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ORIGINAL ARTICLE Fertility control

Intrauterine contraception: incidence

and factors associated with uterine

perforationa population-based study

Janina Kaislasuo1, Satu Suhonen2, Mika Gissler3,4, Pekka Lahteenmaki1,

and Oskari Heikinheimo1,*1Department of Obstetrics and Gynaecology, University of Helsinki and Helsinki University Central Hospital, PO Box 610, SF-00029 HUS,

Helsinki, Finland 2City of Helsinki Health Centre, Unit for Maternal and Child Health Care and Health Promotion, PO Box 6440, 00099

Helsinki, Finland 3National Institute for Health and Welfare, PO Box 30, 00271 Helsinki, Finland 4Nordic School of Public Health, Nya Varvet,

Gothenburg, Sweden

*Correspondence address. Department of Obstetrics and Gynaecology/Katiloopisto Hospital, Helsinki University Central Hospital, PO Box

610, 00029 HUS, Helsinki, Finland. Tel: +358-50-4271533; E-mail: [email protected]; [email protected]

Submitted on February 13, 2012; resubmitted on May 27, 2012; accepted on June 1, 2012

study question: What are the incidence and factors associated with uterine perforation by modern copper intrauterine device

(Cu-IUD) and the levonorgestrel-releasing intrauterine system (LNG-IUS)?

summary answer: Perforation incidence was similar to that reported in prior studies and did not vary between Cu-IUD and LNG-

IUS groups. Lactation, amenorrhoea and a post-partum period of ,6 months were common.

what is known and what this paper adds: The study supports findings in prior studies. The incidence rate was low and

factors associated with uterine perforation were similar to those in earlier reports.

design and data collection method: This retrospective population-based registry study included 68 patients surgically

treated for uterine perforation by an intrauterine device (IUD)/intrauterine system (IUS) at clinics in the Helsinki and Uusimaa hospital dis-

trict.

participants and setting: Records of 108 patients with probable uterine perforation by an IUD/IUS were analysed, leaving 68

patients treated for uterine perforation.

recruitment/sampling strategy: Patients with diagnostic and surgical treatment codes indicating uterine perforation by an

IUD/IUS between 1996 and 2009 were retrospectively selected from the Finnish National Hospital Register.

data analysis method: Patients with Cu-IUDs (n 17) and the LNG-IUS (n 51) were analysed as one group and also com-

pared using Mann Whitney and chi-square tests. IUD/IUS sales numbers were used to calculate incidences.

main findings: The overall incidence of perforation was 0.4/1000 sold devices, varying annually from 0 to 1.2/1000. The proportion

of both sold and perforating LNG-IUSs increased during the study period, but perforation incidence was not affected. Demographic char-

acteristics in the Cu-IUD and LNG-IUS groups were similar. More than half of the devices (55%) were inserted at ,6 months post-partum.

Breastfeeding at the time of insertion was common, comprising 32% of all patients. Moreover, of the breastfeeding women, 90% had deliv-

ered within 6 month prior to insertion.

implications: The population-based study setting represents a good overview of patients experiencing uterine perforation with anIUD/IUS. As previously reported, the post-partum period, lactation and amenorrhoea may increase the risk of perforation.

bias, limitations and generalizability: As the study setting revealed only symptomatic patients or those attending

regular follow-up, the true incidence might be somewhat higher. As there is no specific diagnostic code for uterine perforation or treatment,

it is unlikely that all cases of uterine perforation can be identified in a retrospective study.

study funding/potential competing interests: Helsinki University Central Hospital research funds are

acknowledged.

Key words: IUD / IUS / perforation / incidence / contraception

& The Author 2012. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved.

For Permissions, please email: [email protected]

Human Reproduction, Vol.27, No.9 pp. 26582663, 2012

Advanced Access publication on July 3, 2012 doi:10.1093/humrep/des246


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Introduction

Uterine perforation is an uncommon but feared complication of intra-

uterine contraception. Most previous studies on uterine perforation

have concerned the use of copper intrauterine devices (Cu-IUDs).

However, the levonorgestrel-releasing intrauterine system

(LNG-IUS) is increasingly popular in many countries.

