Pathology

Pathology is the study and medical diagnosis of disease, especially after death. A person who does this work is called a pathologist. Techniques include dissection, microscopic examination of tissues and chemical analysis of fluids. A pathologist may perform an autopsy, to discover the cause of death. 
Pathology is a science that concerns with finding the cause (etiology) or presence of a disease by careful examination of a tissue or sample of any component of the body by scrutinizing it.
Pathologists often work with biochemists in hospital laboratories.