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Research

Short term complications of conisation and long term effects on fertility related outcomes in Denmark: register based nationwide cohort study

BMJ 2025; 388 doi: https://doi.org/10.1136/bmj-2023-078140 (Published 15 January 2025) Cite this as: BMJ 2025;388:e078140

Linked Editorial

Individualised care for cervical precancer
  1. Mathias Aagaard, medical doctor1,
  2. Jessica á Rogvi, medical doctor12,
  3. Frederikke Modin, master student in statistics1,
  4. Dagny Nicolaisdóttir, data manager1,
  5. Volkert Siersma, statistician1,
  6. John Brandt Brodersen, professor134
  1. 1Centre of General Practice, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
  2. 2Department of Gynaecology and Obstetrics, North Zealand University Hospital, Hillerød, Denmark
  3. 3Research Unit for General Practice, Region Zealand, Denmark
  4. 4Research Unit for General Practice, Department of Community Medicine, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway
  1. Correspondence to: M Aagaard mathias.aagaard{at}regionh.dk
  • Accepted 30 October 2024

Abstract

Objective To report on complications of conisation and its effects on fertility and stenosis.

Design Register based nationwide cohort study on routinely collected data using several linked databases.

Setting Primary and secondary care in Denmark, 2006-18.

Population The conisation cohort comprised 48 048 conisations on women aged 23-65 who had undergone conisation within 120 days of a cervical biopsy. The biopsy cohort comprised 48 048 biopsies on women who had undergone a cervical biopsy but not conisation who were matched by age and time of procedure. Women were excluded from the conisation cohort before long term outcome analyses if they had undergone hysterectomy, resection of the uterus, or had cervical cancer or any long term outcomes within the 10 years before their conisation.

Main outcome measures Bleeding, infection, and gynaecological operations within 30 days of conisation (stratified by age, year of conisation, and number of previous conisations) and long term risk of fertility treatment, fertility consultation, stenosis, cervical dilatation, infertility diagnoses, and death at any point after conisation. Long term outcomes were followed up until death, emigration, diagnosis of cervical cancer, hysterectomy or resection of uterus, or the end of 2018. Long term outcomes were analysed with incidence rate ratios from Cox regression models.

Results Bleeding, infection, and gynaecological operations were registered for 2.81% (n=1351), 0.48% (n=231), and 3.95% (n=1897) of all conisations within 30 days of the procedure, respectively. Women in the conisation cohort had increased risk of stenosis (incidence rate ratio 14.81, 95% confidence interval 7.55 to 29.05, 0.41% v 0.03% (n=176 v 12)) and cervical dilatation (2.68, 2.41 to 2.97, 4.01% v 1.58% (n=1735 v 668)) compared with women in the biopsy cohort. No significant differences were observed for the other outcomes when adjusting for baseline covariates (such as age and region of residence). Cervical suturing after bleeding was associated with a substantial increase in the risk of stenosis and cervical dilatation.

Conclusion This study found higher rates of complications within 30 days of conisation than previous studies with comparable outcome definitions, and a substantially increased risk of stenosis and cervical dilatation for women who had cervical suturing to treat bleeding after conisation. However, these results were based on few events in a small subgroup, and are therefore associated with major uncertainty. This study supports previous findings that conisation does not generally increase rates of infertility treatment or infertility diagnoses.

Introduction

Many countries have implemented cervical screening programmes. The aim of these programmes is to reduce the incidence of cervical cancer, and the resulting morbidity and mortality rates from the disease, primarily by identifying precancerous lesions, but also, to a lesser extent, through early detection of localised cervical cancer. Several countries have observed a decrease in the incidence of cervical cancer and mortality from the disease after implementing cervical screening programmes. This reduction is assumed to be largely attributable to screening,1234 however high quality evidence about harms from cervical screening is lacking.5 Without screening, high grade precancerous cervical lesions have been estimated to have a progression rate of 12-40%.126 Because of the risk of malignant progression, conisation treatment is recommended in women with high grade precancerous lesions, primarily identified through cervical biopsies after positive cervical screening, depending on their age, stage of dysplasia, and future pregnancy wishes.78910 It is estimated that over 50 conisations are performed for each cervical cancer death prevented, and six to eight conisations are performed for each cervical cancer prevented,26 which is in accordance with most estimates for the progression rate of high grade precancerous cervical lesions of 12-16% without screening.26

