In a patient with sickle cell disease, sudden splenomegaly accompanied by signs of hypovolemia indicates which emergency complication?

• A. Splenic Sequestration Crisis
• B. Acute Chest Syndrome
• C. Vaso-Occlusive Crisis
• D. Aplastic Crisis

Answer: (A)

Splenic sequestration crisis is an emergency in sickle cell disease where sickled cells become trapped in the spleen, causing rapid splenic enlargement and pooling of blood. This sudden sequestration leads to a sharp drop in circulating red blood cells and a decrease in blood volume, which explains the signs of hypovolemia. The spleen swells quickly because it suddenly stores a large amount of blood, and without enough circulating volume, the patient can become hypotensive and unstable. This presentation—acute splenomegaly with signs of decreased circulating volume—is classic for sequestration crisis.

Other sickle cell complications don’t fit this picture: acute chest syndrome presents with chest symptoms and new lung infiltrates; vaso-occlusive crisis causes painful episodes in bones and joints without significant spleen enlargement or hypovolemia; aplastic crisis, usually due to parvovirus B19, causes a severe fall in hemoglobin with a low reticulocyte count but does not typically produce sudden splenomegaly or hypovolemia.