Antenatal Care and Screening Flashcards
Why are there so many physiological changes in the body during pregnancy? What can these changes cause?
Physiological adaptation to pregnancy is essential as it allows the body to cope with the added strain. Many of these physiological changes can result in “minor ailments” of pregnancy. However it is also important to not mistake these for the worsening of pre-existing illness, which can sometimes be the case.
What is morning sickness? How many women are affected?
Morning sickness is the nausea and vomiting of early pregnancy (usually better by 16 weeks). It does not always occur in the morning though. The exact reasons for morning sickness are not clear. Around 80-85% of pregnant women experience morning sickness.
In which pregnancies are morning sickness worse? What can morning sickness progress towards? What can it progress to?
Morning sickness is worse in conditions where BetaHCG is increased (e.g. twin pregnancy). Can progress to hyperemesis gravidarum (more severe vomiting).
How does Cardiac output change in pregnancy? What other changes to the heart can be seen?
CO increases by 30-50%. HR also increases from 70-90bpm (By term the Blood flow to the heart must be about 1L/min). Palpitations become more common.
What happens to BP in the second trimester? Why? What happens in the third trimester?
BP drops in the second trimester. Due to expansion of the uteroplacentral circulation. Along with: - Fall in systemic vascular resistance. - Reduction in blood viscosity - Reduction in sensitivity to angiotensin. BP usually returns to normal in the third trimester.
What is pre-eclampsia?
A disorder of pregnancy characterized by the onset of high blood pressure and often a significant amount of protein in the urine. When it arises, the condition begins after 20 weeks of pregnancy.
What change is there to the output of urine in pregnant women?
GFR changes?
Urea/creatinine changes?
Bladder capacity changes?
There is increased urine output in pregnancy. - Renal plasma flow increases by 25-50% - GFR increases by 50% - Serum urea and creatinine decrease - Bladder capacity is reduced in pregnancy (in third trimester) due to pressure from the expanding uterus.
Why is there increase incidence of UTI among pregnant women? Why are UTIs especially important to treat in pregnant women.
- Increased urinary stasis. And decreased ability to fight off infection.
- Hydronephrosis is physiological in the third trimester and makes pyelonephritis more common Can be associated with preterm labour so important to treat.
Is anaemia common in pregnancy? And why?
Yes. During pregnancy your body produces more blood to support the fetus - if you do not get enough iron then mild anaemia is common.
Is it normal for haem to drop in pregnancy? How should we act?
Plasma volume increases by 50% and RBC mass by 25% - this results in haemoglobin drop by dilution from 133-121g/l.
Need to act on haem drop very quickly - give iron. Be aware that normal limits are different for pregnant people
What are respiratory changes in pregnancy?
- Progesterone acts centrally to reduce CO2: increased tidal volume, resp rate, plasma pH = SOB
- O2 consumption is increased 20%
- Hyperaemia of respiratory mucous membranes
GI changes in pregnancy?
- Oesophageal peristalsis is reduced
- Gastric emptying slows
- GORD, constipation
What would be the ideal scenario regarding pre-pregnancy councelling?
- All women would receive some pre-pregnancy counselling [in reality the majority of pregnancies are unplanned but pre-preg].
- Counselling is vital for women with any previous health or pregnancy problems
What are the main causes of maternal death?
- Cardiac
- Sepsis
- Thrombosis
- Neurological
What are some general health measures needed pre-pregnancy [for all women]?
General health issues: [these are actually often difficult to rectify]
- Improve diet
- Optimise BMI
- Reduce alcohol consumption
- Smoking cessation
Folic acid (400mcg) as it reduces neural tube defect risk
Confirm immunity to rubella
What are some known medical conditions that need to be discussed pre pregnancy?
- Pyschiatric health is very important [suicide is a common cause of maternal death]
- Stop/change any unsuitable drugs
- Advise regarding complications associated with maternal medical problems
- Advise against pregnancy in certain cases: aortic stenosis
What needs discussed regarding previous pregnancy problems in pre pregnancy counselling?
Maternally:
- C section
- DVT - Thromboprophylaxis reduces risk
- Pre-eclampsia - low dose aspirin reduces risk
Fetal
- Pre-term delivery: treat infection
- Intrauterine growth restriction: high dose folic acid
- Fetal abnormality: low dose aspirin
Why do carry out antenatal examinations?
- High quality antenatal care reduces fetal and maternal mortality
- Identifies abnormalities
What are some issues (mother, fetus, social) that can picked up from examination?
