Screening in Pregnancy

Question 1

What is the equation for sensitivity?

Answer 1

true positive/ (positive + false negative)

Question 2

What is the equation for specificity?

Answer 2

true negative/ (negative + false positive)

Question 3

What are the two possible pathways in pregnancy?

Answer 3

green

red

Question 4

What is the green pathway?

Answer 4

midwife led

Question 5

What is the red pathway?

Answer 5

obstetrician led

Question 6

At what date does the booking visit + first dating scan happen?

Answer 6

10-13+6 weeks

Question 7

At what date does the follow up scan happen?

Answer 7

18-20 weeks

Question 8

What is the mother checked for at the first booking visit?

Answer 8

Take medical, surgical, drug, obstetric, family and social history to identify additional care needs.

Discuss mental health

Measure BP

Blood tests - FBC, blood group, rhesus status, check for infection [HIV, hepatitis C, B, syphilis) and haemoglobinapathies (thalasseamias, sickle cell disease).

Check immunity against chicken pox, rubella etc

Question 9

What is the baby checked for at the first booking visit?

Answer 9

Dating scan - Ultrasound scan to check for viability, determine gestation using fetal pole measurements, intrauterine pregnancy, number of pregnancies

Nuchal translucency

Question 10

What is Naegeles rule?

Answer 10

predicts an estimated due date based on last menstrual period then + 90 weeks and 7 days (280 days)

Question 11

What is screened for at the 20 week scan?

Answer 11

structural fetal anomalies (anomaly scan) such as cleft palate, heart anomalies, limb defects, CNS defects, renal abnormalities

Placental site position to aid in delivery

Question 12

What foetal anomalies are incompatible with life?

Answer 12

anencephaly

major heart defects

Question 13

If at the 20 week scan there is a low lying placenta, when should the mother be rescanned?

Answer 13

32 weeks

Question 14

What is a normal nuchal thickness at the booking scan?

Answer 14

<3.5mm

Question 15

What is done to screen for aneuploidy in those that have missed their first trimester screening?

Answer 15

screening option from 15-20+6 weeks

Amniocentesis and Chorionic Villus sampling

Question 16

What biochemical markers are screened for in the aneuploidy screening?

Answer 16

Alpha feto protein (AFP)
HCG
Unconjugated oestradiol
inhibin A

Question 17

How are HCG and AFP changed in downs syndrome?

Answer 17

reduced

Question 18

When is amniocentesis performed? What is its miscarriage rate?

Answer 18

15 weeks

1%

Question 19

When is chorionic villus sampling performed? What is its miscarriage rate?

Answer 19

12 weeks

2%

Question 20

When is sickle haemoglobin screened for?

Answer 20

booking scan

Question 21

What is the inheritance pattern of sickle haemoglobin?

Answer 21

autosomal recessive

Question 22

When is maternal anaemia screened for?

Answer 22

booking and 28 weeks

need to optimise Hb before birth to prevent haemorrhage

Question 23

When is Rhesus D screened for?

Answer 23

28 weeks

Question 24

When would the two dose of Rhesus D be given?

Answer 24

28 weeks and 34 weeks

Question 25

In what situation would Anti D-immunoglobulins be given to a mother within 72 hours?

Answer 25

``` delivery of a Rh +ve foetus termination of pregnancy miscarriage if gestation >12 weeks ectopic pregnancy if managed surgically antepartum haemorrhage abdominal trauma amniocentesis and CVS fetal blood sampling ```

Question 26

What is the test called that diagnoses a foetus' Rhesus status?

Answer 26

Coombs test

Question 27

How would a baby affected by Rhesus appear?

Answer 27

``` oedema jaundice anaemia heart failure kernicterus ```

Question 28

What is the pathogenesis behind Rhesus?

Answer 28

Rh +ve father and Rh-ve mother BUT Rh +ve baby Babies blood enters the mothers bloodstream and causes antibodies to be formed against the baby Rh antibodies attack the babies blood cells causing Rh disease

Question 29

What is the diagnostic criteria for gestational diabetes?

Answer 29

fasting glucose of >5.6mmol/litre OR | 2 hour plasma glucose of >7.8mmol/litre

Question 30

How is gestational diabetes diagnosed?

Answer 30

2 hour 75g oral glucose tolerance test (OGTT)