A system for treating uterine tissue having a seal assembly configured for positioning in a patient's cervical canal and uterine cavity； an expandable distal balloon portion； an expandable elongate medial balloon portion configured for movement between a first transversely expanded shape for engaging a cervical canal and a second transversely non-expanded shape for trans-cervical insertion； and a fluid source in communication with distal balloon portion and medial balloon portion for expansion of said balloon portions.
