Antenatal Care and Screening Flashcards
how do you asses robustness of screening
sensitivity
specificity
how do you calculate sensitivity
true positive/positive +false negative
how do you calculate sensitivity
true negative/negative + false positive
what is the sensitivity for first trimester Down’s syndrome screening
90%
false positive - 5%
so 1/20 women who are high risk will have a baby thats not effected
what history is taken in the firs antenatal appointment
PMH Past obsectric history Past surgical history medications allergies social histories family history mental health (screened at every appointment) FGM
how do you asses gestation before first scan
add nine months and 7 days onto onset of last period
what investigations are done at the booking visit
Hb ABO, rhesus Syphilis, HIV, hep B&C Urinalysis, MSSU, C&S Ultrasound
scan
- confirm vitality
- multiple pregnancies
- estimate gestational age
- detect major structural abnormalities that may be identified
- offer Down syndrome screening
what is done at follow up visits ( 3)
History
- physical and mental health
- fetal movements
examination:
- BP and urinalysis
- Symphysis - fundal height
- lie and presentation
- engagement of presenting part
- fetal heart auscultation
why is ultrasound screening done
Reduction in perinatal mortality and morbidity
Potential for in utero treatment
Identification of conditions amenable to neonatal surgery
what foetal abnormalities are checked for at a 20 week scan
Anencephaly Open spina bifida Cleft lip Diaphragmatic hernia Gastroschisis Exomphalos Serious cardiac abnormalities Bilateral renal agenesis Lethal skeletal dysplasia Edward's syndrome (trisomy 18) Parau's syndrome (trisomony 13)
what is placenta praaevia
placenta is low lying in the womb and covers all or part of the entrance (cervix)
what increases risk of Down syndrome
increased maternal age
1/100 when 40
what is the first trimester down’s risk assessment
Nuchal translucency
HCG and PAPP-A
Value of <3.6 is normal when the crown rump length is between 45 and 84mm
what is second trimester Down syndrome screening
Blood sample at 15-20 weeks
Assay of HCG and AFP
less accurate
what is considered high risk for downs
> 1:250 is high risk and needs amniocentesis (optional)
what is the risk of baby having Down syndrome is nuchal translucency is >3.5
1/20
higher the NT the higher the risk
what biological markers are used for second trimester screening
Alpha fetoprotein
Human chorionic gonadotrophin
Unconjugated estradiol
Inhibit A
what is diagnostic testing for Down’s syndrome
Amniocentesis
- after 15 weeks
- miscarriage rate of 1%
Chorionic villus sampling
- performed after 12 weeks
- miscardage rate of 2%
what is amniocentesis
thin needle into amniotic sac
what is chorionic villus sampling
biopsy of the placenta
what major haemoglobin disorders are screened for in pregnancy
HbS (sickle cell anaemia)
Thalassemias
both are autosomal recessive
need screened for
50% risk of carrier
25% change of being effected
25% of not being affected at all
why is maternal anaemia an issue
65% increase in risk in pregnancy
can cause foetal anaemia
causes by:
- iron deficiency
- folate deficiency
- B12 deficiency
- screened at 28 weeks
- optimise Hb prior to birth
what do you give a Rh - mother if her baby is Rh+
Anti-D antibody
how do you pick up foetal anaemia
ultrasound doppler
if >32 weeks they get C section
if <32 weeks they get a foetal blood transfusion
what are the risk factors for gestational diabetes
BMI >30
Previous macrocosmic baby weight 4.5 to above
Previous gestational diabetes
Family history of diabetes
Minority ethnic family origin with high prevalence of diabetes
how do you measure foetal growth
symphysis fundal height measured at each antenatal appointment from 24 weeks of pregnancy
plotted on a customised charge
what should you advise women who are at high risk of pre-eclampsia to take
75mg of aspirin daily from 12 weeks until the birth of the baby
what makes women at high risk of pre-eclampsia
hypertensive disease in previous pregnancy
chronic kidney disease
autoimmune disease eg. lupus or antiphospholipis
type 1 or type 2 diabetes
chronic hypertension
what makes a women at moderate risk of pre-eclampsia
first pregnancy >40 y/o pregnancy at interval of more than 10 years BMI of 35 or more family history of pre-eclampsia multiple pregnancy
what is screened for via urinalysis
UTI
Asymptomatic bacteria
PET
Diabetes