Physiology · Blood Physiology and Hematology Basics

In sickle cell disease, a patient with acute painful vaso-occlusive crisis develops sudden severe anemia with reticulocytopenia and a spleen larger than the baseline. The most likely diagnosis is:

  • A Aplastic crisis caused by Parvovirus B19 infection of erythroid progenitors
  • B Hemolytic crisis with intravascular hemolysis releasing heme that overwhelms haptoglobin
  • C Acute splenic sequestration crisis caused by sudden trapping of sickle red cells in the spleen
  • D Megaloblastic crisis due to folate depletion from chronic hemolysis and increased erythropoiesis
Correct answer: C. Acute splenic sequestration crisis caused by sudden trapping of sickle red cells in the spleen

Explanation

Acute splenic sequestration crisis occurs predominantly in young children with SCD (before autosplenectomy is complete) and involves rapid sequestration of sickled RBCs in the splenic sinusoids, causing sudden painful splenomegaly, severe acute anemia, and preserved (or even elevated) reticulocyte count (reactive erythropoiesis). It requires urgent blood transfusion and can be life-threatening. Aplastic crisis (Parvovirus B19) presents with absent reticulocytes, no splenomegaly change, and normal bilirubin (no hemolysis). Hemolytic crisis has high reticulocytes and elevated bilirubin but stable spleen. Megaloblastic crisis has macrocytes and hypersegmented neutrophils.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

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