Pregnancies that start after conisation have increased risk of perinatal mortality, rapid labour progression, preterm birth, low birth weight, miscarriage, and ectopic pregnancy.11121314 Complications relating to conisation not associated with birth and pregnancy have been less intensely investigated. An increased risk of cervical stenosis after conisation has been found in several studies.151617 Recent systematic reviews and meta-analyses on the benefits and harms of conisation describe risks of bleeding, infections, and organ damage.1819 However, one of these reviews reported that the included studies were of low to very low quality for most outcomes. Cervical screening participation and the resulting effects on mortality rates and incidence of cervical cancer are monitored in annual reports in Denmark,9 while unintentional harms from cervical screening and conisation are unmonitored. Therefore, development of these unintentional harms over time is not well reported in Denmark, and we have not been able to identify studies examining the development of these harms in other countries.

We have identified three women who became infertile after cervical suturing to treat bleeding following conisation. There is no evidence to suggest that conisation impairs fertility overall or for increased use of in vitro fertilisation treatment in births given by women who have undergone conisation compared with women from the general population.1320 However, we have not been able to identify studies on infertility after cervical suturing to treat bleeding caused by conisation. Infertility after this procedure might be an unknown rare, but severe, complication of conisation. Furthermore, we have not found any studies on fertility treatment rates in women in the general population compared with women who have undergone conisation, regardless of whether they subsequently give birth.

Therefore, this study aims to assess the risks of physical, non-obstetric, short term complications from conisation, defined as bleeding, infection, and subsequent operations within 30 days of the procedure. Furthermore, we estimate the long term risks from conisation on infertility, fertility treatment, fertility consultations, cervical stenosis, cervical dilatation and death, and the effect cervical sutures—as a treatment for major bleeding caused by conisation—have on these outcomes.

Methods

This nationwide, register based cohort study used data on all women in Denmark who had undergone conisation in hospital or in the primary care sector, and had a cervical biopsy taken, during 2006-18. The data were analysed for primary and secondary care contacts with registrations of the short and long term outcomes investigated in this study. Appendix 1 presents the codes used to define exposure, outcomes, and confounders. Additional information and programme codes used for analyses can be obtained from the authors.

Registers

The Danish healthcare system is publicly funded and all citizens have a unique identification number, which makes it possible to link data on healthcare activities as well as data on age, and socioeconomic and demographic factors from national registers. We obtained relevant data from the following registries at Statistics Denmark: The Danish National Patient Register,21 The National Health Insurance Service Register,22 The Employment Classification Module,23 The Income Statistics Register,24 The Population Education Register,25 and the registers Statistics Denmark creates from the Danish Civil Registration System26 on death, migration, and demographic factors. Researchers had access to data from these registers for all women in Denmark who had a cervical biopsy in hospital or in the primary care sector within the study period. Data were used as they appeared in registers.

Study population and design

The study population comprised women living in Denmark who had at least one cervical biopsy from the start of the nationwide cervical screening programme in 2006 to the end of 2018.9 Women who had undergone conisation were then identified and included in the conisation cohort. The remaining women were included in the biopsy cohort. Each conisation and biopsy procedure was treated as a separate case or control, which explains why women can be included several times in the data. Conisations and biopsies were excluded if women had no data available in demographic registers, they were outside the age group invited for cervical screening (23-59 years for 2006, 23-65 years for 2007-18),10,11 or had emigrated or died before their conisation date. Conisations were also excluded for women who had been living in Denmark for less than five of the 10 years leading up to the conisation date, or if the conisation was not within 120 days of a cervical biopsy. This design ensured the conisation cohort could be identified as women who plausibly underwent conisation as a consequence of their biopsy, and limited risk of including incorrect registrations. Biopsies from the biopsy cohort were then matched to conisations from the conisation cohort if the biopsy was within 120 days of the date of the conisation, the biopsied woman was within two years of age and did not meet any of the exclusion criteria already described (dependent on their match’s conisation date). If several matches occurred, a single match was selected at random. Conisations and matched biopsies were excluded from analyses of long term outcomes when women had registered hysterectomies, resections of the uterus (transcervical and laparoscopic), cervical cancer, or any long term outcomes in the 10 years before their conisation.

