Menstrual characteristics and ultrasonographic uterine cavity measurements predict bleeding and pain in nulligravid women using intrauterine contraception.Hum Reprod 2015; 30(7):1580-8HR
Is small uterine cavity size as assessed by ultrasonography associated with bleeding problems or pain in nulligravid women using intrauterine contraception, or do other factors affect these parameters?
Among levonorgestrel intrauterine system (LNG-IUS) users, small uterine cavity size is not associated with worsened clinical outcome, but is beneficial as women with the smallest cavity measurements were frequently amenorrhoeic and painless at the end of the first year but among copper intrauterine device (IUD) users, no associations between uterine cavity dimensions and clinical outcome were found.
WHAT IS KNOWN ALREADY
Nulligravid and nulliparous women have smaller uterine dimensions than parous women. Previously, many studies have revealed increased discontinuation rates of IUD use as a result of bleeding, pain or expulsion in these women, while recent studies with current models of IUS/IUDs indicate similar continuation and satisfaction rates irrespective of parity.
STUDY DESIGN, SIZE, DURATION
In a pilot study, 165 adult nulligravid women requesting their first IUD between 1 January 2011 and 31 July 2012 were given a free choice between two IUDs with equal frames measuring 32 × 32 mm-the LNG-IUS 52 mg or a copper-releasing IUD. The women were followed for 1 year.
PARTICIPANTS/MATERIAL, SETTING, METHODS
The LNG-IUS was chosen by 113 women (68.5%) and the copper IUD by 52 (31.5%). Prior to insertion the women were interviewed concerning their menstrual characteristics and uterine cavity size was measured by 2-D ultrasonography. After insertion the women kept daily records of bleeding and pain for two reference periods of 90 days during the first year (Months 1-3 and 10-12). The correlation between uterine cavity measurements and numbers of days of bleeding/spotting and pain during the reference periods was analysed. Continuation rates were assessed and reasons for discontinuation as well as the effects of baseline participant characteristics on outcomes were analysed in regression models.
MAIN RESULTS AND THE ROLE OF CHANCE
Both uterine cavity size and baseline menstrual characteristics prior to IUD insertion predicted the numbers of days of bleeding/spotting and pain in LNG-IUS users. Women with small uterine cavity dimensions reported less bleeding/spotting in both reference periods and less pain in the second reference period compared with women with larger dimensions. Baseline scanty spontaneous menstrual bleeding prior to LNG-IUS use (OR 9.4, 95% CI 1.7-51.8, P = 0.01) and smoking (OR 7.8, 95% CI 1.8-33.8, P = 0.006) predicted amenorrhoea in the second reference period. Women with baseline dysmenorrhoea reported more pain with both IUDs. Continuation rates and reasons for discontinuation were similar with both IUDs.
LIMITATIONS, REASONS FOR CAUTION
No sample size could be calculated to estimate the power as this was a pilot study. As the majority of women chose the LNG-IUS we did not achieve our initial aim of equally sized IUD groups and thus the size of the copper IUD group may have been insufficient to detect differences.
WIDER IMPLICATIONS OF THE FINDINGS
These data further encourage promotion of intrauterine contraception among nulligravid women. Routine use of ultrasonography to assess uterine cavity dimensions prior to IUD insertion is not indicated.
STUDY FUNDING/COMPETING INTERESTS
Supported by Helsinki University Central Hospital research funds, the Swedish Cultural Foundation in Finland and Finska Läkaresällskapet, who provided funds for J.K. O.H. serves on advisory boards for Bayer Healthcare, Gedeon Richter and MSD Finland (part of Merck & Co. Inc.) and has designed educational events with these companies. S.S. has lectured in educational events at Bayer and MSD Finland (part of Merck & Co. Inc.) and is a member of the Advisory Board for Contraception at MSD Finland. The other authors have no conflicts of interest to declare.
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