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

 

Deoxygenation

 

Dehydration

 

Acidosis

 

Low temperature

 

Infection

 

Folate deficiency

 

Pregnancy

This is an important cause of morbidity and mortality.

Manifestations of sickling

 

Haemolytic anaemia

See also Haemolysis

Infection

 

  • 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

 

Retinopathy

 

Haemosiderosis

With previous transfusion therapy.