After a blood transfusion, healthcare providers watch you closely for any negative reactions.

A blood transfusion lowers the amount of hemoglobin S red blood cells in the body. When there are fewer sickled hemoglobin S cells in the bloodstream, they are less likely to build up and block blood vessels.

Blood transfusion also increases the number of normal red blood cells in the body, increasing the supply of oxygen to the body.

Anemia

Some sudden complications of sickle cell disease cause the body's red blood cell count to drop to life-threatening levels (severe anemia). When severe, these conditions (including splenic sequestration, acute chest syndrome, and aplastic crisis) can be fatal if not treated with blood transfusions.

Chronic severe anemia from kidney failure may need treatment with periodic blood transfusions.

Surgery

After having general anesthesia and surgery, people who have sickle cell disease are at risk for sickling-related problems and acute chest syndrome. Blood transfusions before surgery can prevent or treat these complications.

Red blood cell sickling-related complications (vaso-occlusion)

Blood transfusions can treat acute chest syndrome and leg ulcers.

Frequent blood transfusions may help prevent strokes in children who already had a stroke or are at high risk for a first stroke.^{footnote 1}