Antenatal care & screening tests in pregnancy Flashcards
How many weeks are the: first, second and third trimester? [3]
1st trimester: 0-12 weeks
2nd trimester: 13-26 weeks
3rd trimester: 27-50
How can you work out gestational age? [1]
Use Naegele’s rule (LMP + 1 year + 7 days) – 3 months
Antenatal care pathway depends on number and course of previous pregnancies, medical history
and patients’ choice.
When would the following be chosen as the level of care? [2]
What does each involve? [1]
Midwifery-led care
Obstetrician-led care
Midwifery-led care:
- for uncomplicated pregnancies.
- It involves 10 appointments for nulliparous women and 7 for multiparous.
Obstetrician-led care:
- If women are classed as higher risk, including multiple pregnancy, maternal health problems.
- It consists of all the midwifery appointments PLUS extra scans and/or joint clinics to cover maternal medical conditions including mental health
Describe what occurs in the < 10 weeks ‘booking clinic’?
Booking visit
* general information e.g. diet, alcohol, smoking, folic acid, vitamin D, antenatal classes
* BP
* urine dipstick
* check BMI
Booking bloods/urine
* FBC, blood group, rhesus status, red cell alloantibodies, haemoglobinopathies
* hepatitis B, syphilis
* HIV test is offered to all women
* urine culture to detect asymptomatic bacteriuria
* Screening for thalassaemia (all women) and sickle cell disease (women at higher risk)
At the ‘booking clinic’ a risk-assessment is performed. What is the based off a patients’ history?
PMH:
- Diabetes
- Hypertension
Previous obstetric history:
- previous still birth
Demographic characteristics:
- High BMI
- Black ethnicity
Test results:
- Rh-ve
If a ptx had previous pre-eclampsia, what medication would they be given and when? [1]
What scans would they have and when? [1]
previous pre-eclampsia: start aspirin at 12 weeks
- serial growth scans at 28, 32 and 36 weeks.
Non –white ethnicity have a higher risk for gestational diabetes.
What is the screening test and when would it occur? [2[
Book screening by OGTT between 24-28 weeks
Which screening tests are performed at the booking test and what are they screening for?
Blood group & Rh D status:
- Rhesus D mothers will be offered a blood sample to establish fetal genotype from DNA.
- If fetus predicted to be Rhesus +, Anti-D will be administered in the 3rd trimester and if any significant bleeding
Full blood count:
- Screening for anaemia
Screening for hemoglobinopathies (Hb electrophoresis):
- Screening for thalassemia (allwomen)
- Screening for sickle cell (onlyhigh-riskwomen)
- If women are carrier, also partners are tested .If both partners are carriers, prenatal diagnosis can be offered
Sexual health and ID:
- HIV, Hep B and Syphilus
When does screening for DS occur? [1]
11-14 weeks
Describe the process of screening for DM
The combined test is the first line and the most accurate screening test. It is performed between 11 and 14 weeks gestation and involves combining results from ultrasound and maternal blood tests:
Ultrasound measures nuchal translucency, which is the thickness of the back of the neck of the fetus.
- Down’s syndrome is one cause of a nuchal thickness greater than 6mm.
Blood tests
* Beta‑human chorionic gonadotrophin (beta-HCG) – a higher result indicates a greater risk
* Pregnancy‑associated plasma protein‑A (PAPPA) – a lower result indicates a greater risk
State which tests exists for screening for DS and when they occur [+]
11-14 weeks: Combined test
- Nuchal translucency (US): > 6mm
- Maternal blood tests (bHCG - high; PAPPA - low)
14-20 weeks: Triple test:
- bHCG - higher indicates greater risk
- AFP - lower result indicates greater risk
- Serum oestriol - lower result indicates greater risk
14-20 weeks: Quadruple test
- bHCG - higher indicates greater risk
- AFP - lower result indicates greater risk
- Serum oestriol - lower result indicates greater risk
- Inhibin-A: - higher indicates greater risk
Antenatal Testing for Down’s Syndrome
- The screening tests provide a risk score for the fetus having Down’s syndrome.
- When the risk of Down’s is greater than [] in [], the woman is offered [2]
Antenatal Testing for Down’s Syndrome
The screening tests provide a risk score for the fetus having Down’s syndrome.** When the risk of Down’s is greater than 1 in 150** (occurs in around 5% of tested women), the woman is offered amniocentesis or chorionic villus sampling.
Describe what amniocentesis or chorionic villus sampling involve when testing for DS? [2]
Chorionic villus sampling (CVS)
- involves an ultrasound-guided biopsy of the placental tissue. This is used when testing is done earlier in pregnancy (before 15 weeks).
Amniocentesis
- involves ultrasound-guided aspiration of amniotic fluid using a needle and syringe.
- This is used later in pregnancy once there is enough amniotic fluid to make it safer to take a sample.
Describe what is meant by Non-invasive prenatal testing (NIPT) [1]
It involves a simple blood test from the mother. The blood will contain fragments of DNA, some of which will come from the placental tissue and represent the fetal DNA
- These fragments can be analysed to detect conditions such as Down’s
- NIPT is not a definitive test, but it does give a very good indication of whether the fetus is affected.
NIPT is gradually being rolled out in the NHS as an alternative to invasive testing (CVS and amniocentesis) for women that have a higher than 1 in 150 risk of Down’s syndrome.
What are the Edward’s syndrome quadraple tests like? [4]
When does screening for gestational diabetes occur? [1]
Who is given screening? [2]
What would be a positive result? [1]
the oral glucose tolerance test (OGTT) is the test of choice
* women who’ve previously had gestational diabetes: OGTT should be performed as soon as possible after booking and at 24-28 weeks if the first test is normal
* women with any of the other risk factors should be offered an OGTT at 24-28 weeks
gestational diabetes is diagnosed if either:
* fasting glucose is >= 5.6 mmol/L
* 2-hour glucose is >= 7.8 mmol/L
How do you measure SFH? [1]
- Feel for top of the fundus
- Feel for upper border of the
symphysis pubis - Place measuring tape on uterine
fundus and with cm marks facing down, measure to the previously noted symphysis pubis - Turn tape over and read measurement
What is appropriate growth of fetus - using fundal height landmarks for 12, 20, 36 and 37-40 weeks?
When do you test for abnormal breech presentations? [1]
How do you do this? [3]
Abdominal palpitation & confirm with USS @ 36 weeks
Delivery options are:
- external cephalic version
- breech vaginal delivery
- c-section
How do you specifically measure date a pregnancy? [1]
date the pregnancy measuring the crown-rump
length
What does is this US investigating? [1]
The nuchal translucency (NT)
