Antenatal Care and Screening Flashcards
In normal antenatal management, the initial booking appointment should be carried out ideally by when?
10 weeks
At the booking visit, a thorough history should be taken, specifically touching on what things?
Medical history, menstrual history, any past obstetric history, family and social history, as well as psychiatric history if not mentioned in medical
At the booking visit, what should you check with regards to psychiatric history?
If there are any present or past psychiatric conditions. Also ask about mood to screen for depression.
What examinations of the woman should be performed at the booking visit?
Height and weight to calculate BMI, blood pressure, cardio exam and also abdominal exam
The fundus of a pregnant uterus is usually palpable by when for a singleton pregnancy?
12 weeks
Explain Naegele’s rule to calculate estimated due date?
This predicts the estimated due date based on the woman’s last period. Add on 9 months and 7 days (280 days) from the first day of the last period to arrive at the due date.
What defines a baby born at term? What percentage of babies are born within this time?
37-42 weeks / 90%
What percentage of babies are born on their due date? What percentage are born a week either way of this date?
4% / 60%
What investigations relating to blood are screened for at a booking appointment?
Hb for anaemia / blood group, rhesus status and atypical antibody screen to identify Rh- women
What infections are screened for via blood tests at the booking appointment?
HIV, syphilis, Hep B/C
At a booking appointment, it is important to test (via a blood test) a woman’s immunity status to what?
Rubella
If HIV testing is refused at booking appointment, when can it be offered again?
28 weeks
Urinalysis is always done at a booking appointment. What type of sample should be taken? What is this to check for?
Mid-stream sample of urine / culture and sensitivity for UTI or asymptomatic bacteriuria, also checking for proteinuria for pre-eclampsia and also for diabetes
At the booking appointment, a follow-up ultrasound should be organised for roughly when in the pregnancy?
11-14 weeks
The initial ultrasound is used to do what 5 things?
Confirm viability of pregnancy / confirm singleton or multiple pregnancy / estimate gestational age / detect any major structural abnormalities / Down’s screening if requested
What factor on ultrasound is used to estimate gestational age if a) < 13 weeks? b) 13+ weeks?
a) Crown-rump length b) head circumference
What things should always be asked about in a history at every antenatal appointment?
Physical and mental health, foetal movements
What examinations/investigations should be done at every antenatal appointment? What is this screening for?
BP and urinalysis for proteinuria to screen for pre-eclampsia
What examination is done at every antenatal appointment from 24 weeks onwards? What is this for?
Symphysial-fundal height, to assess for normal foetal growth
When is the anomaly scan performed? What is this used for?
18 - 20+6 weeks / used to screen for foetal structural abnormalities e.g. cardiac abnormalities, neural tube defects to reduce perinatal morbidity/mortality and pick up conditions amenable to neonatal surgery
How good is the anomaly scan at picking up Down’s syndrome?
50% of babies with DS will have a normal anomaly scan
Major structural abnormalities occur in what percent of pregnancies? These usually occur in who? Because of this, the NHS foetal anomaly screening programme guidelines state what?
2-3%, mainly in low-risk women. It states that all pregnant women should be offered an anomaly scan at 18-20+6 weeks by a midwife or clinician at first contact or booking appointment
NICE recommends that all women should be offered a screening test for what condition as part of their routine antenatal care?
Down’s syndrome
What should occur before Down’s syndrome screening?
Couples should be given time to make a decision about whether they want the screening or not. They should be counselled to think about how a positive result would affect their management of the pregnancy - if they would not consider termination they may choose not to have the screening at all
What aspect of the combined test for Down’s syndrome should be performed first? When should this be done? What things must be clarified here?
Ultrasound scan, at 11-14 weeks. This is used to establish gestation and also to measure nuchal translucency
What is a normal crown rump length between 11-14 weeks?
45-80mm
Why can combined testing for Down’s syndrome not be done beyond 14 weeks?
Because the nuchal translucency is no longer visible after this point
What things are checked in a blood test for combined testing for Down’s syndrome?
PAPP-A and beta hCG
What would be the expected values of PAPP-A, beta hCG and nuchal translucency if a baby was positive for Down’s syndrome?
PAPP-A = decreased / beta hCG = increased / nuchal translucency = increased (> 3.5 for a CRL between 45-80mm)
Describe the sensitivity and false positive rate for combined testing for Down’s syndrome?
90% sensitivity with a false positive rate of 5% (i.e. will pick up 90% of babies with Down’s but 1/20 of the women given a positive result will actually have an unaffected baby)
If nuchal thickness cannot be measured, or a woman presents for Down’s syndrome screening later than 14 weeks, what is done?
A blood sample is taken at 15-20 weeks for an assay of beta hCG, AFP, inhibin A and unconjugated oestriol
What would be the expected values of beta hCG, AFP, inhibin A and unconjugated oestriol in Down’s syndrome?
beta hCG = increased / AFP = decreased / inhibin A = high / unconjugated oestriol = decreased
For Down’s screening in both first and second trimester, the results are combined with what other factors to give a personalised risk?
