Blood Tests & Screenings Flashcards
What is the aim of screening?
aims to identify people who are at risk of having a particular disease or medical condition before they show any sign of having it
Why does it mean when you are divided into low and high chance groups?
high risk groups will be offered further tests to find out if they have a particular condition or not
Explain ‘the sieve’
Everyone taking the test, some get caught in the sieve and referred for further tests. Low risk people get sieved through.
Terminology: define false positive
wrongly reported as having the condition
Terminology: define false negative
wrongly reported as not having the condition
How do you give ‘informed choice? about screening tests?
- explain it’s optional
- check understanding of screening versus diagnosis
- explain how the tests are done
- explain and agree how and when results will be given
- discuss the meaning of the potential test results
- document decision
What antenatal screening tests are offered in the UK?
- blood - sickle cell and thalassaemia
- infectious diseases - syphillis, hep B, HIV
- fetal anomalies - downs, edwards, pataus
When are women offered screening for SCD and Thal.?
by 8-10 weeks gestation (at booking)
Observing a high or low prevalence of SCD or Thal. What is it based on?
family origin and blood results
If pregnant women are identified as a carrier of SCD or Thal, what happens next?
The baby’s father will be offered the screening asap
If both parents are identified as a carrier of SCD or Thal what is offered to them and their baby?
- referral for counselling
- offer prenatal diagnosis by 12+6 gestation
- all babies offered screening for SCD through heel prick test postnatal day 5
What infectious diseases are screened for in pregnancy?
HIV, Hepatitis B and Syphilis
What care is to be given to women screened positive for infectious diseases?
referred for appropriate specialist care in line with programme standards
What care is to be given to babies born to mothers with HIV and syphilis?
Should be followed at birth in line with clinical guidelines
What care is to be given to babies born to mothers with Hepatitis B?
Vaccinated within 24 hours of birth and referred for follow up vaccinations 1, 2 and 12 months old with a blood test to test the effectivity status of the vaccine
What 3 main fetal anomalies are screened for?
Down Syndrome, Edward’s and Patau’s
What does the combined test involve?
A blood test and nuchal translucency ultrasound scan
When is a combined test done?
between gestation 11-14
What is the use of blood and NT test in the combined test screenings?
blood - measure levels of substances found in the blood
NT - measure fluid at the back of baby’s neck
When you are a late booker, what test is offered to you for fetal anomalies?
Quadruple test between gestation 14-20
What are potential problems of the quadruple test?
- only screens for Downs
- reduces choices of termination
What are the two diagnostic ‘further’ tests for high chance babies?
Amniocentesis
Chorionic Villus Sampling
What is amniocentesis?
removing a small amount of fluid from around the baby (amniotic fluid) using a fine needle. Usually performed after 15 weeks of pregnancy.
What is Chorionic Villus Sampling (CVS)?
Removing a tiny sample of the placenta using a fine needle. Usually permoed between 11-14 weeks.
What are the risks of the diagnostic/’further’ tests?
1-2 in 100 chance of miscarriage
List other anomalies screened for?
- open spina bifida
- anencephaly
- cleft lio
- diaphragmatic hernia
- gastroschisis
- exomphalos
- cardiac anomalies
- bilateral renal agenesis
- lethal skeletal dysplasia
- trisomy 18 or 13
What is open spina bifida?
no skin covering, bottom of the spinal cord exposed
What is gastroschisis?
intestines on the outside of the baby’s body
What is exomphalos?
intestines on the outside of baby’s body in the sac
What is anencephaly?
absence of major portion of brain, skull and scalp
When are haemoglobin levels tested and why?
at booking and 28 weeks to screen for anaemia to enable iron treatment if necessary
When is blood group and rhesus status tested and why?
Booking and 28 weeks to determine whether anti-D is necessary
When is syphilis tested?
at booking to begin necessary treatment
When is SCD and thalassaemia treated?
by 10 weeks (at booking usually)
When is HIV tested and why?
At booking so interventions can be offered to infected women
When is Hepatitis B tested and why?
at booking so postnatal can be offered to infected women and babies!
What are some advantages to screening?
- informed choice
- preparation for birth and parenthood
- counselling opportunities
What are some disadvantages to screening?
- not 100% accurate
- anxiety around the tests and the result
