Antenatal Care and Screening

Question 1

what % of women does morning sickness affect?

Answer 1

80-85%

Question 2

in what conditions can morning sickness be worse?

Answer 2

where HCG is higher e.g. twins and molar pregnancy

Question 3

by how much does CO increase in pregnancy?

Answer 3

30-50%

Question 4

why does BP drop in the 2nd trimester?

Answer 4

expansion of the uteroplacental circulation

fall in systemic vascular resistance, blood viscosity and sensitivity to angiotensin

Question 5

by how much does renal plasma flow increase in pregnancy?

Answer 5

20-25%

Question 6

by how much does GFR increase in pregnancy?

Answer 6

50%

Question 7

why are UTIs and pyelonephritis more common in pregnancy?

Answer 7

increased urinary stasis

physiological hydronephrosis

Question 8

by how much does plasma volvume increase in pregnancy?

Answer 8

50%

Question 9

by how much does RBC mass increase in pregnancy

Answer 9

25%

Question 10

why does platelet count fall in pregnancy?

Answer 10

dilution

Question 11

progesterone acts centrally to reduce CO2 which results in? in pregnancy

Answer 11

increased TV
increased RR
increased plasma pH

Question 12

why is GI motility reduced in pregnancy?

Answer 12

increased progesterone and decreased motillin

Question 13

components of pre-pregnancy counselling

Answer 13

general health measure (diet, BMI, alcohol), smoking cessation advice, folic acid 400mcg, confirm immunity to rubella. Known problems
• Optimise maternal health
• Psychiatric health is important
• Stop/change any unsuitable drugs
• Advice regarding complications associated with maternal medical problems
• Occasionally advise against pregnancy (diabetes or epilepsy)

Question 14

previous pregnancy problems: maternal

Answer 14

counsel regardind risk of recurrence of same problems
Csection
DVT
pre-eclampsia
actions to reduce risk of recurrence include: thromboprophylaxis and low dose aspirin

Question 15

previous pregnancy problems: foetal

Answer 15

risk of recurrence
pre term delivery
IUGR
foetal abnormality
actions to reduce:
treatment of infections, high dose folc acid

Question 16

components of antenatal exam

Answer 16

routine enquiry
BP
urinalysis
abdo palpation
determine foetal presentation
listen to foetal heart

Question 17

discuss antenatal screening

Answer 17

All women are offered screening, but it is not compulsory. Appropriate counselling prior to screening is important. Screening allows conditions to be detected early in a symptomless population to be treated for mother/baby. Infections screened for are hepatitis B, syphilis, HIV and MSSU. If infected with hep B it is possible to provide passive and active immunisation for baby. Syphilis can be treated with penicillin. Maternal treatment and careful planning reduced vertical transmission of HIV. Iron deficiency anaemia is also screened for. Isoimmunisation, Rhesus status and anti-c, anti-kell.

Question 18

screening for anomalies by USS: first visit scan

Answer 18

o Ensure pregnancy viable
o Multiple pregnancy
o Identify abnormalities incompatible with life
o Offer and carry out Down’s syndrome screening

Question 19

screening for anomalies by USS: detailed anomaly scan

Answer 19

o Systematic structural review of baby
o Not possible to identify all problems
o Can identify problems that need intrauterine or post-natal treatment

Question 20

discuss the screening for down syndrome

Answer 20

Down Syndrome is a chromosomal abnormality characterised by trisomy 21. The overall risk is 1 in
700. Usual cut off for “high risk’ reporting is 1 in 150. At age 20 the risk of having a baby with down
syndrome is 1 in 1667 but increases to 1 in 30 by age 45. Likelihood increases if there is a personal or
family history of chromosomal abnormalities.
There are multiple screening tests available for Down’s Syndrome, but women and their partners must
be aware prior to any screening takes place that the can only provide a risk of their baby being
affected. Further testing will be offered to definitively tell if a baby is affected. Embarking on prenatal
screening sometimes results in parents having to make a difficult decision regarding termination of
pregnancy.

Question 21

first trimester screening: when

Answer 21

10-14 weeks

Question 22

first trimester screening: what?

Answer 22

maternal risk factors
serum bHCG
pregnancy associated plasma protein A (PAPP-A)
foetal nucal translucency

Question 23

describe non-invasive prenatal testing

Answer 23

To perform non-invasive prenatal testing a sample of maternal blood needs to be taken. In this sample it is possible to detect foetal cell free DNA. This can be examined to look for chromosomal abnormalities. It is not offered on the NHS. If high risk, it is still recommended to have invasive testing to confirm.

Question 24

describe the screening for NTD

Answer 24

Screening for neural tube defects is not routinely offered since the introduction of first trimester screening. If there is a personal or family history of NTD they are at higher risk and should be advised to take 5mg folic acid to reduce risk. The first trimester ultrasound can detect anencephaly and sometimes spina bifida, both variants of NTD. Second trimester biochemical screening is carried out if it was not possible to get an NT measurement. Maternal serum is tested for alpha fetoprotein. >2.0MoM is high risk and warrants investigation. The 20-week scan will detect > 90% of NTD

Question 25

discuss second trimester USS

Answer 25

This scan is performed with the purpose of detecting foetal abnormality. This is a good screening test for major structural abnormalities but a poor test for chromosomal abnormalities: 50% with T21, 17% with T18 and 9% with T13 will have a normal detailed USS.