Previously reported perforation rates with Cu-IUDs vary from 0 to

2.2/1000 insertions (Andersson et al., 1998; Caliskan et al., 2003;

Harrison-Woolrych et al ., 2003). In a clinical study in which a

Cu-IUD and the LNG-IUS were compared, recorded perforation

rates were 0/1000 follow-up years with the Cu-IUD and 1/1000

follow-up years with the LNG-IUS (Sivin and Stern, 1994). The few

published studies on uterine perforation in connection with the

LNG-IUS include one retrospective case study showing an incidence

of 2.6/1000 insertions, based on intrauterine device (IUD) sales and

perforations reported by gynaecologists, and one summary of

reports from the New Zealand Intensive Medicines Monitoring Pro-

gramme, monitoring adverse drug events, showing an incidence of

0.9/1000 insertions based on the results of a 3-year survey ( Zouh

et al., 2003; van Haudenhoven et al., 2006). In addition, the largeongoing international prospective EURAS-IUD study (European

Active Surveillance Study for Intrauterine Devices) revealed perfor-

ation rates of 0.68/1000 insertions for the LNG-IUS and 0.41/1000

insertions for Cu-IUDs at 1 year of follow-up (Heinemann et al.,

2011).

Most perforations are thought to occur at insertion either via the

uterine sound or the inserter and thus the IUD/intrauterine system

(IUS) is inserted directly into the abdominal cavity or passes there

through an iatrogenic opening in the uterine wall (Zakin et al.,

1981a,b; Heartwell and Schlesselman, 1983; Andersson et al .,

1998). Many patients are asymptomatic and perforation may be dis-

covered at routine follow-up or in connection with an unintended

pregnancy. Possible symptoms of perforation include abnormal bleed-ing patterns and abdominal pain. When the IUD threads are not visible

during a check-up, perforation cannot be excluded. In most cases, the

device can be found in the uterus (Marchi et al., 2012). As IUDs can be

seen in vaginal ultrasonography, this is often enough to locate the

device, but alternatively X-rays, computerized tomography or magnet-

ic resonance imaging can be used in locating missing devices (Boortz

et al., 2012). The threads might have been cut too short, turned

upwards or the device might have turned in utero, drawing the

threads out of place. If the patient is pregnant, growth of the uterus

retracts the threads. If the IUD/IUS cannot be found in utero, perfor-

ation must always be considered, although expulsion is more common

(Millen et al., 1978; Zakin et al., 1981a,b; Sivin and Stern, 1994; van

Grootheestet al., 2011).

Proposed risk factors of uterine perforation include the immediate

post-partum period and breastfeeding, regardless of the timing of in-

sertion (Heartwell and Schlesselman, 1983; Andersson et al., 1998;

Caliskanet al., 2003;van Haudenhoven et al., 2006). Both Andersson

and van Haudenhoven have discussed the role of uterine involution

and increased uterine contractility as potential contributing factors

to IUD perforation occurring in the post-partum period (Andersson

et al., 1998; van Haudenhoven et al., 2006). Thus, the World

Health Organisation (2009) recommends intrauterine contraception

to be started after 4 weeks post-partum. Other potential risk

factors include extremes of uterine posture, inexperience of the in-

serter and an inadequate insertion technique (Zakin et al., 1981a,b;

Caliskan et al., 2003; Zouh et al. 2003; Harrison-Woolrych et al.,

2003). Increasing parity has been reported both to increase as well

as reduce the risk (Heartwell and Schlesselman, 1983; Caliskan

et al., 2003).

IUDs have traditionally been a popular form of contraception in

Finland, at present accounting for 18% of all contraceptive methods

used and being second after oral contraceptives (Taloustutkimus,

2009). In addition, the LNG-IUS is increasingly used for treating bleed-

ing disorders and as part of hormone therapy for climacteric symp-

toms (Anderssonet al., 1992, Gemzell-Danielsson et al., 2011). The

purpose of the present retrospective population-based study was to

assess the incidence and factors associated with uterine perforation

with current types of IUDs in the area of the hospital district of Hel-

sinki and Uusimaa, which includes 1.5 million inhabitants, 29% of the

Finnish population (December 2011).

Materials and methods

Before initiation of the study, the Ethics Committees of the Hospital ofHelsinki 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 gy-

naecological 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 Decem-

ber 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.

