Sickle Cell Anaemia

Content of This Page

1- Introduction

2- Pathophysiology

3- Clinical Features (Recognize chronic clinical features)

4- Interpret labs and diagnostics

5-Management of acute complications

6- Preventive strategies

7-Indications for transfusion & transplant

8- Complications

9- Prognosis & mortality trends

Introduction

Sickle cell anaemia is a genetic disorder of haemoglobin caused by a point mutation in the β-globin gene (Glu6Val), leading to the production of abnormal haemoglobin S (HbS).

In homozygous (HbSS) individuals → SCA
In heterozygotes (HbAS) → Sickle cell trait (usually asymptomatic)

Pathophysiology

Under low oxygen, HbS polymerises, distorting red blood cells into a sickle shape.

-Sickled RBCs:

Are less flexible → obstruct small vessels (vaso-occlusion)
Have shortened survival → chronic haemolytic anaemia
This leads to:
Tissue ischaemia
Pain crises
End-organ damage over time

Clinical Features

Crisis	Key Features
Vaso-occlusive crisis	Bone pain, dactylitis
Acute chest syndrome	Chest pain, hypoxia, new infiltrate
Stroke	Sudden neuro deficits; more common in children
Sequestration crisis	Splenic/liver pooling → hypovolaemia, shock
Aplastic crisis	Parvovirus B19, ↓ reticulocytes, sudden anaemia
Priapism	Painful, sustained erection

Interpret labs and diagnostics

FBC: Normocytic anaemia, ↑ reticulocytes
Blood film: Sickle cells, Howell–Jolly bodies
Sickling test: Positive
Haemoglobin electrophoresis: Confirms HbS, no HbA in disease

Management of acute complications

Hydration, oxygen, opioid analgesia
Antibiotics if infection suspected
Blood transfusion for severe complications (e.g. stroke, acute chest)
Exchange transfusion in life-threatening crises

Preventive strategies

Folic acid
Vaccinations (pneumococcal, meningococcal, Hib, influenza)
Penicillin prophylaxis in children
Hydroxycarbamide:
- ↑ HbF → reduces crises, need for transfusion

Indications for transfusion & transplant

Simple or exchange transfusion for:
- Stroke, acute chest, surgery
Stem cell transplant:
- Potential cure in severe cases with matched donor
- Limited availability and risks

Complications

Neurological: Stroke, silent infarcts
Pulmonary: Acute chest syndrome, pulmonary hypertension
Renal: Hyposthenuria, CKD
Ocular: Retinopathy
Bone: Osteonecrosis
Splenic: Functional asplenia → ↑ infection risk

Prognosis & mortality trends

Improved with early diagnosis and modern care
Survival into 40s–60s possible

Leading causes of death:
- Stroke, acute chest syndrome, sepsis, multi-organ failure