From: Rabbi Moshe Sofer
To: Rabbi Avraham
When a woman suffers from uterine prolapse and experiences no true hargashah — even if she feels moisture flow — one who rules leniently has substantial grounds to rely upon, since the blood does not emerge in the normal manner. However, this leniency applies only while the uterus remains displaced; once returned to its normal position, there is no basis for leniency.
Source: Shu"t Chasam Sofer YD §171