Congenital
Prior splenectomy for:
Previous hypersplenism
Sickle cell disease
Immune thrombocytopenic purpura, TTP, autoimmune hemolytic anemia
Hodgkin's lymphoma
Thalassemia
Hereditary spherocytosis<unk>  injury (rupture/hemorrhage)
Functional
Sickle cell disease
Previous hypersplenism
Sickle cell disease
Immune thrombocytopenic purpura, TTP, autoimmune hemolytic anemia
Hodgkin's lymphoma
Thalassemia
Hereditary spherocytosis<unk>  injury (rupture/hemorrhage)
Sickle cell disease
Asplenic patient
Bacterial infection 
Combative patient
Streptococcus pneumonia
The obese patient
Haemophilus influenzae type B
Severe anemia in Jehovah's Witness patients
Neisseria meningitidis