Gestation and maternal age
Describe the sensitivity and false positive rate for second trimester screening for Down’s syndrome?
70-75% sensitivity for a 5% false positive rate (i.e. will pick up 70-75% of babies with Down’s but 1/20 of the women given a positive result will actually have an unaffected baby)
A risk of what following Down’s syndrome screening indicates the need for further investigation?
A risk greater than 1/250
If a baby is at high risk of Down’s syndrome and the pregnancy is beyond 15 weeks gestation, what is the next best test to do? What is the miscarriage rate?
Amniocentesis - 1%
If a baby is at high risk of Down’s syndrome and the pregnancy is between 12 and 15 weeks gestation, what is the next best test to do? What is the miscarriage rate?
Chorionic villus sampling - 2%
When is foetal DNA detectable in maternal blood to perform NIPT? Why is NIPT a better test for foetal aneuploidy?
7 weeks, and increases as the pregnancy continues. Better test because it is more accurate and does not carry any risk of miscarriage
What placental disorder is screened for in routine antenatal care?
Placenta praevia
What finding on the anomaly scan would make you suspicious of placenta praevia? What would you do if this was the case?
The placenta lying over the cervix - arrange another abdominal scan at 32 weeks
If an abdominal scan for placenta praevia was still abnormal at 32 weeks, what is the next step in management?
Vaginal scan
What are the two haemoglobinopathies that can be screened for in pregnancy? When is this screening done?
Sickle cell anaemia and thalassemia - can be tested for up to 10 weeks
What specific deficiencies are checked for in an anaemia screen in pregnancy? When is this done?
Iron deficiency, folate deficiency, B12 deficiency. Checked for at booking and again at 28 weeks.
A haemoglobin level of less than what suggests iron supplements may be necessary? Why is it important to optimise haemoglobin levels in pregnancy?
< 11g/100ml / to minimise bleeding risk at birth
All women should have their blood group and antibody status checked when in pregnancy?
At booking and at 28 weeks
If a woman is Rhesus -, at what two antenatal care appointments should they be given doses of anti-D?
28 and 34 weeks
What questions should be asked regarding mental health at every antenatal appointment?
Do you have new feelings or thoughts which you have never had before that make you feel disturbed or anxious? Are you experiencing thoughts of suicide or harming yourself? Are you feeling incompetent as a mother, or as though you can’t cope? Are you feeling estranged or distant from your baby? Are these feelings persistent?
How and when is screening for gestational diabetes carried out?
Screening is carried out via the oral glucose tolerance test (2 hour 75g) in high risk women at 24-28 weeks
At the booking appointment, any risk factors for gestational diabetes should be established. What are these?
BMI > 30, previous macrosomic baby weighing 4.5+kg, previous gestational diabetes, Fx of diabetes in first degree relatives
Gestational diabetes can be diagnosed if a woman has either a) a fasting plasma glucose of what? b) a 2 hour plasma glucose level of what?
a) 5.1mmol + b) 8.5mmol +
What are the two key determinants of assessing foetal growth?
Foetal movements and symphysial fundal height
Serial measurements of symphyseal fundal height are recommended at each antenatal appointment from when? Why?
24 weeks - improves the prediction of a SGA foetus
Women with a single symphysial fundal height measurement below the 10th centile on an individualised population chart or serial measurements which suggest slow or static growth should receive what investigation next?
Ultrasound measurement of foetal size
What are some examples of women in whom symphysial fundal height measurements will be inaccurate? How should the growth of their babies be measured instead?
High BMI, large fibroids, hydramnios - use serial US assessment of foetal size
At 20 weeks, the uterus should be at the level of which structure? At 36 weeks, the uterus should be at the level of which structure?
Umbilicus / xiphisternum
In terms of foetal wellbeing, if a change in foetal movements is reported, what are the next steps in management?
Prompt assessment with cardiotocography +/- ultrasound
Any woman with one high risk factor or more than 1 moderate risk factor for pre-eclampsia should be advised to take what medication?
Aspirin 75mg daily from 12 weeks until delivery
What are some high risk factors for pre-eclampsia?
Hypertension during a previous pregnancy, CKD, autoimmune disease, diabetes, chronic hypertension
What are some moderate risk factors for pre-eclampsia?
First pregnancy, aged 40+, pregnancy interval of > 10 years, overweight, Fx, multiple pregnancy
What is done for the first time at the 36 week antenatal assessment?
Assessment of the position of the baby
If at 36 weeks a baby is found to be in breech position, what can be offered?
External cephalic version
If a woman presents for antenatal assessment at 41 weeks, what can be done?
Offer membrane sweep or induction of labour
What supplements should be advised in pregnancy?
Folic acid pre-conception until 12 weeks, usually 0.4mg but 5mg if high risk and also 10 micrograms of vitamin D daily
What are some factors increasing risk of neural tube defects?
Obesity, previous child with NTD, the mother or father has NTD, epilepsy, pre-existing diabetes, malabsorption e.g. IBD
Pregnant women should be advised not to eat which foods?
Unpasteurised milk, blue cheese, pate, any raw or undercooked meat, liver products
