Apheresis (ἀφαίρεσις (aphairesis, "a taking away")) is a medical technology in which the blood of a person is passed through an apparatus that separates out one particular constituent and returns the remainder to the circulation.

[citation needed] Intermittent flow centrifugation (IFC) works in cycles, taking blood, spinning/processing it and then giving back the unused parts to the donor in a bolus.

It does require a larger extracorporeal volume, and takes significantly longer to perform the procedure via IFC.

The first is spin speed and bowl diameter, the second is "sit time" in centrifuge, the third is solutes added, and the fourth is not as easily controllable: plasma volume and cellular content of the donor.

The result in most cases is the classic sedimented blood sample with the RBCs at the bottom, the buffy coat of platelets and WBCs (lymphocytes, granulocytes, monocytes) in the middle and the plasma on top.

For double red cell apheresis, donors of either gender require a minimum hemoglobin level of 14.0 g/dl.

It is therefore only employed if other means to control a particular disease have failed, or the symptoms are of such a nature that waiting for medication to become effective would cause suffering or risk of complications.

For autoimmune diseases in which apheresis is effective, it is used not as a standalone treatment, but rather in conjunction with therapies that reduce production of autoantibodies.

Routine use of fresh frozen plasma (FFP) is not generally appropriate because of the dangers including citrate toxicity (from the anticoagulant), ABO incompatibility, infection, and allergic reactions.