An exchange transfusion requires that the patient's blood can be removed and replaced. In most cases, this involves placing one or more thin tubes, called catheters, into a blood vessel. The exchange transfusion is done in cycles, each one usually lasts a few minutes.

The patient's blood is slowly withdrawn (usually about 5 to 20 mL at a time, depending on the patient's size and the severity of illness). An equal amount of fresh, prewarmed blood or plasma flows into the patient's body. This cycle is repeated until the correct volume of blood has been replaced.

After the exchange transfusion, catheters may be left in place in case the procedure needs to be repeated.

In diseases such as sickle cell anemia, blood is removed and replaced with donor blood.

In conditions such as neonatal polycythemia , a specific amount of the child's blood is removed and replaced with a normal saline solution, plasma, or albumin (the clear liquid portion of blood). This decreases the total number of red blood cells in the body and makes it easier for blood to flow through the body.

An exchange transfusion may be needed to treat the following conditions:

• Neonatal polycythemia
• Rh-induced hemolytic disease of the newborn
• Severe disturbances in body chemistry
• Severe newborn jaundice that does not respond to phototherapy with bili lights
• Severe sickle cell crisis
• Toxic effects of certain drugs

General risks are the same as with any transfusion. Other possible complications include:

• Blood clots
• Changes in blood chemistry (high or low potassium, low calcium, low glucose, change in acid-base balance in the blood )
• Heart and lung problems
• Infection (greatly decreased risk due to careful screening of blood)
• Shock due to inadequate replacement of blood

The infant may need to be monitored for several days in the hospital after the transfusion, but the length of stay generally depends on the condition for which the exchange transfusion was performed.