Antenatal Screening Flashcards
Organisation of a low risk pregnancy?
All care = midwive delivered US appointment at 8-12 weeks Review: 16 weeks Anomaly scan: 20 weeks (US) Seen again: week 25,28,31,34,36 If no delivery seen at: week 38,40,41,42
Organisation of high risk pregnancy?
Care led by consultant obstetrician
Appointment schedule is determined case to case
8-12 week scan with midwife looks at?
Full history
Height, weight, BP
Blood tests
Types of blood tests at 8-12 week booking scan with midwife?
Hb ABO Rhesus status and AB Syphilis HIV Hep B and C
When is most accurate time to confirm viability, gestational age and delivery date estimate?
Secondary appointment for US
Crown rump length (CRL) does estimated delivery date and gestational age
What if estimated gestational age is not done at weeks 8-12?
It is then estimated using head circumference which is less accurate
What is used prior to US to predict EDD?
Naegele’s rule
- Based on onset of woman’s LMP add on 9 months 7 days to get due date
11 main conditions looked for in 20 week anomaly scan?
- Anencephaly
- Open spina bifida
- Cleft lip
- Diaphragmatic hernia
- Gastrochisis
- Exomphalos
- Serious cardiac abnormalities
- Bilateral renal agenesis
- Lethal skeletal dysplasia
- Edward’s syndrome
- Patau’s syndrome
What is T18?
Edward’s syndrome
What is T13?
Patau’s
Trisomy risk assessment in 1st trimester involves what?
Measuring nuchal translucency
Combined with HCG and PAPP-A blood test to given a risk level that the baby has down’s
What can be screening for in 2nd trimster?
Only T21 not T18/13
What is NIPT?
Non-invasive prenatal testing
-This detects fetal DNA fragments in a sample of blood taken from mother and is more accurate than combined test so can be offered to women identified as high risk from combined test (although can’t offer TOP based on this result as only screening test)
What is done as diagnostic testing for trisomy and when?
Amniocentesis after 15 weeks
Miscarriage rate <1%
Chorionic villus sampling after 12 weeks
Miscarriage rate <2%
What deficiencies scanned for at booking scan?
Iron anaemia
Folate
B12
When should blood group and antibody status be determined in pregnancy?
At boking and 28 weeks to prevent fetal anaemia
What can help prevent D antibodies forming in Rh -ve women and when?
Anti D injections
Routinely given at 28 weeks and after any sensitizing event
Sensitizing events may include?
TOP Antepartum haemorrhage Invasive procedures External cephalic version Fall or accident
What is given after birth of a baby who is Rh +ve?
Anti-D
What tests is used to see if there is fetal blood in maternal circulation?
Kleihauer Betke test
Can tell if sensitizing event has happened
What measurement is recomended at each antenatal appointment from 24 weeks?
Serial measurement of symphysis fundal height (SFH)
What is placenta praevia?
When placenta is low lying in the uterus and covers all or part of the cervix
Site identified by anomaly scan
If placenta has been low at anomaly scan?
Site is checked at 32 weeks gestation by US
What are al of the different appointmnets?
Booking
20w
28w
20 week scan looks for?
Cleft Heart NTD Limb defects Placental site Diaphragmic hernia
28w scan looks for?
RC antibodies
Anaemia
What do you measure in 1st trimester for trisomy screening?
Skin thickness behind foetal neck using US (Nuchal thickness NT)
What is a normal NT?
<3.5mm should be considered normal when CRL is between 45 and 84mm
What is NIPT?
Non-invasive prenatal testing
What does NIPT detect?
Fetal DNA fragments in sample of blood from mother
CffDNA detectable when?
From around 10 weeks f pregnancy and amount of detectable DNA thought to rise as pregnancy continues
CffDNA stands for?
Cell free fetal DNA testing
CffDNA is more or less dangerous than other testing?
Less
Doesn’t carry risk of miscarriage and can give parents to be higher quality ifo
