Sickle Cell Disease
๐ฉธ Sickle Cell Disease (SCD) โ Inform haematology immediately if a known HbSS/SC patient is admitted.
๐ In SCD, red cells become โsickle-shapedโ under hypoxic stress โ vaso-occlusion, haemolysis, and multiorgan complications.
๐ About
- ๐ Chronic haemolytic anaemia, mainly affecting people of Afro-Caribbean origin.
- โก Most severe: HbSS (โ70% UK cases).
- ๐ก HbSC: milder but still crisis-prone.
- ๐งฌ HbAS (trait): usually asymptomatic, but gene carrier & protective against malaria.
- ๐ Patients often carry a haemoglobinopathy alert card.
๐งฌ Aetiology
- ๐งช Point mutation: Valine replaces glutamic acid at position 6 of ฮฒ-globin.
- ๐ HbS polymerises at โ Oโ โ rigid, sickled cells โ vaso-occlusion + haemolysis.
- ๐ Diagnosis: Hb electrophoresis or HPLC.
โก Precipitants of Sickling
- โฐ๏ธ Deoxygenation (high altitude, hypoxia).
- ๐ง Dehydration.
- ๐ค Infection, fever.
- ๐คฐ Pregnancy, ๐ฐ stress, ๐งช acidosis.
๐ฉบ Types of Haemoglobinopathy
- ๐ด HbSS: severe, anaemic, recurrent crises.
- ๐ก HbSC: milder, vaso-occlusion possible.
- โซ HbS/ฮฒ-thalassaemia: resembles HbSS.
- ๐ข Trait (HbAS): asymptomatic carrier.
๐ฉโโ๏ธ Clinical Presentation
- ๐ฌ๏ธ Acute chest syndrome: fever, dyspnoea, chest pain, hypoxia, falling Hb โ ICU risk.
- ๐ฆด Painful vaso-occlusive crisis: bone pain (esp. long bones, spine, dactylitis in children).
- ๐ชซ Splenic sequestration: sudden splenomegaly + hypovolaemia (esp. children).
- ๐ง Neurological: stroke from cerebral sickling.
- ๐ Priapism: prolonged painful erection โ urgent input.
- ๐ฆ Aplastic crisis: parvovirus B19 โ profound anaemia.
- ๐ Cholecystitis: gallstones from chronic haemolysis โ jaundice + RUQ pain.
๐ Complications
- ๐ฌ๏ธ Acute chest syndrome.
- ๐ก๏ธ Recurrent infections (autosplenectomy โ pneumococcus, Salmonella osteomyelitis).
- ๐ฆต Avascular necrosis (femoral head common).
- ๐ฉธ Renal papillary necrosis, haematuria.
- ๐ Priapism โ risk of erectile dysfunction.
- ๐ฉน Leg ulcers, hepatosplenomegaly, pulmonary fibrosis.
๐ Investigations
- ๐ฉธ FBC โ anaemia, โ reticulocytes.
- ๐ฌ Blood film โ sickled cells, target cells.
- ๐ฆ Sepsis screen if febrile.
- ๐ฌ๏ธ ABG & sats โ hypoxia (chest crisis vs PE).
- ๐ผ๏ธ CXR โ consolidation/effusion.
- ๐ง CT/MRI brain โ if neurological deficit/stroke.
- ๐งช U&E, LFTs, LDH, bilirubin, haptoglobin โ haemolysis & organ function.
๐ Management of Acute Crisis
- ๐ ABCDE + senior review early.
- ๐ง Hydration: IV saline (avoid overload).
- ๐ Pain relief: Morphine within 30 mins, titrate + NSAID + paracetamol. Add laxatives.
- ๐ฌ๏ธ Oโ if sats <95%.
- ๐ฆ Antibiotics if fever/sepsis (cover pneumococcus/Salmonella).
- ๐ Consider exchange transfusion for: acute chest, stroke, priapism, multi-organ failure (target HbS <30%).
๐
Long-Term Management
- ๐ Hydroxyurea โ โ HbF, โ crises.
- ๐ Vaccinations: pneumococcus, Hib, meningococcus.
- ๐ Prophylactic penicillin in children.
- ๐งฌ Bone marrow transplantation โ curative in selected patients.
๐ Exam / OSCE Pearls
โ ๐จ Sickle crises are medical emergencies โ treat pain + fluids promptly.
โ ๐ค Always rule out infection.
โ ๐ฌ๏ธ Chest crisis: Oโ + antibiotics + consider exchange transfusion.
โ ๐ Ask about priapism, ๐ง neuro symptoms, ๐ชซ splenic sequestration in any acute admission.
๐ References
Cases โ Sickle Cell Disease
- Case 1 โ Vaso-occlusive crisis ๐ฅ: A 19-year-old man with known HbSS genotype presents with sudden severe generalised bone pain, especially in his long bones and back. He is febrile (38.1ยฐC) and tachycardic. FBC: Hb 7.8 g/dL, WCC 15.0 ร10โน/L. Diagnosis: acute painful crisis in sickle cell disease. Managed with opioid analgesia, IV fluids, oxygen, and infection screen with empiric antibiotics.
- Case 2 โ Acute chest syndrome ๐ซ: A 24-year-old woman with sickle cell disease presents with pleuritic chest pain, fever, cough, and increasing shortness of breath. CXR: new bilateral infiltrates. ABG: hypoxia. Diagnosis: acute chest syndrome (vaso-occlusion in pulmonary vasculature ยฑ infection). Managed with oxygen, antibiotics, analgesia, and exchange transfusion if hypoxia worsens.
- Case 3 โ Stroke in childhood ๐ง : A 10-year-old boy with sickle cell disease is brought with sudden right-sided weakness and slurred speech. CT head: ischaemic stroke. Bloods: Hb 6.9 g/dL. Diagnosis: ischaemic stroke due to sickle cell vaso-occlusion. Managed acutely with exchange transfusion and long-term with chronic transfusion programme and hydroxycarbamide.
Teaching Point ๐ฉบ: Sickle cell disease is an inherited haemoglobinopathy (HbSS) leading to haemolysis and vaso-occlusion. Key complications include: painful crises, acute chest syndrome, stroke, splenic sequestration, infections, chronic organ damage. Hydroxycarbamide, vaccination, prophylactic antibiotics, and transfusion programmes improve survival.