Haemoglobinopathies and Obstetric Haematology

Question 1

What are the main haematological changes during pregnancy?

Answer 1

Plasma vol. expands by 50%
Red cell mass expands by 25%= haemodilution and decreased in relative MCH +/-anaemia
Increased requirement for Fe and folic acid
Leucocytosis- immature WBCs sometimes seen in peripheral blood
Thrombocytopenia
Hypercoaguable stage (liver increased production of clotting factors)

Question 2

Overall, is pregnancy a hyper or hypo coagulable state?

Answer 2

Hypercoaguable- settles down 6-8 weeks after birth

Question 3

Detection of what foetal haemaglobinopathy would prompt genetic counselling and the decision to terminate the foetus

Answer 3

Thalassamia major (B)

Question 4

How is thalassaemia inherited?

Answer 4

Autosomal recessive

Question 5

What are the most common single gene disorder

Answer 5

Thalassaemias

Question 6

Why does alpha thalassamia have a worse prognosis than beta thalassaemia?

Answer 6

Alpha globin is present in adult and foetal haemoglobin

Question 7

What are the lab findings for alpha and beta thalassaemia trait?

Answer 7

Microcytic, hypochromic RBCs with raised red cell count

Question 8

Lifespan of sickle cells

Answer 8

10-20 days

Question 9

What type of anaemia do you get in sickle cell disease?

Answer 9

Haemolytic anaemia

Question 10

What type of mutation causes sickle cell disease?

Answer 10

Point mutation in the beta globin gene-

Question 11

What is the result of the mutation in sickle cell disease?

Answer 11

Insolubility of HbS in deoxygenated state

Question 12

4 clinical features of sickle cell disease

Answer 12

Vaso-occlusive crisis
Visceral suquestrian crisis
Aplastic crisis
Increased susceptibility to infection

Question 13

Increased sickling and blockage of small vessels. Triggers include infection, dehydration, acidosis and deoxygenation. Hand- foot syndrome in children- infarction of metaphyses of small bones- pain and blistering

Answer 13

Vaso-occlusive crisis

Question 14

Sickling with pools of RBCs in liver and spleen or lungs. Partly responsible for acute chest pain

Answer 14

Visceral sequestrian crisis

Question 15

Follos B19 paravirus. Arrest of erythropoieisis is normal, but in HbS patients, rapidly causes severe anaemia.

Answer 15

Aplastic crisis

Question 16

Treatment for sickle cell disease

Answer 16

Prophylactic vaccines
Folic acid
Hydration
Transfusion for severe anaemia 
Oral hydroxycarbamide, increases Hbf and inhibits prothrombotic state, increases MCV
Stem cell transplant

Question 17

Clincial features of thalassaemia major

Answer 17

Anaemia at 3-6 months when foetal to adult Hb chain occurs. Failure to thrive, infection, pallor, mild jaundice, bone marrow hyperplasia esp skull ‘hair on end’ appearance on x ray. osteoporosis= bone marrow expansion

Question 18

Lab findings for thalassaemia major

Answer 18

20-60g/L Hb
low MCH
low MCV
Hypochromic, microcytic cells

Question 19

Life expectancy for thalassaemia major

Answer 19

13 years

Question 20

Treatment for thalassaemia major

Answer 20

Transfusion to suppress natural erythropoiesis.

Question 21

Complications of treatment for thalassaemia major

Answer 21

No excretory mechanism for Fe, by 10-12 years- severe iron overload and toxicity.

Question 22

Solution for iron toxicity

Answer 22

Iron chelation therapy-promotes excretion of iron in urine and faeces-subcutaneous desferrioxamine