Table 4.

Categories of hereditary spherocytosis

Category	Probability of hereditary spherocytosis	Criteria
0	Definite	Hemolysis, reticulocytosis, family history of hemolysis (preferably exact diagnosis in first-degree relative), negative antiglobulin test, and increased osmotic fragility or positive EMA test
1	Probable	A. Hemolysis, reticulocytosis, negative antiglobulin test, spherocytes, Scandinavian ethnicity and no better explanation, or B. Highly increased osmotic fragility, reticulocytosis, negative antiglobulin test, Scandinavian ethnicity and no better explanation, or C. Hemolysis splenomegaly and splenectomy, negative antiglobulin test, spherocytosis, Scandinavian ethnicity and no better explanation
2	Likely	Cases fitting category 0, or 1A–C but missing data on one of the following: antiglobulin test, family history, osmotic fragility test, or peripheral smear
Exclusion	Unlikely	Other well-defined hemolytic anemia or negative EMA test (when performed)

Abbreviation: EMA, eosin-5′-maleimide.