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 (NovaTw) and LNG-IUSs

(Mirenaw) 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

for29% 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

Incidence of IUD/IUS perforation 2659


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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 stat-

istical 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 MannWhitney and chi-square tests as appropriate. Statis-

tical significance was set at P 0.05.

ResultsDemographics

Patient demographics grouped by the type of device are shown in

Table I. The groups did not differ statistically as regards age, BMI,

parity, type of delivery, number of miscarriages, terminations of preg-

nancy or history of pelvic surgery. More women in the Cu-IUD group

had a history of prior curettage, whereas multiple procedures were

more common in the LNG-IUS group (P 0.05).

Incidence

We found an overall incidence of uterine perforation of 0.4/1000 sold

devices (both Cu-IUDs and the LNG-IUS) between 1996 and 2009.

More perforations occurred in connection with the LNG-IUS during

the latter half of the period (20032009), yet the incidence did not

change significantly (Fig. 2). This is explained by increased LNG-IUS

sales. Table II shows annual as well as overall incidences of uterine

perforation in connection with both types of IUD.

Characteristics of women undergoing

surgical treatment for IUD/IUS perforation

Post-partum period and breastfeeding

At insertion, 45 patients (66%) had given birth during the preceding 12

months (Fig. 3). There were 15 patients (22%) had had the device

inserted ,3 months post-partum and 38 (55%) at ,6 months post-

partum. One-third of the women (23) had not delivered within theyear preceding insertion.

Among those with known lactation status, breastfeeding at the time

of insertion was significantly more common in the Cu-IUD group (53%

versus 25%, P 0.05). Most breastfeeding women (n 19, [90%])

had given birth during the last 6 months (P, 0.001) and 17 of

them were amenorrhoeic (P, 0.001).

Insertion-related data

The devices were inserted at different types of health-care units: 17

(25%) at primary health-care clinics, 14 (21%) at family planning

clinics, 15 (22%) by private obstetricians/gynaecologists and 7 (10%)

at hospitals. For 15 (22%) of insertions, no information was available.

General practitioners inserted 27 (40%) and gynaecologists 22 (29%),

but for 21 (31%), no information was available.

Pain at insertion was reported by 32 women (47%), whereas no

pain or minimal pain was reported by 9 (13%). However, five (7%)

of the patients had had the device inserted under general anaesthesia

because of previous problems at insertion or following curettage or

hysteroscopy. These five women had not delivered within the previ-

ous year. For 22 women (32%), no information on pain was available.

The percentage of painful insertions was 70% in connection with

both types of device. Breastfeeding women had reported more pain

at insertion when compared with women not breastfeeding (75%

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.

Figure 1 Flow chart of the study patients.

2660 Kaislasuo et al.


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versus 64%,P 0.009). The clinically assessed uterine posture (ante-

version or retroversion) at the time of detection of perforation was

not related to reported pain at insertion (P 0.32). Of the patients,

36 (53%) had an anteverted uterus, 11 (17%) had a retroverted

uterus and for 5 (7%) the physicians had varying opinions. Information

was lacking on 16 patients (23%). Only 11 (16%) of patient records

contained a comment on extensive flexion: 5 anteverted, 5 retro-

verted and in 1 case the assessment varied.

The median time from insertion to diagnosis was 5 months (0

days69 months), and the median time from diagnosis to surgical

treatment was 21 days (0 days16 months).

Discussion

We found that women experiencing IUD/IUS perforation represent

typical users of intrauterine contraception: women in their early 30s

with a history of vaginal delivery. The incidence of perforation was

0.4/1000 sold devices in connection with both Cu-IUDs and the

LNG-IUS. Annual variations regarding both types of device were

similar, 0 1.2/1000 with Cu-IUDs and 0 0.9 with the LNG-IUS.

Similar or somewhat higher perforation rates have been reported in

prior studies. The incidence of Cu-IUD perforation in prospective as

........................................................................................

