Antenatal Screening Flashcards
how do you calculate sensitivity?
true positive/(all positive + false negative)
how do you calculate specificity?
true negative/(all negative + false positive)
when is the booking visit completed?
between 8-12 weeks gestation
what four things are done at the booking visit?
history
examination
blood tests
urinalysis
what three examinations are done during the booking visit?
height
weight
blood pressure
what bloods are done at the booking visit?
haemoglobin rhesus status syphilis HIV Hep B+C
when is the first ultrasound done?
8-12 weeks gestation
what does the first ultrasound scan look for?
viability
how many
estimate gestational age
structural anomalies
when is the most accurate time to establish the EDD?
8-12 weeks
what is EDD?
estimated date of delivery
what rule can be used to calculate EDD?
naegele’s rule
what is naegele’s rule?
add on nine months and seven days/280 days to the date of onset of a woman’s LMP = EDD
when is the foetal anomaly scan done?
20 weeks
what should be investigated in a history at the foetal anomaly scan?
physical/mental health of mother
foetal movements
what examinations should be done at the foetal anomaly scan?
BP urinalysis SFH lie + presentation foetal heart auscultation
what is SFH?
symphysis fundal height
what is placenta praevia?
when the placenta is low lying in the uterus and covers the cervix
if placenta praevia is seen at 20 weeks, when is another scan done?
32 weeks
what trisomy’s can be screened for?
21
18
13
what is trisomy 21?
downs syndrome
what is trisomy 18?
Edwards syndrome
what is trisomy 13?
patau’s syndrome
what secondary screening test is offered if there is a high risk result for a trisomy?
NIPT
how is trisomy screening performed in the first trimester?
measure nuchal thickness (NT)
combine this with HCG and PAPP-A for a full assessment
