Antenatal Care and Screening Flashcards
what % of women does morning sickness affect?
80-85%
in what conditions can morning sickness be worse?
where HCG is higher e.g. twins and molar pregnancy
by how much does CO increase in pregnancy?
30-50%
why does BP drop in the 2nd trimester?
expansion of the uteroplacental circulation
fall in systemic vascular resistance, blood viscosity and sensitivity to angiotensin
by how much does renal plasma flow increase in pregnancy?
20-25%
by how much does GFR increase in pregnancy?
50%
why are UTIs and pyelonephritis more common in pregnancy?
increased urinary stasis
physiological hydronephrosis
by how much does plasma volvume increase in pregnancy?
50%
by how much does RBC mass increase in pregnancy
25%
why does platelet count fall in pregnancy?
dilution
progesterone acts centrally to reduce CO2 which results in? in pregnancy
increased TV
increased RR
increased plasma pH
why is GI motility reduced in pregnancy?
increased progesterone and decreased motillin
components of pre-pregnancy counselling
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)
previous pregnancy problems: maternal
counsel regardind risk of recurrence of same problems
Csection
DVT
pre-eclampsia
actions to reduce risk of recurrence include: thromboprophylaxis and low dose aspirin
previous pregnancy problems: foetal
risk of recurrence pre term delivery IUGR foetal abnormality actions to reduce: treatment of infections, high dose folc acid
components of antenatal exam
routine enquiry BP urinalysis abdo palpation determine foetal presentation listen to foetal heart
discuss antenatal screening
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.
screening for anomalies by USS: first visit scan
o Ensure pregnancy viable
o Multiple pregnancy
o Identify abnormalities incompatible with life
o Offer and carry out Down’s syndrome screening
screening for anomalies by USS: detailed anomaly scan
o Systematic structural review of baby
o Not possible to identify all problems
o Can identify problems that need intrauterine or post-natal treatment
discuss the screening for down syndrome
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.
first trimester screening: when
10-14 weeks
first trimester screening: what?
maternal risk factors
serum bHCG
pregnancy associated plasma protein A (PAPP-A)
foetal nucal translucency
describe non-invasive prenatal testing
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.
describe the screening for NTD
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
discuss second trimester USS
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.
