Absent or defective splenic function is associated with a high risk of fulminant bacterial infections and a high mortality rate. Asplenia and splenic hypoplasia are terms used to indicate complete or partial lack of splenic function.
Loss of splenic function usually occurs as a result of surgical removal or autosplenectomy, ie, infarction in patients with hemoglobinopathies.
Congenital splenic anomalies are usually accompanied by abnormalities in other organ systems, especially cardiac abnormalities, but they may occur in isolation. Polysplenia, ie, bilateral left-sidedness, is also frequently associated with congenital cardiac anomalies.
Patients with polysplenia have multiple spleens, and their splenic function is usually normal. Isolated asplenia or hyposplenia is often diagnosed only after the patient has had a serious, fulminant, and often fatal infection. These conditions are extremely difficult to diagnose in the absence of other indicators. Morphologic anomalies of peripheral blood erythrocytes, such as Howell-Jolly (HJ) bodies, may be the only evidence of the presence of a nonfunctional spleen .
Worldwide, most patients with asplenia or hyposplenia have an underlying hemoglobinopathy such as sickle cell disease.
Isolated asplenia and polysplenia are commonly associated with significant abnormalities involving other organ systems.
An awareness of these associations and syndromes may help in screening the patient for splenic dysfunction.
The most important clinical indication for the evaluation of splenic function is the presence of complex congenital heart disease. Patients should be evaluated for splenic dysfunction if any of the following are present:
Recurrent infection or sepsis, especially with encapsulated organisms
Family history of asplenia or polysplenia
Cyanotic congenital heart disease or complex cardiac malformations
Evidence of visceral heterotaxy or other associated malformations
Bilateral trilobed or bilobed lungs on chest radiographs
In contrast, the presentation of patients with isolated congenital absence or hypoplasia of the spleen may be less dramatic.
Children with these conditions may present to the primary caretaker with fever or overwhelming sepsis, or they may even be moribund.
Associated cardiovascular, pulmonary, gastrointestinal, or genitourinary abnormalities may not be present to alert the physician to their underlying immunocompromised state.
Features such as thrombocytosis, HJ bodies in red cells, and recurrent episodes of invasive infections with encapsulated organisms may be helpful in identifying individuals with isolated absence or hypoplasia of the spleen. The absence of these features, however, does not exclude splenic malfunction, although it may make the diagnosis more difficult.