Yesterday I finally got around to posting my followup over there and now I'm posting the part that is relevant to menstrual cups below. To see the post in it's entirety, click HERE.
Does using internal period protection increase the risk of expulsion?
Based on the answers to Poll #1363283, this would also seem to be an exaggerated fear.
With 121 divas who currently use an IUD or have used one within the last 5 years responding, 64% (77 women) reported that they use some form of internal period protection.
Of these 77 women, 56 use tampons (73%), 24 use menstrual cups (31%), 1 person reported using sponges, and 1 reported "other" (baby sock tampons?)
Out of the 77 divas who reported using tampons, cups, or sponges, the vast majority, 78% (60 women), began using internal protection within the first month of having an IUD inserted. Of those 60, more than half (33 women) have successfully had their IUD in place for at least 6 months.
Out of 121 who currently use an IUD or have used one within the last 5 years, only 5 reported an "on period expulsion". Three reported using pads (1 cloth, 2 disposable) , 1 used a menstrual cup, and 1 used a combination of tampons and sponges. Simply looking at the numbers for this poll, this puts the expulsion rate for pad users at 7%, menstrual cup users at 4% and tampons/sponges users at 2%... As such, I believe it is unlikely that choice of period protection influences IUD expulsion.
The menstrual cup user had her IUD in place for less than 2 weeks before expelling, and while she credits her cup for helping to pull out her IUD, here she cites long strings as a contributing factor.
As mentioned earlier, the tampon/sponge user accidentally yanked out her 5 year old Paragard thinking she had a tampon in... read her story here.
While the results here suggest that using internal protection does not increase expulsion risk, it is still probably wise to use caution when removing a tampon, cup, or sponge.