Immune System Flashcards
Why does the immune system change
Paternal antigens are expressed on fetal cells from as early as as the 8-cell stage which risks the foetus being rejected as a foreign body
Maternal mound system must adapt to avoid rejecting the foetus
What are the local changes in the decidua
Hig levels of progesterone, corticosteroids and/or HCG may act locally on the uterus to change the immune response to stop fetal rejection.
During pregnancy, thedecidua contains a high number of immune cells such as macrophage, natural killer cells and regulatory T cells.
Absence of these immune cell lead to termination of the pregnancy
What do macrophages do
Remodel tissue and clear debris
Hat do oregulatory T cells do
Acts as brakes they limit the response of other T cells hence they rotect the foetus from the immune response
What do natural killer cells do
Recognise and destroy invading trophoblastic cells
what do rising level of progesterone do
Cause a natural suppression in immunity
However pregnancy does not necessarily make the women moe susceptible to infectious disease - the immune system reponds differently to different micro organisms
What does the white blood cell count do
Increasing oestrogen levels abuse the white cell count mainly neutrophils to rise. This eats around 30/40 then plateaus until labour when it rises slightly.
The proportion of of t helper cells declines to suppress the immune response reduce capacity for making antibodies.
Listeriosis
Pregnant women may avoid mould-ripened soft cheeses, unpasteurised milk products and dncooked smoked fish. There is a small chance of listeriosis leaving to miscarriage or stillbirth
Toxoplasmosis
Infection from toxoplasma Gondi parasite usually from raw uncooked meat or handing cat faeces. Can result in miscarriage, stillbirth and damage to fetal brain, eyes and organs.
Salmonella
From eating raw or partially cooked unvaccinated hens egg. Risk of food poising
Commmon antenatal infections
Thrush
Group b strep
Parvovirus
Rubella
Hep B
HIV
Covid
Intrapartum infections
Group b strep
Chlorioamnionitis
Postnata infection
Strep a sore throat
Strep B
Thrush
Infections in neonat
Group B strep
Latrogenic lesions - cuts from forceps ventouse or c section
Viral infections
Thrush in mouth
Eye infection - chlamydia or gonorrhoea
Cord infection
What is the midwife role
Health promotion - dietary and lifestyle factors
Screening test - blood takin
Identification of unwell mother or baby - awareness of signs of infection
What is offered at the booking appointment
Offer of blood grouping and antibody screen via blood test
Results ABO group, RhD status, and presen of antibodies
What happens if RhD positive
No action required
What happens if RhD negative
Offer prophylactic anti D at 28/40
What happens if no antibodies
No action required
What if antibodies are present
Referral and further monitoring required
What happens at 28/40 appointment
Repeat screen for blood group and antibodies
RhD enegative - administer 1500IU prophalytic anti D via intramuscular injection
When are additional anti D needed
Before 12/40 - heavy or repeated bleeding, miscarriage,ectopic pregnancy or molar pregnancy
After 12/40 - any vaginal bleeding
The dose depends on gestational age and it should be given within 72 hours of the potentially senitising event -potential for maternal and fetal blood to have met
Less than 20/40 - 250IU intramuscular as minimum dose
20/40 or more 500IU intramuscular as minimum
What are the associated blood tests
Kleihauer
Coombs
Blood grouping
Kleihauer blood film
Test to estimate the volume of the veto - maternal haemorrhage
Maternal blood tested for the presence of fetal red blood cell
Th lab staff can then advise on necessary dose of anti D
This maternal blood test is usd after sensitising events from 20/40 and also after the birth of the baby
Coombs test
Test to measure amount of antibodies present this test can use maternal blood in pregnancy to test for presence of antibodies
This test an also use babys blood from the cord to test for presence of harmful antibodies
Positive - antibodies are present
Negative - antibodies are not present
Blood grouping
The test the ABO and RhD status
The test is used for antenatal ( maternal)and neonatal cord blood)
If baby is RhD positive
No action required - mother and baby same
If baby is RhD positive
Anti D is required - mother and baby different
Why does administration of anti d matter
If pregnant woman develop high levels of anti D antibodies, they can travel through the placenta and destroy fetal red blood cells - isoimmunisation
What is haemolytic disease of the fetus/newborn
Destruction of fetal red bloood cell results in fetal anaemia and less oxygen reaches fetal tissu, odeoma and dcaardiac failure can develop
Lesser degrees f red cell destruction may result in fetal anaemia only, while extensive haemolysis can abuse hydropower fetal is and fetal death.
Infants are at a high risk of pathological jaundice and may require intrauterine and / or neonatal exchange blood transfusions
Practic implications
Informed consent - full discussion about blood test offered
Documentation of screening choice- accept and decline
Venepuncture - obtaining blood samples
Reviewing results - interpreting blood test results
Adminstration - giving anti d without prescription via intramuscular injection
Documentation of administration- drug chart and hospital notes
What vaccines do newborn have
8 weeks - 6 in 1 vaccine,rotavirus,Meningitis B
12 weeks: 6 in vaccine 2nd dose), pneumococcal,rotavirus 2nd dose)
16 weeks 6 in 1 vaccine (3rd dose), meningitis B (2nd dose )
