I am not a ob/gyn nurse either, but I would imagine the biggies would be risk for perforation, and risk for infection.
Like the last poster said, a regular D&C is blind anything can happen. Nothing is worse than DUB, and it seems a lot of nurses suffer from it. However, there are alot of causes behind it. Everything from endocrine disorders to polyps, obesity to uterine ca.
Obviously, if the patient's bleeding is that severe to require transfusions, she may have been told in the past that she would require a hysterectomy-perhaps she isn't ready yet.