A Sonohysterogram is an extension of a transvaginal examination, usually for problems relating to the endometrial lining of the womb.
It involves a procedure similar to a pap smear in which the doctor will pass a very fine plastic tube into the cervix. The speculum is then taken out of the vagina and a transvaginal scan is started. A small amount of a warm saline solution is passed through the tube into the womb. This separates the internal wall of the womb slightly, to highlight polyps and fibroids which may be growing into the space inside the womb. It is also a good way of identifying unusual womb shapes that can increase the risks of miscarriage and pregnancy complications.