In sickle cell disease, vaso-occlusive crises most commonly affect which anatomical site?
A. Spleen
B. Kidneys
C. Femoral head and humeral head (bones)
D. Meninges
Explanation
Most Common Site of Vaso-Occlusive Crisis in SCD
Key Point
The femoral head and humeral head (long bones) are the most common sites of vaso-occlusive infarction in sickle cell disease, causing acute bone pain crisis and chronic osteonecrosis.
Why Bones Are Most Commonly Affected
1.
High metabolic demand — bone marrow has high oxygen consumption
Osteonecrosis (avascular necrosis) of the femoral head is a major cause of morbidity in adult SCD patients, often requiring hip replacement.
Clinical Pearl
The hand-foot syndrome (dactylitis) is the earliest manifestation of vaso-occlusion in infants with SCD, typically presenting between 6 months and 2 years of age, affecting the small bones of hands and feet.
Mnemonic — Sites of Infarction in SCD: "BONES"
Bones (femoral, humeral heads) — most common
Organ (spleen, kidney, liver)
Neurologic (brain, stroke)
Endothelial (lungs, ACS)
Systemic (multi-organ involvement)
Warning
Do not confuse acute bone pain crisis (vaso-occlusive) with osteomyelitis in SCD; both can present similarly, but SCD patients are at risk for both conditions—culture and imaging are essential.
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