A natural miscarriage refers to the spontaneous expulsion of the gestational sac from within the uterine cavity, in contrast to a miscarriage induced through medical intervention. A natural miscarriage is not the same as a complete miscarriage, which occurs when the gestational sac is completely expelled from the uterus without any remnants. Whether a natural miscarriage is complete is typically determined about a week after the event by a follow-up ultrasound. If the uterine cavity has no remnants or only minimal fluid accumulation, the miscarriage is considered complete, and usually, no surgical cleaning of the uterus is required. However, if the ultrasound after a natural miscarriage reveals substantial remnants within the uterine cavity, this indicates an incomplete miscarriage, and surgical cleaning of the uterus is generally necessary.