What does the medical abbreviation ag mean?

Answer 1

Acute Gastroenteritis which means food poisoning! =D
Agarose Gel Electrophoresis is a method used in biochemistry and molecular Biology to separate DNA, RNA, or protein molecules by size. This is achieved by moving negatively charged nucleic acid molecules through an agarose matrix with an electric field (electrophoresis). Shorter molecules move faster and migrate further than longer ones.

or

Acute Gastroenteritis

Acute Gastroenteritis

Answer 2

Ag in medical terms most often refers to antigen, but it could refer to silver.