Table I Demographics of patients with surgically

removed perforated IUD/IUS.

n5 68 LNG-IUS,

n5 51

Cu-IUD,

n5 17a

Age (years)

Median (range) 33 (20 54) 32 (2447)

BMI (kg/m2)

Median (range) 23.2 (17. 9 39.6) 22.8 (19.7 36.5)

Data not available 6 2

Nulliparous 1 (2%) 0

Parous 50 (98%) 17 (100%)

Median (range) 2 (06) 2 (1 6)

History of vaginal delivery

Yes 44 (88%) 14 (82%)

Median (range) 2 (16) 2 (1 4)

No 6 (12%) 3 (18%)

History of Caesarean section

Yes 13 (25%) 4 (24%)

Median (range) 1 (13) 0 (1 3)

No 38 (75%) 13 (76%)

History of miscarriage

Yes 12 (24%) 6 (35%)

Median (range) 1.5 (13) 1 (1 2)

No 39 (76%) 11 (65%)

History of termination of pregnancy

Yes 11 (22%) 6 (35%)

Median (range) 1 (12) 1 (1 2)

No 40 (78%) 11 (65%)

Previous IUD use

Yes 10 (20%) 3 (18%)

No 10 (20%) 4 (24%)

Data not available 31 10

History of pelvic surgery

Yes 26 (51%) 12 (71%)

No 25 (49%) 5 (29%)

Endometriosis (laparoscopy) 3 (6%) 0

Salpingectomy (ectopic

pregnancy)

0 1 (6%)

Curettage 12 (24%) 8 (47%)

.1 procedure 5/12 (42%) 2/8 (25%)

LEEP treatment 5 (10%) 0

Gastrointestinal surgery 1 (2%) 2 (12%)

Breastfeeding at the time of insertionYes 13 (25%) 9 (53%)

No 18 (35%) 3 (18%)

Data not available 20 (40%) 5 (28%)

Amenorrhoea at the time of insertion

Yes 9 (18%) 8 (47%)

No 11 (22%) 3 (18%)

Data not available 31 (60%) 6 (35%)

The data are presented as n (%) unless stated otherwise.aFincoid 1, FlexiT 1, NovaT380Ag 10, unspecified type of Cu-IUD 5.

........................................................................................

Table II Incidence of uterine perforation, n/1000 sold

IUDs/IUSs.

1996

2009

1996

2002

2003

2009

Comparison of

19962002

versus 2003

2009 P-values

LNG-IUSannual

variation

0.4 0.3 0.5 0.370 0.9 0 0.6 0.2 0.9

Cu-IUD

annual

variation

0.4 0.4 0.4 0.36

0 1.2 00.9 0 1.2

Combined

annual

variation

0.4 0.3 0.5 0.36

0 0.9 0.08 0.5 0.2 0.9

Figure 3 Time between delivery and IUD/IUS insertion (months).



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well as in retrospective studies has been reported to vary from 0.4 to

2.2/1000 insertions. The perforation incidence as regards the

LNG-IUS has, however, been somewhat higher in retrospective

studies, 0.9 2.6/1000 insertions, in comparison with 0.68/1000

insertions reported in the first large prospective study, the

EURAS-IUD study (Heinemannet al., 2011).

To our knowledge, no prior population-based studies have been

reported concerning the incidence of uterine perforation. The

present work is also one of the largest studies in which factors asso-

ciated with uterine perforation have been assessed. Previously pub-

lished studies on Cu-IUD-associated perforation are case reviews

and case series derived from single clinics as well as prospective multi-

centre studies (Zakin et al., 1981a,b; Heartwell and Schlesselman,

1983; Sivin and Stern, 1994, Andersson et al., 1998; Caliskan et al.,

2003; Harrison-Woolrych et al ., 2003), whereas studies on the

LNG-IUS are case reports and reports on adverse drug events

(Zouh et al., 2003; van Haudenhoven et al., 2006; van Grootheest

et al., 2011). The final results from the prospective EURAS-IUD

study are still to come (Heinemann and Assmann, 2012).

As there is no specific diagnostic code for uterine perforation or

treatment, it is unlikely that all cases of uterine perforation can beidentified in a retrospective study. In the present study, we identified

only cases treated by surgical means (laparoscopy/laparotomy or hys-

teroscopy). Thus, possible IUS/IUD perforations occurring at the time

of insertion and treated immediately by removal of the device were

missed by the present research strategy. In addition, many patients

are asymptomatic as regards the perforation (van Grootheest et al.,

2011). This study is likely to include only symptomatic patients and

those attending regular follow-up visits. Furthermore, we were only

able to identify subjects treated between 1996 and 2009, as a different

coding system was used prior to this. The true incidence of all

IUD-related perforations is likely to be somewhat higher than the

present figures suggest.

