Antenatal Care and Screening

Question 1

what is the purpose of antenatal screening?

Answer 1

allows conditions to be detected early in a symptomless population to be treated for mother/baby

Question 2

describe screening for anomalies by US

first visit scan and detailed anomaly scan

Answer 2

First scan visit:
- ensure pregnancy is viable
- multiple pregnancy
- identify abnormalities incompatible with life
- offer and carry out Down’s syndrome creening

Detailed anomaly scan:
- systematic structural review of baby
- not possible to identify all problems
- can identify problems that need intrauterine or postnatal treatment

Question 3

nuchal translucency measurements are taken between Crown Rumps Length’s of?

Answer 3

Question 4

what specific measurements does a screening test involve?

describe screening for trisomy 13, 18 and 21

Answer 4

• nuchal translucency (NT) measurement
• CRL
• blood test for PAPP-A (pregnancy associated plasma protein-A), hCG (human chorionic gonadotrophin)
• maternal age
• If not able to get NT measurement or pregnancy is over this gestation, a second trimester screening test can be done between 14+2 and 20+0 : Alpha-fetoprotein, Oestriol, hCG and inhibin-A

Question 5

what happens when a screening test gives a high risk result?

Answer 5

• further testing is offered if risk of a trisomy is > 1 in 50
• options: CVS, amniocentesis, non-invasive prenatal testing

Question 6

describe the purpose of a second trimester ultrasound

Answer 6

• performed with the purpose of detecting fetal abnormality
• a good screening test for major structural abnormalities but a poor test for chromosomal abnormalities as:
  50% of fetuses with T21 will have a normal detailed USS
  17% of fetuses with T18 will have a normal detailed USS
  9% of fetuses with T13 will have a normal detailed USS

Question 7

what does antenatal examination involve?

Answer 7

• routine enquiry: feeling well? feeling fetal movements? (after 20 weeks)
• blood pressure: detect evolving hypertension
• urinalysis
• abdominal palpation: assess symphyseal fundal height (SFH), size of baby, liquour volume, determine fetal presentation e.g. breech or vertex
• listen to foetal heart
• estimate foetal growth