Hemolytic disease of the newborn. Flashcards
hemolytic diseases is one of the disease which can cause what ?
fetal hydrops
what is fetal hydros ?
accumulation of edema fluid in the fetus during intrauterine growth
what are the types of fetal hydros ?
there are two types :
immune hydros - it is caused by rh blood incompatibility
non immune hydros :
cardiovascular defect
chromosomal abnormalities = turner syndrome
fetal anemia , trisomy 21 and 18 because of the structural cardiac abnormalities
for hemolytic disease of the fetus to occur what are the conditions we need ?
rh negative mother
a secondary pregnancy with rh positive fetus
and the first pregnancy was also rh positive
rh positive father
how does rh antibodies differ from the ABO system
rh negative mother no not naturally produce rh antibodies only once exposed unlike the ABO blood group
what is the pathophysiology of the heolytic disease of the new born ?
the mothers blood comes into contact with the rh positive fetus blood
and when it comes into contact they produce memory b cells which produce IgM antibodies against the rh positive antigen
these IgM antibodies cannot cross the placenta
during the second trimester of the next pregnancy when the fetal RBC comes into contact with withe he mother immune system IgG is produced this time
these IgG can cross the placenta and enter into fetal circulation
how can the mother’s blood come in contact with the fetal blood ?
during the last trimester of pregnancy when there is no cytotrophblast playing as a barrier
there can be placental abruption or placental haemorrhage
there can be uterine tear
there can be maternal injuries during labour
abnormalities of the placenta
what is the complication of hemolytic disease ?
hemolytic anemia is produced
= hypoxic injury f the heart and liver
hypoxic injury to the liver = decreases plasma protein synthesis low as 2-2.4 mg/dl
cardiac hypoxia = cardiac decompensation and failure, the heart pumps more and more blood is made however it cannot compensate
combo of reduced oncotic pressure and increases hydrostatic pressure result in generalised edema = anascara / hydros fetalis
= jaundice
how can we prevent erythroblastis fetalis ?
when a an rh negative when is carrying an rh positive child we give anti-rh antibodies
these antibodies will immediately bind to the fetal blood and it will be masked from the immune system before it can make a reaction against it
no IgM or memory cells produced
what are other causes of haemolytic disease of the newborn
ABO incompatibility mother is blood type 0
and fetus is A / B /AB
thalessemia
autoimmune hemolytic anemia
a person with rh negativee has what genetic trait
autosomal recessive trait dd
however if the parent has one D
it wil dominate
what are other ways there can be fetal maternal mix and bleed ?
amniocentesis
ectopic pregnancy
miscarriage / abortion
rh incompatibility can present itself from mild from to severe h=frm describe it
mild = jaundice within 24 hours of life
severe form - hydros fetalis/ erythroblastic fetalis
petechia / pupura
stillborn or death shortly after delivery
what is the clinical presentation of the baby in the severe form
pale high output heart failure enlarged liver and spleen generalised edema ascots resp distress kernicterus
how can we diagnose rh incompatibility ?
direct coombs test in infant
- detect maternal anti-d antibodies
it is direct because the anti immunoglobulins binds directly to the internal anti d immunoglobulin the carts there fetal blood cells
indirect coombs test for mother
they find indirect effect evidence of the harmful maternal antibodies
