Intrauterine Contraception: Factors Associated With Uterine Perforation
Intrauterine Contraception: Factors Associated With Uterine Perforation
Before initiation of the study, the Ethics Committees of the Hospital of Helsinki and Uusimaa as well as the hospital district of Helsinki and Uusimaa gave positive statements regarding the project. The Ministry of Social Affairs and Health and the National Institute for Health and Welfare gave permission to use the register and medical record data in the research.
The present data were taken from the National Care Register for Finnish Health Institutions, later called the Hospital Register. The register contains ICD-10 (International Classification of Diseases, 2010) and operation codes on all patients treated at Finnish hospitals. As there is no specific ICD-10 code for IUD/IUS perforation, subjects with potential uterine perforation were identified from the Hospital Register by using the operation codes of the Nordic Medico-Statistical Committees (NOMESCO) Classification of Surgical Procedures, available since 1997, for removal of an intra-abdominal or intrauterine foreign object (JAL10-11, JAL-20-22) combined with the ICD-10 codes implementing gynaecological procedures relating to IUD/IUS complications (T83.3, T19.3), insertion and follow-up (Z30). As ICD-10 was introduced in Finland in 1996, subjects treated from 1 January 1996 through 31 December 2009 were included in the present analysis. Patient selection is shown in Fig. 1. Combining these diagnostic and operation codes resulted in the identification of 3909 patients. By excluding codes unrelated to possible perforation and male patients, 370 patients with probable surgically treated uterine perforation were found nationwide. Records of 108 patients treated at the clinics of the hospital district of Helsinki and Uusimaa were examined by J.K., resulting in identification of 78 patients with surgically treated uterine perforations and 30 patients treated for other IUD/IUS-related reasons. Of the patients with perforation, 10 were excluded as the device had been inserted prior to the beginning of the study period, leaving 68 patients included in the study. The distribution of the type of surgically removed devices is shown in Fig. 2.
(Enlarge Image)
Figure 1.
Flow chart of the study patients.
(Enlarge Image)
Figure 2.
Surgical removal of perforating IUDs/IUSs (n = 68) by year of insertion in the hospital district of Helsinki and Uusimaa from 1996 to 2009, shown for the Cu-IUD and the LNG-IUS.
The number of IUDs/IUSs sold by a major pharmaceutical company (Bayer Ag, Berlin, Germany) during the corresponding time period was used to represent the number of Cu-IUDs (NovaT®) and LNG-IUSs (Mirena®) inserted during the study period. These two devices account for more than 90% of nationally sold devices during the study period. The number of devices sold in the area of Helsinki and Uusimaa accounts for ~29% of nationally sold devices. Precise sales numbers for the Helsinki and Uusimaa area are known for the LNG-IUS starting from 1997 and for the Cu-IUD starting from 2004. Numbers prior to this are estimated to be 33% for the LNG-IUS and 25% for the Cu-IUD of all nationally sold devices according to the known ratio during recent years.
The annual number of IUDs/IUSs sold within the area of the hospital district of Helsinki and Uusimaa varied from 8800 to 13 848 (mean 11 712) during the study period; Cu-IUD sales numbers decreased from 9100 to 1642 and those of the LNG-IUS increased from 2700 to 12 029 annually. The proportion of LNG-IUS sales rapidly increased to half of all sold IUDs in only 5 years since its introduction in 1990, starting from 19% during its first year and presently accounting for 85–88% of sold devices.
All data used in the study derives from hospital records containing the referral for examination and treatment, background information of the patient as well as reports on findings and treatment. As the data were retrospectively collected, some of the data of interest were missing.
Data analysis was performed by using Predictive Analysis Software, PASW18 (SPSS Inc., Chicago, IL, USA). Concerning missing data, the statistical calculations were performed among those women with known status only. The incidence of surgically treated IUD/IUS perforation was calculated by comparing the above-mentioned sales figures with the number of surgically treated patients. Subjects were analysed both as one group and as separate groups by type of device, LNG-IUS versus Cu-IUD, using Mann–Whitney and chi-square tests as appropriate. Statistical significance was set at P ≤ 0.05.
