Washed red blood cells are prepared by washing red cells with what solution?

Washed red blood cells are typically prepared by washing them with normal saline. This isotonic solution helps to maintain the integrity of the red blood cells and prevents hemolysis during the washing process. Normal saline, which contains 0.9% sodium chloride, is compatible with the osmotic needs of the red blood cells; it keeps them in a stable state while removing plasma proteins, leukocytes, and any residual anticoagulants.

Using distilled water, for example, would lead to the destruction of red blood cells, as it is hypotonic and could cause them to swell and burst. Physiological saline could refer to a similar concentration, but it's less commonly used than the specifically defined normal saline in this context. Isotonic dextrose solution is also not suitable for washing red blood cells, as the presence of glucose could lead to metabolic changes that affect the viability of the cells.

Thus, normal saline is the appropriate choice for preparing washed red blood cells due to its compatibility and safety with red blood cell maintenance.