From: Rabbi Moshe Sofer
To: Rabbi Lipman
A woman with uterine prolapse has a wax ring placed inside her womb that she cannot safely remove. The Chasam Sofer rules that if removal is truly impossible, the ring does not constitute a chatzitzah invalidating tevilah, since her inability to remove it renders her non-particular about it (miyut she'eino makpid), and its location in beis hastarim adds a further rabbinic leniency (terei derabanan). He partially disputes the Noda BiYehudah's reasoning, arguing that removal for childbirth does not reflect hakpada about the ring itself.
Source: Shu"t Chasam Sofer YD §192