A slang term for a red blood cell transfusion made up of
'packed' red blood cells (PRBC). When donors give blood, the
blood bank concentrates the red blood cells in a small volume of
plasma. The excess plasma is saved for transfusion to those who
need plasma. The concentrated red blood cells are called
'packed' because they are in a more compressed volume of blood
than they were in the donor's blood. The above paragraph was
taken from www.babyzone.com This type of blood transfusion is
usually done to raise hematocrit levels in patients who are
deficient for one reason or another (like anemia).