Haematology Flashcards
what is haemolytic disease of the newborn
breakdown of RBCs in the neonate due to rhesus incompatibility
- rhesus D positive baby born to rhesus D negative mother
- mother makes antibodies to baby’s rhesus D (anti-D antibodies) – these cross placenta and attach to foetal RBCs
- immune réponse causes haemolysis of RBCs – anaemia + high bilirubin – jaundice
what test is +ve in haemolytic disease of newborn
Direct Coombs test
what is given to babies at birth to prevent haemolytic disease of newborn
IM VIT K
when are rhesus -ve mothers offered prophlyactic anti-D
28 + 34 Weeks
15000 units
what events during pregnancy would a rhesus -ve mother get anti-D
ectopic pregnancy
amniocentesis
termination of pregnancy
trauma – vaginal bleeding / miscarriage
dose of anti-D given after delivery to rhesus -ve mother
500 units
when would anti-D not be given after delivery
if Coombs test +ve / infant bilirubin raised
– it is too late
inheritance of sickle cell anaemia
autosomal recessive - abnormal gene for beta globin on chromosome 11
- one abnormal copy = sickle cell trait
- two abnormal copies = sickly cell disease
management of sickle cell anaemia
avoid dehydration / infective causes of sickle crisis
antibiotic prophylaxis – penicillin V
hydroxyurea – can stimulate HbF (fetal haemoglobin production), has a protective effect
what can cause an aplastic crisis in sickle cell anaemia
parvovirus B19
what is a splenic sequestration crisis
occurs in sickle cell anaemia
- RBCs block blood flow in the spleen
- causes an enlarged + painful spleen – leads to anaemia + circulatory collapse
- tx: blood transfusions / fluid resuscitation
- splenectomy in recurrent cases
what is idiopathic thrombocytopenic purpura (ITP)
Immune mediated low platelet count causing a purpuric rash (non-blanching)
what type of reaction is ITP
type 2 hypersensitivity – antibodies destroy platelets
- can be spontaneous or following a viral infection
inheritance of Thalassaemia
autosomal recessive
what type of anaemia is seen in Thalassaemia
microcytic
what are the types of thalassaemia
alpha – defect on chromosome 16
beta – defect on chromosome 11
what are the subtypes of Alpha thalassaemia
mild: 1 or 2 alleles affected – microcytic but Hb level normal
moderate: known as HbH disease – microcytic anaemia with splenomegaly
severe: Hydrops fetalis (Barts disease)- all 4 alleles affected, death in utero
what are the subtypes of beta thalassaemia
beta thalassaemia trait – one abnormal beta globin gene + one normal. Causes mild microcytic anaemia
beta Thalassaemia intermedia – two abnormal copies. requires occasional blood transfusions for more significant anaemia
beta thalassaemia major – no functioning beta globing genes. severe anaemia + failure to thrive. Requires regular blood transfusions + splenectomy
complication of thalassaemias
iron overload
- patens require iron chelation if having repeated transfusions
inheritance of hereditary spherocytosis
autosomal dominant
- red blood cells are sphere shaped making them fragile + easily destroyed in spleen
presentation of hereditary spherocytosis
jaundice anaemia gallstones splenomegaly aplastic crisis -- parvovirus infection. no reticulocyte response to haemolysis
how is diagnosis of hereditary spherocytosis made
+ve family history
blood film showing spherocytes
raised reticulocytes
raised MCHC (mean corpuscular Hb concentration)
management of hereditary spherocytosis
folate supplement + splenectomy
inheritance of G6PD deficiency
X linked recessive
- deficiency in G6PD which helps combat oxidative stress
symptoms of G6PD deficiency
anaemia
intermittent jaundice
splenomegaly
gallstones
what things can trigger jaundice in G6PD deficiency
broad beans
antimalarials
Sulfonylureas
infections
what is seen on blood film in G6PD deficiency
Heinz bodies
