Surgery

Surgery was any procedure performed on a patient often resulting in opening or closing of the body; it was usually performed with the hope of improving the health of the person operated on. It was commonly performed by a surgeon.

Cosmetic surgery was one type used to make one species look like another. 

Exploratory surgery was often used by a doctor to assist in diagnosing a patient, such as by Dr. Bashir when he attempted to determine the cause of the sudden generosity of the Grand Nagus. 

Microsurgery often involved a microscope, typically operating on an area of approximately one millimeter in diameter. Microsurgery was often the least invasive form of surgery.