Life of a Pint

This is what a pint (unit) of blood looks like after donation. 

The first step in creating components from this pint involves a centrifuge.

The centrifuge separates the pint of blood into red blood cells and platelet-rich plasma.

This separated pint is then placed in an expresser that squeezes the platelet-rich plasma into another bag.

A preservative called Optisol is added to the red blood cells and the unit is stored in a refrigerator for up to 42 days.

The platelet-rich plasma is spun again in the centrifuge to separate the two components.

The centrifuged platelet-rich plasma is placed back into the expresser to squeeze the platelets into another bag.

Platelets are either pooled with other donors (above, left) or kept separated as single units, depending on hospital needs.

Platelets must be kept at room temperature and agitated constantly to remain viable. A unit of platelets lasts only 5 days.

The remaining component, plasma (above, right), is frozen and can keep for up to a year.

Each unit must undergo 14 separate tests to make sure it is safe for patients before leaving Michigan Blood.