Screening in pregnancy

Question 1

Which haematological conditions are screened for during pregnancy?

Answer 1

Anaemia: haemoglobin concentration is checked and if this is low iron, B12 and folate levels are checked to determine the cause

Haemoglobinopathies: checked for in specific groups e.g. African and Afro-Caribbean women at risk of sickle-cell disease or trait, screening varies according to local population groups

Blood-group and allo-antibodies (antigens other than Rh which are capable of causing haemolysis in the newborn e.g. Kell and Duffy)

Question 2

Which infections are screened for during pregnancy?

Answer 2

Asymptomatic bacteria: urine dip

HIV: blood test

HepB: blood test

Syphilis: blood test

Rubella: blood test

Question 3

Is group B strep screened for in the UK?

Answer 3

No

Question 4

If a woman is known to be group B strep positive what is given to reduce risk of transmission to the newborn?

Answer 4

Benzylpenicillin

Question 5

Discuss screening for Down’s syndrome

Answer 5

Screening is offered to all women as a combined test

Scan and blood test done at 11 - 13+6 weeks

Nuchal scan

Bloods: PAPP-A & hCG

Question 6

Results from the combined test that suggests baby has Down’s?

Answer 6

Thick nuchal translucency

Low concentration of PAPP-A

High concentration of bHCG

False+ rate = 3%

Question 7

Why is the combined test not an option after 14 weeks?

Answer 7

Nuchal translucency no longer visible

Question 8

What are the other causes of a thickened nuchal translucency?

Answer 8

Turner’s

Edward’s

Patau’s

Blocked lymphatic system

Cardiac failure

Congenital infections

Foetal anaemia

Question 9

At what nuchal translucency thickness would you investigate further?

Answer 9

>6mm

Question 10

What can be done if nuchal thickness cannot be measured or screening was missed?

Answer 10

Serum screening @ week 15-20 via triple or quadruple test

Question 11

What do the triple and quadruple tests measure?

Answer 11

Triple:

• a-fetoprotein
• Unconjugated oestradiol
• b-hCG

Quadruple:

• Triple + inhibin A

Question 12

Results of the triple and quadruple tests indicating Down’s

Answer 12

AFP: low

Unconjugated oestradiol: low

b-hCG: high

Inhibin A: high

Question 13

In which congenital anomaly are levels of alpha feto protein high?

Answer 13

Neural tube defects

Question 14

Results of the triple test in Edward’s syndrome?

Answer 14

AFP: low

Unconjugated oestradiol: low

b-hCG: low

Question 15

Consequences of a lower or higher chance result following Down’s screening?

Answer 15

Lower-chance result: shows that the chance of having a baby with Down’s syndrome, Edwards’ syndrome and Patau’s syndrome is lower than 1 in 150

> no further testing needed

Higher-chance result: shows that the chance of the baby having Down’s syndrome, Edwards’ syndrome or Patau’s syndrome is higher than 1 in 150 – that is, anywhere between 1 in 2 and 1 in 150 – this is called a higher-chance result

> offered amniocentesis or chorionic villus sampling

Question 16

Risk of amniocentesis/ chorionic villus sampling?

Answer 16

0.5-1% risk of miscarriage