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)
