CONTRACEPTION
DO RRTROVRRTRD UTERI ADVERSELY AFFECT INSERTIONS AND PERFORWUKE
OF IUDS?
I-cheng Chi*, Gaston Farr, Rosalie Dominik and Nancy Robinson Family Health International, P.O. Box 13950, Research Triangle Park, NC 27709, USA ABSTRACT
A large international multi-center IUD data set (N=5520) coordinated by Family Health International was analysed to determine if the uterine position of a woman (anteverted, mid-positioned or retroverted) affects the ease of IUD insertion and if knowledge of uterine position would diminish insertion-related problems and improve IUD performance. Findings showed that insertion-related events were rare irrespective of uterine position. Women with retroverted uteri were not associated with higher termination rates for accidental pregnancy, expulsion or removal for bleeding and/or pain after 12 months of IUD use, as compared to the other two uterine position groups. All insertions in this data set were performed by experienced obstetricians/gynecologists,and our findings suggest that women with retroverted uteri should be equally good candidates for IUD contraception. * To whom correspondence should be addressed
Submitted for publication October 6, 1989 Accepted for publication January 22, 1990
MAY 199OVOL. 41 NO. 5
495
CONTRACEPTION INTRODUC!l'ION
Does the position of a woman's uterus affect the ease of insertion of an IUD? Would the knowledge of uterine position through pelvic examination facilitate IUD insertion, diminish insertion-related problems and improve IUD performance? An extensive literature search produced only one report focusing on these issues. The report, published in 1986 (1) by the United Kingdom IUD Research Network, presented the following findings: 1) fitting difficulty of an IUD was almost twice as frequent in women who had retroverted uteri, as compared to those with anteverted uteri; 2) the IUD expulsion rate was slightly higher among women when fitting difficulties had been reported and among women with retroverted or mid-positioned uteri. In addition, the investigators were "puzzled" with their finding of a lower pregnancy rate among women with reported fitting difficulties. We will answer the above-posed questions using the large international multi-center IUD dataset originally collected for clinical trials by Family Health International (FHI). METHODS AND MATERIALS Our analysis is limited to parous women who had copper IUDs inserted by obstetricians/gynecologistsat least 42 days after their last live birth ended. Women having anatomical uterine abnormalities (e.g., uterine fibroma/myoma) were excluded. The IUD types included for study were: the T-shaped copper devices (the TCu 200, TCu 380A or TCu 38OAG) and the horseshoe-shaped multiload devices (the MLCu 250 and MLCu 375). Centers meeting the following criteria were included in the analysis: 1) performed 50 or more insertions using one of the above study device types; 2) collected information on the uterine position for at least 90% of their cases; and 3) achieved a six-month follow-up rate of 80% or higher with their patients. A total of 5603 women came from centers which met the above criteria. The IUD insertions were performed between January 1977 and December 1987 at 23 international centers, all except one located in less developed countries (LDCs) by Sivard's definition (2). Excluded from the analyses were 83 (1.5%) women with no information on uterus position; 5520 women remained as our study population. We divided our study population into three uterine position groups based on the findings at pelvic examination by the insertors immediately before IUD insertion: anteverted (N=3135, 56.8%), mid-positioned (N=852, 15.4%) and retroverted (N=1533, 27.8%). The three groups of women were first compared on a number of characteristics including age, parity, educational level, desire for additional children, contraceptive method used within the month prior to this insertion, menstrual status and breast-feeding status at the time of IUD insertion, and the IUD type inserted at this admission. Comparisons were then performed on two sets of outcome variables: 1) the IUD insertion-related problems including insertion failure, uterine perforation, syncope and other vasovagal reactions, moderate/severe insertional pain, cervical laceration and cervical dilatation required for IUD insertion; and 2) subsequent IUD performance in terms of termination rates due to pregnancies, expulsions
496
MAY 1990 VOL. 41. NO. 5
CONTRACEPTION and removalsfor bleeding and/or pain, as well as the continuation rates at six and 12 months post-insertion. Because of the low incidence of insertion-related events, comparisons were performed by Fisher's exact test between women with either an anteverted or mid-positioned uterus collapsed as one group and women with retroverted uteri as another group. Cumulative gross life-table rates of the pertinent termination events were calculated by the Tietze-Potter method (3) and compared by the log-rank method (4). Women's characteristics which showed statistically significant differences among the three groups were considered confounding variables and were adjusted for, one at a time, using Herson's method (5). To determine whether our findings could be influenced by possible differences between centers, similar comparisons of IUD performance among the three uterine position groups were made on a sub-data set from one Asian center. For the 1290 insertions performed in this center, 1250 had information on uterine position (contributing 22.6% of the cases in our study population): 615 were using TCu 380A and 635, the MLCu 250. A p-value of CO.05 (two-tailed) was considered statistically significant for all tests of significance. RESULTS 1.
