Antenatal care and screening Flashcards
Objectives of antenatal (pre-birth) care?
Detect and manage pre existing maternal disorders that may affect pregnancy outcome
Prevent or detect and manage maternal complications of pregnancy
Prevent or detect and manage foetal complications of pregnancy
Detect congenital foetal problems if requested by parents
Plan with the mother the circumstances of birth to ensure maximum safety for the mother and baby and the maximum parental satisfaction
Promote health and safety for both mum & baby
Provide advice regarding lifestyle
Offer reproductive choice
Principles of screening in antenatal care?
Any screening test should be:
highly sensitive
highly specific
have a high positive predictive value
easily used in a large population
safe and cheap
quick and straightforward to perform
able to detect a disease with a known natural history and where early diagnosis has a proven benefit
When a patient visits, what should be taken from their history?
Obstetric
Medical & Surgical
Medications
Allergies
Mental heath
Family
Social
What should be examined when patient comes for booking visit?
Height
Weight
Blood pressure
Blood tests that are taken on booking visit?
Hb (haemoglobin)
ABO; Rhesus status and antibodies
Syphilis; HIV; Hep B&C;
Urinalysis
Use of ultrasound on booking visit?
confirm viability
Singleton/multiple pregnancy chorionicity
Estimate gestational age – most accurate time /method to establish EDD (estimated delivery date)
Detect major structural anomalies that may be identified in early pregnancy
Offer Trisomy Screening
What is Placenta praevia?
when the placenta is low lying in the uterus and covers all or part of the cervix. Its site is identified at the anomaly scan
In most women, as the womb enlarges, the placenta migrates out of the way. True/false?
True
If the placenta has been ’low’ at anomaly scan the site is rechecked at 32 weeks gestation by ultrasound.
Sometimes a transvaginal scan is required for placental site
For trisomy screening, what conditions can be checked?
Down’s syndrome T21
Edward’s Syndrome T18
Patau’s Syndrome T13
Can choose to be tested for all three or just DSS or T13 &18 or all three in first trimester
Trisomy risk assessment in first trimester?
Measure of skin thickness behind fetal neck using ultrasound (Nuchal thickness; NT)
Measured at 11-13+6 weeks
Combined with HCG and PAPP-A
A value of < 3.5 mm would be considered normal when the CRL (coronal rump length) is between 45 and 84mm.
Trisomy assessment factors?
Requires accurate pregnancy dating
Requires detailed counselling
‘Low risk’ does not exclude a trisomy
‘High risk’ does not mean foetus affected by a trisomy
Why is second trimester screening for T21 carried out in some cases and what does it involve?
For those women who miss first trimester screening
For those women in whom 1st trimester screening is unsuccessful
Uses a combination of Maternal Age + Biochemical Markers to assess risk. Biochemical markers include:
Alpha-fetoprotein (AFP)
human Chorionic Gonadotrophin (hCG)
unconjugated oestradiol (UE3)
inhibin A
If a woman undergoes the earlier screening for T21, with the current screening design the mid-trimester biochemical screen should not also be offered. true/false?
True
What is NIPT and when is it offered?
NIFT (Non-Invasive Prenatal Testing) if high chance result for any trisomy as a secondary SCREENING test
How can NIPT detect cases of trisomy?
detects foetal DNA fragments in a sample of blood taken from the mother
What is another name for NIPT?
Cell free fetal DNA (cffDNA) testing is also known as Non-Invasive Prenatal Testing (NIPT)
From what point is NIPT detectable in pregnancy?
detectable from around 10 weeks of pregnancy and the amount of detectable DNA is thought to rise as the pregnancy continues
CffDNA (NIPT) tests are more accurate than the combined test and studies have shown that it correctly identifies more cases of Down’s syndrome in pregnancy. true/false?
True
Why is improved accuracy important in cffDNA/NIPT?
The improved accuracy is important as cffDNA itself does not carry any risk of miscarriage and can give parents-to-be higher quality information about their baby’s risk of Down’s syndrome
Why is NIPT preferred over combined testing?
Its improved accuracy compared to the combined test does mean that fewer women will go on to have the invasive diagnostic test when their baby does not in fact have Down’s syndrome
Apart from NIPT, what are the more invasive tests?
