Haemoglobinopathies and Obstetric haemotology

Question 1

Changes that occur in haematological values in pregnancy

Answer 1

• Plasma volume expands in pregnancy by 50%
• red cell mass expands by 25%
• haemodilution at week 32
• Neutrophilia from 2nd month to peak at 9-15 weeks
• platelet count falls after 20 weeks and thrombocytopenia found in late pregnancy
• Pregnancy is pro-thrombotic

Question 2

Maternal testing in predicting foetal hamaglobinopathies

Answer 2

High risk pregnancies can have chronic villis biopsy and genetic diagnosis at 8-12 weeks –> termination of affected pregnancies.
Strictural Hb variants can be detected by abnormal mobility on haemoglobin electrophoresis.
Thalassaemias have normal Hb electrophoresis but small pale red cells.

Question 3

a thalassamia

Answer 3

Both Hb A and F have alpha chains.

Mass deletion. Most derious cases in SE asia and med can have loss of all 4 a-globin alleles.

Question 4

b thalassamia : reduced rate of produciton of beta globin chains

Answer 4

Can be due to point mutation.
MINOR: blood picture resembles iron deficicency (small pale red cells)
MAJOR: present with severe anaemia at 1 years old.
blood film abnormal with lots of nucleated red cells.
short stature and distorted limb growth due to premature closure of epiphyes in long bones.
enlarged liver and spleen. X rays show ‘hair on end skull’
Treat: transfusion to maintain haem and to prevent iron overload: IRON CHELATION THERAPY. supress marrow red cell production.

Question 5

Sickle cell disease

Answer 5

Sickle hb S polymerises at low 02 tensions to form long fibrils which distort red cell membrane.
sickle cell shave short lifespan therefore hameolytic anaemia
Blood count: Hb 6-8g
Acute complications: chest syndrome, abdo pain
Chronic: renal disease, avascular necrosis, leg ulcers, hyposplenism.
Treatment: penicliin, analgesia, hydration and hydroxycarbomide to increase HbF.