Sickle cell disease is an inherited disorder of haemoglobin, the protein in red blood cells that carries oxygen. In this condition, an abnormal haemoglobin S from one parent is combined with another abnormal haemoglobin from the other parent. Haemoglobin S inherited from both parents (genotype HbSS), described as sickle cell anaemia is the most common form.
When oxygen tension is low, haemoglobin S crystallizes and makes the red blood cells sickle shaped. Sickling reduces red blood cell capacity to manoeuvre through very small blood vessels causing vascular blockage and early destruction of red cells. The breakdown of red blood cells and massive pooling of damaged red blood cells in the liver and spleen cause anaemia. Acute illnesses include painful crises, pulmonary embolism, acute chest syndrome and congestive cardiac failure. Therefore, pregnant women with sickle cell disease require careful management.
Depending on the institutional policy, blood transfusion can be given at intervals to a pregnant HbSS woman with relatively few or no symptoms to improve the oxygen carrying capacity of blood by increasing haemoglobin blood concentration and lowering haemoglobin S levels; or only when indicated by the development of medical or pregnancy complications. Giving blood at frequent intervals carries the risks of blood-borne infections and excessive levels of iron.
This review set out to determine whether giving blood at intervals before serious complications occur compared with giving blood only when medically indicated makes a difference to the health of the mother and her baby. The review authors included two controlled trials that randomised 98 women with sickle cell anaemia (haemoglobin SS) before 28 weeks of gestation to one of the two blood transfusion policies. The two trials were of low quality. One trial (72 women) indicated no difference in severe ill health and death of the mother or newborn. There was no difference in the risk of delayed blood transfusion reaction. The two trials suggested giving blood at frequent intervals marginally reduced the risk of pain crisis, with a large degree of uncertainty about the size of the effect, compared with giving blood only when medically indicated. Blood transfusion was delivered at a ratio of four or five to one for prophylactic versus selective blood transfusion, respectively.
Overall, available evidence on this subject is insufficient to advocate for a change in clinical practice and policy.
Okusanya, B.O.; Oladapo, O.T. Prophylactic versus selective blood transfusion for sickle cell disease in pregnancy. Cochrane Database of Systematic Reviews (2013) Issue 12, Art. No.: CD010378. [DOI: 10.1002/14651858.CD010378.pub2]