Fluids with low protein concentrations and low cellularity that are usually secondary to congestive heart failure or in animals with low blood albumin concentrations.

Cytology is the exam of a single cell type, as often found in fluid specimens. It's mainly used to diagnose or screen for cancer. It's also used to screen for fetal abnormalities, for pap smears, to diagnose infectious organisms, and in other screening and diagnostic areas."