Fetus:
- Small for gestational age
- Fetal abnormality
Mother:
- Problems such as pre-exisiting or developing illness
- ‘minor’ problems of pregnancy such as anaemia
Social:
- Support
- Domestic violence
- Psychiatric Illness
What is included in a routine enquiry?
- Feeling well
- Feeling fetal movements
- Urinalysis is signs for protein, (UTIs, kidney infection)
- BP: to detect evolving hypertension
What is included in the abdominal palpation?
- Assess symphyseal fundal height (SFH)
- Estimate size of baby
- Estimate liquor volume
- How the baby lies - this is so that a breech position can be identified.
How can a breech position be rectified?
- Normally ECV (external cephalic version), this attempts to turn breech babies to normal position
- If this fails or is not opted then an elective caesarian section is normally carried out
What is antenatal screening and who is offered it?
- Testing of a symptomless population in order to detect cases of a disease at an early stage
- Women are offered screening but this is not compulsory [counselling prior to screening is important]
What infections are we screening for? And how are these infections rectified?
Hep B
- If infected can provide passive and active immunisation for baby
Syphillis
- Easily treated with Penicillin
HIV
- Maternal treatment and careful planning reduces vertical transmission
Iron Deficienct anaemia
- Screened by routine blood tests, treated with iron tablets
Isoimmunisation
- [development of antibodies against blood groups]
- If a Rhesus negative women is carrying a rhesus positive baby she will develop anti D antibodies if the fetal red blood cells enter the maternal circulation
- Screening allows us to provide them with passive immunisation to destroy fetal RBCs in the maternal circulation
What is the aim of the first scan?
- Ensure pregnancy viable
- Multiple pregnancy
- Identify abnormalities incompatible with life
- Offer and carry out Down’s syndrome screening
What is the role of a detailed anomaly scan?
- Systematic structural review of baby
- Not possible to identify all problems
- Can identify problems that need intrauterine or postnatal treatment
What are increased risks for down syndrome?
- Usual cut off for ‘high risk’ reporting is 1 in 150
- Maternal age
- 1in 1667 risk at age 20yrs
- 1 in 30 risk at age 45yrs
- Personal or family history of chromosomal abnormality
Explain the screening process for Down’s syndrome.
- Multiple screening tests are available
- Parents must be aware prior to any screening taking place that tests for fetal abnormality only provide a risk of their baby being affected
- Further testing will be offered to definitively tell if a baby is affected
What can the 1st trimester screening detect? When is it carried out?
10-14 weeks gestation
- Detects 60% fetuses with T21 for a false positive rate of 5%
- Detects 85-90% fetuses with T21 for a false positive rate of 5%
What are the dimensions for nuchal translucency? What does it show?
Measurements are taken between Crown Rump Length’s of 45-84mm.
Increases with gestational age and the incidence of chromosomal and other abnormalities is related to the size, rather than the appearance of NT.
If there is a high risk result relating to NT what are the next steps?
Further testing is offered if risk of Down’s syndrome is >1 in 150
Options:
- CVS
- Amniocentesis
- Non-invasive Prenatal testing
What is CVS?
Chorionic villus sampling (CVS) is a test carried out during pregnancy to detect specific abnormalities in an unborn baby. A sample of cells is taken from the placenta (the organ that links the mother’s blood supply with her unborn baby’s) and tested for genetic defects.
When is CVS carried out and what are the risks?
Between 10-14 weeks
1-2% risk of miscarriage
What is amniocentesis? When is it carried out and what are the risks?
It involves removing and testing a small sample of cells from the amniotic fluid – the fluid that surrounds the unborn baby in the womb (uterus).
- Carried out 15 wks onwards
- ~1% risk of miscarriage
Explain the use of non-invasive prenatal testing.
- [Currently only available privately]
- Maternal blood taken
- Can detect fetal cell free DNA
- Can look for chromosomal trisomies
- If high risk result then patient still recommended to have invasive testing to confirm
Who is offered screening for neural tube defect?
What are the screening options available?
- People who have personal or family history of NTD (they will be advised to take 5mg Folic acid to reduce risk)
- First trimester ultrasound to detect anencephaly and sometimes spina bifida (variants of NTD)
- Second trimester biochemical screening
- Carried out if not able to get NT measurement
- Maternal serum is tested for alpha fetoprotein
- >2.0MoM is high risk and warrants investigation
- Second trimester (20wk) ultrasound will detect >90% of NTD
What are we looking for in terms of NTD on ultrasound?
Pinched in skull at front.
What is the purpose of 2nd trimester ultrasound?
- Purpose of detecting fetal abnormality
- 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