Selected characteristics of the women (Table I)
The mean parity of the three groups of women hovers around two. Compared to the other two groups, women in the retroverted group were younger and less educated. The proportion of women wanting no more children in the retroverted group was higher than those women in the mid-positioned group, but lower than those in the anteverted group. Women in the retroverted uterus group were less likely to have used oral contraceptives or the IUDs in the month prior to this insertion and were more likely to be amenorrheic and breast-feeding at the time of insertion, as compared to women in either the anteverted or mid-position group. The distribution of device types inserted at admission also differed among the three groups. All these differences were statistically significant (p cO.01) because of the relatively large numbers of cases in each uterine position group. The magnitude of the differences in age and parity were, however, considered not to be clinically important.
MAY 199OVOL. 41 NO. 5
497
CONTRACEPTION Table I. Characteristics of Women with Anteverted, Mid-positioned or Retroverted Uteri by Means and Percentage Distributions, the FHI International Multi-center IUD Data Set, 1977-1987 Uterus Position Characteristics of Women
Anteverted (N=3135)
Age in years (Mean+ SD) 27.1k5.4 Number live births (Mean+ SD) 2.1k1.4 Education in years (Mean? SD) 8.7k4.8 % Wanting no more children 53.0 % Contraceptive method used last month Orals 27.9 IUDs 9.0 Other or no methods 63.1 Menstrual status* Still amenorrheic 17.5 Menses resumed 82.5 Breast-feeding status Yes (including partial)31.9 No 68.1 % IUD Type inserted this time TCu 200 33.5 TCu 380A 21.2 TCu 380AG 17.4 MLCu 250 11.3 MLCu 375 16.6
Mid-positioned Retroverted (N=852) (N=1533)
26.9k5.7
26.5k5.4
2.0?1.6
2.Ok1.2
7.5k5.1
7.324.8
44.1
46.5
29.6
23.9 5.9
7.5 62.9
70.2
16.1 83.9
29.8 70.2
31.3 68.7
43.1 56.9
30.0 36.0 8.5 17.2 8.3
25.6 31.4 11.4 22.6 9.0
*Sixty women with unknown values in menstrual status were excluded from calculation of percentages.
MAY 1990 VOL. 41. NO. 5
CONTRACEPTION 2.
The insertion-related
events
(Table II)
A total of 10 insertion failures occurred, five in the anteverted group, two in the mid-positioned group and three in the retroverted uterus group. The incidence rates hovered around two per 1000 insertions. The
Table II. Number and Incidence of Insertion-related Events among Women with Anteverted, Mid-positioned or Retroverted Uteri, the FHL International Multi-center IUD Data Set, 1977-1987 Uterus Position
Insertion-related Events
Anteverted (N=3135) No.
Incidence
Mid-positioned (N=852)
Retroverted (N=1533)
No.
Incidence
No,
Incidence
2 1
2.4 1.2
3 0
2.0 0.0
20 (1)
2.4 (0.1)
26 (2)
Incidence per 1000 insertions Insertion failure* Uterine perforation
5 0
1.6 0.0
Incidence per 100 insertions Moderate and severe insertional pain 39 (Severe only) (0) Syncope & other vasovagal reactions 6 Cervical laceration**44 Cervical dilatation 43
0.2 1.4 1.4
0 24 a
0.0 2.8 0.9
4 15 15
0.3 1.0 1.0
* For calculation of incidences for all other insertion-related events, insertion failures were excluded from numerators and denominators. **The difference between women with anteverted uteri and the other two groups of women is statistically significant at
DO RRTROVRRTRD UTERI ADVERSELY AFFECT INSERTIONS AND PERFORWUKE
OF IUDS?