Another shortcoming of the study is the lack of controls. As thedevices were inserted in multiple health-care settings, identifying ap-

propriate controls would have been very cumbersome. In addition,

IUD/IUS sales figures were used as a surrogate marker of insertions.

Even though this is prone to several uncertainties, it is assumed that

the overall number of IUD/IUS sold over the period of 15 years is

a reasonable proxy of all insertions occurring in the hospital district

over the study period. However, prospective and systematic data col-

lection remains the only truly reliable way of assessing the rates and

risk factors of uterine perforation.

More than half of all the patients had given birth within the previous

six months and at least one-third of them were breastfeeding and

amenorrhoeic at the time of insertion. A combination of these

factors was common, which coincides with findings in previous

studies (Andersson et al., 1998). Only one of the breastfeeding

women had delivered by Caesarean section (3 months prior to inser-

tion), which suggests that a uterine scar is not a major risk factor.

Breastfeeding women reported more pain at insertion than other

patients with uterine perforations. This finding contradicts a previous

hypothesis suggesting more easily occurring silent perforations (Chi

et al. 1989; Andersson et al., 1998). There were more lactating

women in the Cu-IUD group, but as this is a retrospective non-

randomized study, it is impossible to draw conclusions from this. Al-

though both devices are equally recommended post-partum and for

lactating women, various health-care policies and the womens prefer-

ences may have influenced the choice of device.

The clinical settings where insertion took place and the specialties

of the inserting physicians differed markedly. This reflects the health-

care system in Finland. Also, it is not the specialty of the inserting phys-

ician, but training and continuing insertion experience (National Insti-

tute for Health and Clinical Excellence, 2005) and following

instructions (Harrison-Woolrych et al., 2003) that are essential for

successful IUD/IUS insertions. Many general practitioners and

doctors at family planning clinics insert IUDs/IUSs as often as, or

even more frequently than, gynaecologists at private practices or hos-

pitals. In this study, physicians working in the public sector inserted a

large proportion of the devices, reflecting the fact that the majority of

family planning services are provided by the public sector in Finland. A

large number of insertions resulting in perforation were carried out by

obstetrician gynaecologists. It may be speculated that women with a

prior difficult insertion might have sought specialist services directly.

This is highlighted by the fact that 10% of the perforating devices

were inserted at hospitals, the majority of these procedures occurring

under general anaesthesia.

Only a few uteri were assessed as having a steep flexion angle. Thedistribution of uterine posture was similar to that which is considered

normal, and pain at insertion was not correlated with posture. Severe

pain at insertion might indicate a complication, but as the majority of

women experience some pain at insertion, this factor cannot be used

as a way to separate successful insertions from complicated ones

(Suhonenet al., 2004;Heikinheimoet al., 2010). Difficulties in inserting

the uterine sound or the inserter and pain continuing after insertion

might be better indicators of complication.

In conclusion, as reported in prior studies with different settings, the

incidence of uterine perforation was low, 0.4/1000 sold devices. No

clinically significant differences in incidence or patient characteristics

between the Cu-IUD and the LNG-IUS groups were found. More

than half of all perforating devices were inserted within 6 months ofdelivery and many patients were lactating and amenorrhoeic at the

time of insertion. Finally, as intrauterine contraception is one of the

most widely used contraceptive methods worldwide, we propose

that a specific code for uterine perforation associated with an IUD/

IUS be added in future editions of globally used diagnostic

classifications.

Acknowledgements

We thank Ms Leena Kaikkonen and Mr Jouko Kankaala of Bayer Oy,

Finland, for providing the sales data and estimates regarding the sold

devices.

Authors roles

All authors have equally participated in the study design, analysis of the

data, manuscript drafting and critical discussion.

Funding

Helsinki University Central Hospital research funds are gratefully

acknowledged.

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Conflict of interest

O.H. has lectured and designed educational events with Bayer Ag and

MSD, and serves occasionally on scientific advisory boards for these

companies. The other authors have no conflicts of interest to declare.

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