Haematological Disease Flashcards
What is the increase in the requirement for iron in pregnancy?
2-3x
What is the increase in requirement for folate in pregnancy?
10-20x
What is B12 deficiency caused by?
Dietary deficiency
IBD
Pernicious anaemia
- intrinsic factor antibodies, leading to B12 malabsorption
What blood test provides an accurate assessment of iron stores?
Serum ferritin
What obestetric outcomes is iron deficiency associated with?
LBW
PTB
Increased risk PPH
What does Sickle Cell Disease lead to?
- Anaemia, chronic haemolytic
- Painful vaso-occlusive crises
- Infections, partly due to loss of splenic function from auto-infarction
- Acute chest syndrome
Describe Sickle Cell Haemoglobin (HbS)
Variant of the beta-chain of haemoglobin
HbA usually made up 2 alpha and 2 beta chains - in sickle cell consists of 2 alpha and 2 HbS chains
Glutamate is replaced by valine
In low oxygen tension, the deoxygenated HbS polymerises forming fibrous precipitates causing the erythrocytes to assume a sickle shape which is inflexible and blocks small vessels leading to an occlusive crisis
What are the three main types of sickle crisis
- Vaso-occlusive symptoms and tissue infarction with severe pain
- Sequestration: splenic sequestration occurs mainly during childhood
- Aplastic: often associated with parvovirus infection
How is Sickle Cell Disease diagnosed?
Haemoglobin electrophoresis
What are the obstetric outcomes associated with Sickle Cell Disease?
Perinatal mortality 4-6x
Miscarriage
SGA
PT
PET
Placental abruption
Fetal distress
CS
What are the maternal risks in Sickle Cell Disease
VTE
Bone marrow embolism
Maternal mortality 2.5%
Infection
What is essential thrombocythaemia
Isolated thrombocytosis
Myeloproliferative disorder
May be associated with Haemorrhagic and thromboembolic manifestations
What is the DDx for Thrombocythaemia
Infection and inflammation
Post-surgical acute phase response
Reactive, following blood loss
What are the obstetric outcomes for essential thrombocythaemia
FGR
Possibly related to placental thrombosis
What is the treatment for platelet > 600, in pregnancy?
Low dose aspirin
Inhibits platelet aggregation and thrombosis
Inteferon-alpha is also used for myelosuppresion
LMWH is used in addition if there is a previous history of thrombosis
What are the causes of thrombocytopenia in pregnancy?
Spurious result
Gestational thrombocytopenia
Immune thrombocytopenic purpura
PET / HELLP
DIC
HUS / TTP
HIV
Drugs
Infections
SLE and APS
Bone marrow suppression
What is the pathogenesis of ITP?
Autoantibodies against platelet surface antigens
Peripheral platelet destruction by the reticuloendothelial system, particularly the spleen
How does ITP affect the fetus?
Antiplatelet IgG can cross the placenta
And cause fetal thrombocytopenia
The level of risk fo the fetus is small, the risks of fetal Plt count <50 is 5-10%
Accurate prediction of the fetal platelet count from the maternal platelet count / antibody level is not possible
0-1.5% risk of antenatal / neonatal intracranial haemorrhage
How often should platelets be monitored in ITP?
Monthly
More frequently in the third trimester
When is treatment required in ITP in the 1st / 2nd trimesters?
Symptomatic with bleeding
Plt < 20
The count needs to be increased prior to a procedure such as CVS
When does ITP need to be treated in the 3rd trimester?
Plt < 50
Plt 50-80 may warrant treatment to facilitate regional anaesthesia
What is the treatment for ITP?
Corticosteroids
Prednisolone
If resistant to above, IVIG
- delayed clearance of IgG coated platelets from the maternal circulation
In Rh positive women - Anti-D IgG
- creates a decoy to competitively inhibit the destruction of antibody -coated platelets
Azathioprine, Ciclosporin
Splenectomy in extreme cases (should be avoided in pregnancy if possible)
Platelet transfusion for bleeding or prior to surgery
What are obstetric causes of DIC?
Haemorrhage, particularly abruption
PET / HELLP
AFE
Infection
Retention of dead fetus