I-cheng Chi*, Gaston Farr, Rosalie Dominik and Nancy Robinson Family Health International, P.O. Box 13950, Research Triangle Park, NC 27709, USA ABSTRACT
A large international multi-center IUD data set (N=5520) coordinated by Family Health International was analysed to determine if the uterine position of a woman (anteverted, mid-positioned or retroverted) affects the ease of IUD insertion and if knowledge of uterine position would diminish insertion-related problems and improve IUD performance. Findings showed that insertion-related events were rare irrespective of uterine position. Women with retroverted uteri were not associated with higher termination rates for accidental pregnancy, expulsion or removal for bleeding and/or pain after 12 months of IUD use, as compared to the other two uterine position groups. All insertions in this data set were performed by experienced obstetricians/gynecologists,and our findings suggest that women with retroverted uteri should be equally good candidates for IUD contraception. * To whom correspondence should be addressed
Submitted for publication October 6, 1989 Accepted for publication January 22, 1990
MAY 199OVOL. 41 NO. 5
495
CONTRACEPTION INTRODUC!l'ION
Does the position of a woman's uterus affect the ease of insertion of an IUD? Would the knowledge of uterine position through pelvic examination facilitate IUD insertion, diminish insertion-related problems and improve IUD performance? An extensive literature search produced only one report focusing on these issues. The report, published in 1986 (1) by the United Kingdom IUD Research Network, presented the following findings: 1) fitting difficulty of an IUD was almost twice as frequent in women who had retroverted uteri, as compared to those with anteverted uteri; 2) the IUD expulsion rate was slightly higher among women when fitting difficulties had been reported and among women with retroverted or mid-positioned uteri. In addition, the investigators were "puzzled" with their finding of a lower pregnancy rate among women with reported fitting difficulties. We will answer the above-posed questions using the large international multi-center IUD dataset originally collected for clinical trials by Family Health International (FHI). METHODS AND MATERIALS Our analysis is limited to parous women who had copper IUDs inserted by obstetricians/gynecologistsat least 42 days after their last live birth ended. Women having anatomical uterine abnormalities (e.g., uterine fibroma/myoma) were excluded. The IUD types included for study were: the T-shaped copper devices (the TCu 200, TCu 380A or TCu 38OAG) and the horseshoe-shaped multiload devices (the MLCu 250 and MLCu 375). Centers meeting the following criteria were included in the analysis: 1) performed 50 or more insertions using one of the above study device types; 2) collected information on the uterine position for at least 90% of their cases; and 3) achieved a six-month follow-up rate of 80% or higher with their patients. A total of 5603 women came from centers which met the above criteria. The IUD insertions were performed between January 1977 and December 1987 at 23 international centers, all except one located in less developed countries (LDCs) by Sivard's definition (2). Excluded from the analyses were 83 (1.5%) women with no information on uterus position; 5520 women remained as our study population. We divided our study population into three uterine position groups based on the findings at pelvic examination by the insertors immediately before IUD insertion: anteverted (N=3135, 56.8%), mid-positioned (N=852, 15.4%) and retroverted (N=1533, 27.8%). The three groups of women were first compared on a number of characteristics including age, parity, educational level, desire for additional children, contraceptive method used within the month prior to this insertion, menstrual status and breast-feeding status at the time of IUD insertion, and the IUD type inserted at this admission. Comparisons were then performed on two sets of outcome variables: 1) the IUD insertion-related problems including insertion failure, uterine perforation, syncope and other vasovagal reactions, moderate/severe insertional pain, cervical laceration and cervical dilatation required for IUD insertion; and 2) subsequent IUD performance in terms of termination rates due to pregnancies, expulsions
496
MAY 1990 VOL. 41. NO. 5
CONTRACEPTION and removalsfor bleeding and/or pain, as well as the continuation rates at six and 12 months post-insertion. Because of the low incidence of insertion-related events, comparisons were performed by Fisher's exact test between women with either an anteverted or mid-positioned uterus collapsed as one group and women with retroverted uteri as another group. Cumulative gross life-table rates of the pertinent termination events were calculated by the Tietze-Potter method (3) and compared by the log-rank method (4). Women's characteristics which showed statistically significant differences among the three groups were considered confounding variables and were adjusted for, one at a time, using Herson's method (5). To determine whether our findings could be influenced by possible differences between centers, similar comparisons of IUD performance among the three uterine position groups were made on a sub-data set from one Asian center. For the 1290 insertions performed in this center, 1250 had information on uterine position (contributing 22.6% of the cases in our study population): 615 were using TCu 380A and 635, the MLCu 250. A p-value of CO.05 (two-tailed) was considered statistically significant for all tests of significance. RESULTS 1.
