Cytological screening
A cytological screening was an analysis of the s of the body, sometimes used to determine blood type and donor compatibility. 

In 2371, The Doctor was required to do a complete pyrocyte replacement to the sole survivor of a Kazon raider in order to keep him alive. In preparation of the procedure, Kes offered to run a cytological screening of 's crew in order to find a compatible donor. ()

de:Cytologische Analyse
Medical procedures