Sickle cell disorders

Key Information

Appropriate Tests


Disorders in which the red cells contain sickle haemoglobin (HbS) and undergo sickling / deformation when deoxygenated resulting in capillary/small vessel obstruction and tissue hypoxaemia. The sickle cell disorders occur with high frequency in West African derived populations and the Middle East.

Full blood count, Blood film; 'sickle preparation'; Haemoglobin electrophoresis; HbS (qualitative test and quantitation); HbA2, HbF estimation.

Family studies.

Prenatal diagnosis - Molecular genetics - genetic disorders.

Sickle cell disease (HbSS)

Clinically severe (usually). Pregnancy is a high risk time for patients with sickle cells disease and all patients should be referred to specialist units, even if they have had previously mild disease.

Sickle cell/ß thalassaemia 

Double heterozygous state; clinical severity variable, depending on the type of ß thalassaemia.

See Thalassaemia

Sickle cell/ß± thalassaemia 

Double heterozygous state; clinical severity variable, depending on the type of ß thalassaemia. The disease may become severe with precipitants such as pregnancy.

See Thalassaemia

Sickle cell/haemoglobin D disease

Double heterozygous state (HbSD).

Sickle-cell haemoglobin C

See Haemoglobinopathy

Sickle cell haemoglobin D

See Haemoglobinopathy

Sickle cell trait

Heterozygous state (HbAS) - these patients do not sickle and are phenotypically normal. These patients rarely encounter anaesthetic problems.

The red cell indices may be normal.

Couples from high risk populations should be screened using Haemoglobin electrophoresis and thalassaemia screen, since at risk couples will be missed by reliance on full blood count alone.

Precipitants of sickling








Low temperature




Folate deficiency



This is an important cause of morbidity and mortality.

Manifestations of sickling


Haemolytic anaemia

See also Haemolysis



  • Splenic infarction

See Splenic atrophy/absence

  • Splenic atrophy


Pain crises/vaso-occlusive crises


  • Bone pain


Chest syndrome

A potentially life threatening syndrome of progressive pulmonary infiltrates, with increasing hypoxaemia and increased sickling.

Splenic sequestration

Particularly in children, where there can be rapidly progressive anaemia.

  • Aplastic crises
Bone marrow aspiration may be indicated.

Leg ulcers


Renal papillary necrosis


Renal medullary carcinoma


Bony infarction and avascular necrosis


Subarachnoid haemorrhage





With previous transfusion therapy.

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