Tuesday, 18 May 2010

Sicke cell anaemia in pregnancy

Genetics
Autosomal recessive disorder
Single point mutation in β-Globin chain in haemoglobin.

Diagram explaining the inheritance 




Types of sickling conditions

(i)Homozygous sickle-cell disease(HbSS)
(ii)Sickle cell/HbC(HbSC)
(iii)Sickle cell /Thalassaemia








Clinical features
Common  features
(i)Anaemia due to chronic haemolysis- This is not so marked in HbSC
(ii)Vaso-occlusive crisis
(iii)Aplastic crisis

Other features
(i)leg ulcers
(ii)gall stones
(iii)acute chest syndrome-pleuritic chest pain,tachypnoea,fever


Sickling crisis  in sickle cell trait patients is precipitated by severe anoxia,dehydration or acidosis.

Diagnosis

Diagnosis is made by haemoglobin electrophoresis.

Effect of pregnancy on disease

(i) sickle cell crisis is more common on pregnancy


Effect of disease on pregnancy
(i)fertility is generally unaffected.
(ii)Genetic transmission of the condition to the fetus
(iii)Perinatal & maternal mortality is increased
(iv) increased risk fetal complications : miscarriage,intrauterine growth restriction,preterm labour
(v) increased risk of maternal complications: thromboembolism,preeclampsia, abruption,infections(probably due to hyposplenism) like UTI,puerperal sepsis
















Management
Prepregnancy
(i)Partner testing
(ii)Folic acid supplementation 5mg/day


Antenatal
(i)Multi disciplinary team involving haematologist,geneticist and obstetrician experienced in managing sickle cell disease.
(ii)Folic acid 5mg/day
(iii) Penicillin prophylaxis to prevent pneumococcal infection as a result of hyposplenism.
(iv)partner screening & genetic counselling -Fetal diagnosis by preimplantation genetics in IVF/CVS/Amniocentesis















(v)Regular checking of haemoglobin and mid stream urine

(vi)regular growth scan

(vii) Management of crisis
      (a)Rehydration
      (b)Pain relief-Morphine.NSAID can cause haemolysis.
      (c)early use of antibiotics if infection is likely
      (d)need to keep the patient warm ; well oxygenated.Pulse oxymetry & arterial blood gas may be necessary.
(viii)Blood transfusion may be necessary ex: to correct anaemia

(ix) Value of exchange transfusion is not well defined.Theoretically this increase the proportion of haemoglobin A and suppress the bone marrow from producing red cells with HbS. This may decrease the incidence of crisis but need to be balanced against the risks associated with transfusion.

(x) It is important to recognize & treat infection early.

(xi) The following treatments used to increase HbF need further evaluation in pregnancy
        (I) hydroxyurea
        (II)butyrate
(xii) Tourniquet should not be used.

Intrapartum care
(i)Avoid : dehydration/hypoxia/sepsis/acidosis
(ii)Epidural analgesia is recommended.
(iii) Sickle cell anaemia is not  an indication for caesarean section
(iv)Give oxygen 4-6 l/min
(v)avoid blood loss as much as possible(Active management of third stage)


Postpartum

(i) Dehydration  & infection should be avoided.

(ii) Risk assessment for thromboprophylaxis should be done.

(ii) Contraception should be discussed-Even though oral contraceptive pills have been implicated in increased risk of thrombo embolism , this is not based on any evidence.


RCOG guideline on management of sickle cell disease in pregnancy

Interventions for treating painful sickle cell crisis during pregnancy (Review)


Powerpoint on Sickle cell disease in pregnancy

Another presentation on sickle cell disease in pregnancy

Powerpoint on sickle cell disease



• Nelson-Piercy C. Handbook of obstetric medicine. Taylor & Francis; 2002.
• Swiet MD. Medical disorders in obstetric practice. Wiley-Blackwell; 2002.