A pathologist is a scientist in the medical or biological field who studies the causes, nature, and effects of disease in both plant and animal life forms. The field of pathology is broad with concentrations on changes in cells, tissues, and organs that are the result of a disease.
A Pathologist could:
Examine kidney tissues of a patient under a microscope to determine if the patient is in need of a transplant.
Perform an autopsy to decide if the person died of homicide or natural causes. This information could be used to help solve a crime.
Look over the blood test of a pregnant woman to determine if the child she is carrying will be born in good health.