Most Obstetrician/Gynecologists (Ob/Gyns) complete a residency in this specialty and then go on to practice—delivering babies, seeing patients in their office, performing well-woman exams and performing operations like hysterectomies (removal of the uterus) and removal of ovarian cysts. However, an Ob/Gyn can go on to do more training after their residency in what is called a fellowship so that they sub-specialize. Below are the four sub-specialties of Ob/Gyn.