Sickle Cell Disease Spleen Complications
Normally, flexible and smooth red blood cells pass swiftly through the spleen. The spleen receives about 3 to 5% of the total blood volume per minute.
In most older children and adults with HbSS disease, repeated sickling in the spleen and local infarction (tissue death) eventually results in scarring, fibrosis, and a non-functional spleen (called functional asplenia or auto splenectomy). In infants and young children (up to age 5-6 years), the spleen may be enlarged or congested (filled with blood).
Major Splenic Sequestration
Splenic sequestration (blood trapped in the spleen) refers to a sudden condition of pooling of large amounts of blood in the spleen. Children with sickle cell disease between ages five months and two years represent most cases of splenic sequestration.
During severe sequestration crisis, the blood-filled spleen may enlarge to the point of filling the entire abdomen. The child’s hemoglobin may drop rapidly (to as low as 1-3g/dl) resulting in hypovolemic shock (low level of blood in the circulation results in lack of blood to all organs) and death within hours.
Quick treatment with blood volume expanders and blood transfusion to reverse the hypovolemic shock can support the body until the blood trapped in the spleen return to the normal circulation.
Minor Splenic Sequestration
Minor sequestration events are common in young children with sickle cell disease. Some cases can happen with viral illnesses. Mild episodes can cause an enlarged spleen and blood changes such as worsened anemia (low hemoglobin) often a 1-3g/dl decrease from the patient’s baseline hemoglobin, or thrombocytopenia (low platelet count).
Due to overall less sickle-related infarction, the spleens of patients with HbSC or HbSβ+thalassemia may remain enlarged (persistent splenomegaly) or retain the ability to enlarge into adulthood. Therefore, they are also at risk for sequestration.
Because sequestration tends to recur and because of the sudden onset of this life-threatening condition, splenectomy (removal of the spleen) should be considered if the child has had more than one episode.