Uterine geometry and IUD-induced pain.

Sixty women using IUDs were included in two equal groups in the present study. Group I consisted of women presenting with pelvic pain for which they requested removal of the IUD, while the comparison group (group II) requested removal of the IUD for non-medical reasons. After extraction of the IUD, the Wing Sound II device was used to measure uterine cavity length and fundal transverse diameter. The uterine cavity measurements in both groups were not significantly different. When the ratios of IUD dimensions to uterine cavity measurements were compared, it was also found that there were no significant differences between groups. Factors other than discrepancies in size probably contribute to the pathogenesis of IUD-induced pain.