Materials and Methods
Before initiation of the study, the Ethics Committees of the Hospital of Helsinki and Uusimaa as well as the hospital district of Helsinki and Uusimaa gave positive statements regarding the project. The Ministry of Social Affairs and Health and the National Institute for Health and Welfare gave permission to use the register and medical record data in the research.
The present data were taken from the National Care Register for Finnish Health Institutions, later called the Hospital Register. The register contains ICD-10 (International Classification of Diseases, 2010) and operation codes on all patients treated at Finnish hospitals. As there is no specific ICD-10 code for IUD/IUS perforation, subjects with potential uterine perforation were identified from the Hospital Register by using the operation codes of the Nordic Medico-Statistical Committees (NOMESCO) Classification of Surgical Procedures, available since 1997, for removal of an intra-abdominal or intrauterine foreign object (JAL10-11, JAL-20-22) combined with the ICD-10 codes implementing gynaecological procedures relating to IUD/IUS complications (T83.3, T19.3), insertion and follow-up (Z30). As ICD-10 was introduced in Finland in 1996, subjects treated from 1 January 1996 through 31 December 2009 were included in the present analysis. Patient selection is shown in Fig. 1. Combining these diagnostic and operation codes resulted in the identification of 3909 patients. By excluding codes unrelated to possible perforation and male patients, 370 patients with probable surgically treated uterine perforation were found nationwide. Records of 108 patients treated at the clinics of the hospital district of Helsinki and Uusimaa were examined by J.K., resulting in identification of 78 patients with surgically treated uterine perforations and 30 patients treated for other IUD/IUS-related reasons. Of the patients with perforation, 10 were excluded as the device had been inserted prior to the beginning of the study period, leaving 68 patients included in the study. The distribution of the type of surgically removed devices is shown in Fig. 2.
(Enlarge Image)
Figure 1.
Flow chart of the study patients.
(Enlarge Image)
Figure 2.
Surgical removal of perforating IUDs/IUSs (n = 68) by year of insertion in the hospital district of Helsinki and Uusimaa from 1996 to 2009, shown for the Cu-IUD and the LNG-IUS.
The number of IUDs/IUSs sold by a major pharmaceutical company (Bayer Ag, Berlin, Germany) during the corresponding time period was used to represent the number of Cu-IUDs (NovaT®) and LNG-IUSs (Mirena®) inserted during the study period. These two devices account for more than 90% of nationally sold devices during the study period. The number of devices sold in the area of Helsinki and Uusimaa accounts for ~29% of nationally sold devices. Precise sales numbers for the Helsinki and Uusimaa area are known for the LNG-IUS starting from 1997 and for the Cu-IUD starting from 2004. Numbers prior to this are estimated to be 33% for the LNG-IUS and 25% for the Cu-IUD of all nationally sold devices according to the known ratio during recent years.
The annual number of IUDs/IUSs sold within the area of the hospital district of Helsinki and Uusimaa varied from 8800 to 13 848 (mean 11 712) during the study period; Cu-IUD sales numbers decreased from 9100 to 1642 and those of the LNG-IUS increased from 2700 to 12 029 annually. The proportion of LNG-IUS sales rapidly increased to half of all sold IUDs in only 5 years since its introduction in 1990, starting from 19% during its first year and presently accounting for 85–88% of sold devices.
All data used in the study derives from hospital records containing the referral for examination and treatment, background information of the patient as well as reports on findings and treatment. As the data were retrospectively collected, some of the data of interest were missing.
Data analysis was performed by using Predictive Analysis Software, PASW18 (SPSS Inc., Chicago, IL, USA). Concerning missing data, the statistical calculations were performed among those women with known status only. The incidence of surgically treated IUD/IUS perforation was calculated by comparing the above-mentioned sales figures with the number of surgically treated patients. Subjects were analysed both as one group and as separate groups by type of device, LNG-IUS versus Cu-IUD, using Mann–Whitney and chi-square tests as appropriate. Statistical significance was set at P ≤ 0.05.