Amniocentesis:
Usually performed after 15 weeks
Carries a miscarriage rate of <1%
Chorionic villus sampling:
Usually performed after 12 weeks
Carries a miscarriage rate of <2%
What is the women deficient in for maternal anaemia?
Iron deficiency
Folate deficiency
B12 deficiency
When is maternal anaemia checked?
Screened at booking at 28 weeks
Aim of maternal anaemia treatment in pregnant woman?
Aim to optimise Hb prior to birth
Why are blood groups and red cell antibodies important in screening?
- If transfusion needed- needs matched for antibodies
- Some red cell antibodies can cause fetal anaemia- a treatable & identifiable condition
- Anti D injections can be given to prevent D antigens forming in Rh negative women- given routinely at 28 w and after any sensitizing event i.e. falls, road traffic accident etc. Given again after birth if baby Rh +ve (cord blood tested)
Mental health questions to ask patient during antenatal care?
Do you have new feelings and thoughts which you have never had before, which make you disturbed or anxious?
Are you experiencing thoughts of suicide or harming yourself in violent ways?
Are you feeling incompetent as a mother, as though you can’t cope, or feeling distanced or estranged from your baby?
Are these feelings persistent?
Do you feel you are getting worse?
At booking appointment, assess the risk factors for gestational diabetes. What are the risk factors for gestational diabetes?
- BMI above 30kg/m2
- previous macrosomic baby weighing 4.5kg or above
- previous gestational diabetes
- family history of diabetes (first‑degree relative with diabetes)
- minority ethnic family origin with a high prevalence of diabetes
Offer women with any one of these risk factors testing for gestational diabetes
What is the need for serial measurement of symphysis fundal height (SFH)?
recommended at each antenatal appointment from 24 weeks of pregnancy as this improves prediction of a SGA (small for gestational age) neonate
What is SFH?
Symphysis fundal height (SFH) is a measurement of the size of the uterus during pregnancy.
It is the distance from the pubic bone to the top of the womb (uterus).
It is used to detect foetal intrauterine growth restriction (IUGR), which is a condition where the foetus does not grow as expected.
SFH is measured using a tape after 24 weeks’ gestation
What conditions/circumstances can result in an inaccurate SFH reading?
BMI > 35
large fibroids
hydramnios (excessive accumulation of amniotic fluid in the uterus during pregnancy)
What is pre-eclampsia?
a complication of pregnancy that causes high blood pressure, proteinuria, or other signs of organ damage
What factors put women at high risk of pre-eclampsia?
hypertensive disease during a previous pregnancy
chronic kidney disease
autoimmune disease such as systemic lupus erythematosus or antiphospholipid syndrome
type 1 or type 2 diabetes
chronic hypertension
Advice for women at high risk of pre-eclampsia?
women at high risk of pre-eclampsia to take 150mg of aspirin daily from 12weeks until 36 weeks
What factors put women at moderate risk of pre-eclampsia?
first pregnancy
age 40years or older
pregnancy interval of more than 10years
body mass index (BMI) of 35kg/m2or more at first visit
family history of pre-eclampsia
multiple pregnancy
Advice for women at moderate risk of pre-eclampsia?
women with more than one moderate risk factor for pre-eclampsia to take 150mg of aspirin daily from 12weeks until the birth of the baby
What is checked for using urinalysis during antenatal screening?
UTI
Asymptomatic bacteriuria
Diabetes
What is screened at 28 weeks gestation?
Red cell antibodies
Anaemia
What is screened at 20 weeks gestation?
Anomaly scan - cleft, heart, NTD (neural tube defects), limb defects, placental site, diaphragmic hernia, abdominal wall defects, lungs abnormalities, brain abnormalities, urinary tract abnormalities
What is screened throughout antenatal care period?
- BP
- Urine (UTI, PET, diabetes)
- Macrosomnia/IUGR (intra-uterine growth restriction)
- Mental health
- Abuse and support
What is Naegele’s rule?
Predicts an estimated due date based on the onset of the women’s last menstrual period
Add 9 months and 7 days to arrive at the due date (280 days)
Pregnancy begins from first day of last period so around 2-3 weeks after conception
