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Internal MedicineHematologySickle Cell Vaso‑Occlusive Crisis

Sickle Cell Vaso‑Occlusive Crisis

Must-Not-Miss / Red Flags

  • Acute chest syndrome: fever, chest pain, pulmonary infiltrates – leading cause of death in SCD
  • Splenic sequestration: rapid splenic enlargement and hypovolemic shock (mostly in children)
  • Priapism: prolonged, painful erection – urologic emergency
Patient Explanation
“You’re having a pain crisis because the sickle‑shaped red cells are blocking small blood vessels. We’ll give you strong pain relief and fluids to help the cells flow better.”
Board Fact
“The most common precipitant of VOC is infection, but dehydration, cold exposure, and stress are also triggers.”
ICD-10
D57.00

Definition & Core Concept

Vaso‑occlusive crisis (VOC) is the most common complication of sickle cell disease, caused by polymerization of HbS under deoxygenated conditions, leading to microvascular occlusion, tissue ischemia, and severe pain.

Epidemiology & Risk Factors

  • SCD affects ~100,000 people in the US, predominantly African Americans
  • VOC accounts for >90% of SCD hospitalizations
  • Average life expectancy: 50‑60 years with optimal care

Pathophysiology (Rule of 3)

  1. Deoxygenation of HbS → polymerization of hemoglobin S → sickled RBCs
  2. Sickled cells adhere to endothelium → activation of inflammatory cascade → vaso‑occlusion
  3. Tissue ischemia and infarction → severe pain, organ dysfunction

Clinical Presentation

  • Severe, often diffuse or localized bone pain (long bones, back, chest)
  • Fever may be present (can be due to crisis itself or infection)
  • Fatigue, pallor (anemia)

Diagnostic Workup

CBC: hemoglobin drop from baseline, leukocytosis. Reticulocyte count: elevated (if adequate marrow response). Chest X‑ray: rule out acute chest syndrome. Blood cultures: if fever. Type and screen: for possible transfusion.

Management Protocol

  1. Pain management: aggressive opioid therapy (Morphine 0.1 mg/kg IV or Hydromorphone) on a scheduled basis, not PRN; PCA pump preferred
  2. IV fluids: isotonic crystalloid at maintenance rate (avoid over‑hydration)
  3. Oxygen: only if hypoxic (SpO₂ <92%)
  4. Transfusion: simple transfusion for symptomatic anemia (Hb drop >2 g/dL from baseline); exchange transfusion for acute chest syndrome or stroke
  5. Antibiotics: if infection suspected (Ceftriaxone 1‑2 g IV)

Complications & Prognosis

  • Acute chest syndrome (mortality 1‑3%)
  • Stroke (ischemic in children, hemorrhagic in adults)
  • Multi‑organ failure from severe VOC

ICU Criteria

ICU admission if: acute chest syndrome requiring ventilation, stroke, multi‑organ failure.

Clinical Vignette

A 22‑year‑old man with sickle cell disease (HbSS) presents with severe pain in his lower back and legs for 12 hours. He rates pain 10/10. His baseline Hb is 9 g/dL; current Hb is 7.5 g/dL. He has a low‑grade fever of 38°C.

Pearls & Pitfalls

  • Pain is the most common presentation of VOC – believe the patient’s pain report; there is no objective measure.
  • Incentive spirometry reduces the risk of acute chest syndrome in patients with chest or back pain.

Discharge & Follow-Up

Hydroxyurea therapy for VOC prevention (increases HbF). Folic acid supplementation. Regular outpatient hematology follow‑up. Immunizations (pneumococcal, meningococcal, Hib).

Literature & Guidelines

ASH 2024 Guidelines for Sickle Cell Disease Management. PMID: 38591245.

Personal Clinical Notes