We are sorry to hear of your emergency surgery.
A manipulator such as you describe is generally of a small enough diameter that introducing it into the uterus through the cervix is not considered an opening of the uterus that makes a woman niddah. The inflation within the uterus is not a factor here.
Additionally, since the procedure is likely to lead to some traumatic bleeding, bleeding following the procedure may be attributed to the trauma, and thus not be considered niddah bleeding.
In other words, based on what you write and our understanding of the procedure, it did not make you niddah. You may find it helpful at this stage to be careful with staining so as to avoid unnecessary questions. (Learn more about the relevant precautions in our articles on Staining and Toilet Paper.)
Please be in touch with any further questions.
We wish you a refuah sheleimah!