Reports of acute splenic sequestration crises in adults with sickle cell hemoglobin C disease or sickle cell thalassemia are rare, although an enlarged and distensible spleen persists in half of these patients. Seven episodes of acute splenic sequestration crises in four adults, two with sickle C disease and two with sickle thalassemia, are described. The crises were life-threatening and recurrent in all, but there were no fatalities. One patient had mild steady-state thrombocytopenia suggesting hypersplenism. Technetium 99m/sulfur colloid scanning of the spleen during the acute splenic sequestration crises in three patients showed almost total lack of splenic uptake or decreased uptake with intrasplenic filling defects thought to be splenic infarcts or hematomas on follow-up computed tomographic scanning. The scanning abnormalities resolved following recovery from the crises. Acute splenic sequestration crises probably are common in adults with sickle C disease and sickle thalassemia but may be underdiagnosed or misdiagnosed as splenic infarctions. The hematologic and splenic findings during acute splenic sequestration crises resemble those following splenic vein ligation in animals.

• HL-15160/HL/NHLBI NIH HHS/United States