassurance

Question 3

What is Wilson’s Criteria for any screening test?

Answer 3

1. Condition should be an important health problem
2. The natural history of the condition should be understood
3. There should be a recognisable latent or early symptomatic stage
4. There should be a test that is easy to perform and interpret, acceptable, accurate, reliable, sensitive and specific
5. There should be an accepted treatment recognised for the disease
6. Treatment should be more effective if started early
7. There should be a policy on who should be treated
8. Diagnosis and treatment should be cost-effective
9. Case-finding should be a continuous process

Question 4

What is screened for in antenatal period?

Answer 4

1. Infectious diseases (HIV, Hep B, Syphilis, Rubella)
2. Rhesus negative
3. Haemoglobinopathies (sickle cell, thalassaemia)
4. Foetal anomalies

Question 5

Who may also need to be screened?

Answer 5

The partner

Question 6

When does Rhesus disease occur?

Answer 6

1. Mother has RhD- blood
2. Baby in womb has RHD+ve blood –> Rh antigens can enter mother’s blood from baby during delivery
3. Mother responds to RhD+ve blood by producing antibodies
4. Mother becomes pregnant again with another RhD+ve foetus
5. Antibodies cross placenta and destroy foetal RBCs

Question 7

What are all RhD-ve women offered?

Answer 7

Anti-D injection at 28-30 weeks

It neutralises fetal Rh D + antigens which would have entered maternal blood and prevents creation of antibodies

Question 8

What is given if baby is RhD+ve after delivery?

Answer 8

Another injection of anti-D

Question 9

What scans are offered to check for foetal anomaly?

Answer 9

1. Down’s Syndrome screening

2. Anomaly scan

Question 10

What is the Down’s Syndrome screening?

Answer 10

• Opt-in
• Done in 1st trimester at dating scan

‘Combined screening’ consists of a nuchal translucency scan and blood test for:

1. hCG (Human chorionic gonadotrophin)
2. PAPP-A (pregnancy-associated plasma protein A)§

Question 11

How are results presented from Down’s screening?

Answer 11

Come as a ‘risk factor’ and cut-off is 1 in 150

2% of women will get ‘high risk result’

Detection rate should be 90%

Question 12

When result from Down’s screening is ‘high risk’, what are mothers offered?

Answer 12

Definitive pre-natal diagnosis

1. CVS from 11 weeks with risk of miscarriage of 1%
2. Amniocentesis from 15 weeks with risk of 0.8%

Question 13

What difficult situation can Down’s screening lead to?

Answer 13

Termination or not

Question 14

What is amniocentesis?

Answer 14

Removing and testing a small sample of cells from amniotic fluid

Question 15

What is CVS?

Answer 15

Chorionic villus sampling (CVS) is a test offered during pregnancy to check if your baby has a genetic or chromosomal condition

Question 16

What diseases are not routinely screened for?

Answer 16

1. Hep C
2. Chylamydia
3. Group B Strep (unless swab/urine tests are performed)

Question 17

When might Hep C screening be offered?

Answer 17

History of drug abuse of obstetric cholestacis

Question 18

What is obstetric cholestacis?

Answer 18

A disorder that affects your liver during pregnancy. This causes a build-up of bile acids in your body. The main symptom is itching of the skin but there is no skin rash