Selected characteristics of the women (Table I)
The mean parity of the three groups of women hovers around two. Compared to the other two groups, women in the retroverted group were younger and less educated. The proportion of women wanting no more children in the retroverted group was higher than those women in the mid-positioned group, but lower than those in the anteverted group. Women in the retroverted uterus group were less likely to have used oral contraceptives or the IUDs in the month prior to this insertion and were more likely to be amenorrheic and breast-feeding at the time of insertion, as compared to women in either the anteverted or mid-position group. The distribution of device types inserted at admission also differed among the three groups. All these differences were statistically significant (p cO.01) because of the relatively large numbers of cases in each uterine position group. The magnitude of the differences in age and parity were, however, considered not to be clinically important.
MAY 199OVOL. 41 NO. 5
497
CONTRACEPTION Table I. Characteristics of Women with Anteverted, Mid-positioned or Retroverted Uteri by Means and Percentage Distributions, the FHI International Multi-center IUD Data Set, 1977-1987 Uterus Position Characteristics of Women
Anteverted (N=3135)
Age in years (Mean+ SD) 27.1k5.4 Number live births (Mean+ SD) 2.1k1.4 Education in years (Mean? SD) 8.7k4.8 % Wanting no more children 53.0 % Contraceptive method used last month Orals 27.9 IUDs 9.0 Other or no methods 63.1 Menstrual status* Still amenorrheic 17.5 Menses resumed 82.5 Breast-feeding status Yes (including partial)31.9 No 68.1 % IUD Type inserted this time TCu 200 33.5 TCu 380A 21.2 TCu 380AG 17.4 MLCu 250 11.3 MLCu 375 16.6
Mid-positioned Retroverted (N=852) (N=1533)
26.9k5.7
26.5k5.4
2.0?1.6
2.Ok1.2
7.5k5.1
7.324.8
44.1
46.5
29.6
23.9 5.9
7.5 62.9
70.2
16.1 83.9
29.8 70.2
31.3 68.7
43.1 56.9
30.0 36.0 8.5 17.2 8.3
25.6 31.4 11.4 22.6 9.0
*Sixty women with unknown values in menstrual status were excluded from calculation of percentages.
MAY 1990 VOL. 41. NO. 5
CONTRACEPTION 2.
The insertion-related
events
(Table II)
A total of 10 insertion failures occurred, five in the anteverted group, two in the mid-positioned group and three in the retroverted uterus group. The incidence rates hovered around two per 1000 insertions. The
Table II. Number and Incidence of Insertion-related Events among Women with Anteverted, Mid-positioned or Retroverted Uteri, the FHL International Multi-center IUD Data Set, 1977-1987 Uterus Position
Insertion-related Events
Anteverted (N=3135) No.
Incidence
Mid-positioned (N=852)
Retroverted (N=1533)
No.
Incidence
No,
Incidence
2 1
2.4 1.2
3 0
2.0 0.0
20 (1)
2.4 (0.1)
26 (2)
Incidence per 1000 insertions Insertion failure* Uterine perforation
5 0
1.6 0.0
Incidence per 100 insertions Moderate and severe insertional pain 39 (Severe only) (0) Syncope & other vasovagal reactions 6 Cervical laceration**44 Cervical dilatation 43
0.2 1.4 1.4
0 24 a
0.0 2.8 0.9
4 15 15
0.3 1.0 1.0
* For calculation of incidences for all other insertion-related events, insertion failures were excluded from numerators and denominators. **The difference between women with anteverted uteri and the other two groups of women is statistically significant at