Outcomes

Short term outcomes investigated were infection, bleeding, and subsequent operations—defined as operations on female genitals, the urinary tract, or retroperitoneal tissue, which were minimally invasive, minor, or major surgery. Outcomes were defined as at least one registration of relevant in-hospital diagnosis and procedure codes within 30 days of conisation. Long term outcomes investigated were infertility diagnosis, fertility treatment, fertility consultation, cervical stenosis, cervical dilatation (performed as an independent procedure), and death. These outcomes were defined as time-to-event data; that is, the time to the first occurrence of relevant diagnosis and procedure codes in hospital or in the primary care sector after the conisation date; censoring events were a cervical cancer diagnosis, hysterectomy or resection of the uterus, emigration, death, or end of follow-up at 31 December 2018. For the long term outcomes, subgroup analyses were performed for women who had been treated with cervical sutures after bleeding within 30 days of conisation.

Covariates

We obtained the following baseline covariates for study participants from the registers: age in years (23-35, 36-50, 51-65), marital status (married or single), equivalent disposable annual income (in DKK: <150 000; 150 000-199 999; 200 000-249 999; ≥250 000), educational attainment level (elementary school (10 years), secondary school including vocational education, short or medium term further education, long term further education), country of origin (Denmark, country with similar healthcare system as Denmark (Sweden, Norway, Iceland, Netherlands, Canada, and the UK), western country, non-western country27), region of residence (Capital, Zealand, Northern Jutland, Central Jutland, Southern Denmark), occupational status (working, out of work, student, pensioner), number of children in household (none, one, two or more) and Charlson comorbidity index (0, 1, ≥2)28 defined as registrations of relevant diagnoses in the 10 years leading up to the conisation date in the Danish National Patient Register. Covariates were chosen to limit confounding factors from demographic factors and the impact of baseline morbidity on long term outcomes.

Statistics

We used χ2 tests to compare baseline characteristics of the conisation and biopsy cohorts. Short term outcomes were reported for both cohorts as incidence and percentage of the total number of conisations and stratified by age, time, and number of previous conisations. Long term outcomes were assessed by incidence rate ratios with 95% confidence intervals estimated using multivariable Cox regression models comparing outcome rates between the conisation cohort (and a subgroup of women treated with cervical sutures after bleeding) and the biopsy cohort. Incidence rate ratios were reported unadjusted and adjusted for baseline covariates. A sensitivity analysis was performed using only the first conisation for women who had several conisation procedures included in the data. Analyses were adjusted for the matching of conisations with biopsies, and repeated conisations on the same woman, through a robust sandwich estimator for the covariance matrix. Conisations and biopsies with missing data for a covariate were omitted from analyses using that covariate. We performed analyses using SAS version 9.4. When applicable, a level of P<0.05 was considered significant.

Patient and public involvement

This study was inspired by several clinical meetings with women who became infertile after cerclage treatment for major bleeding relating to conisation. However, there was no direct patient and public involvement in the formation of the study owing to permission to engage with the affected patients being deemed difficult to achieve for this type of study within the allocated timeframe.

Results

A total of 248 556 women had 383 342 cervical biopsies in Denmark within the study period; 69 230 conisations were performed on these women. Of these, 21 182 were excluded, mostly because the conisation was not preceded by a biopsy, leaving a conisation cohort of 48 048 conisations. All conisations in the conisation cohort could be matched with a biopsy (table 1). Women with long term outcomes registered within 10 years before their conisation date were then excluded, leaving a total of 43 285 conisations and 42 151 biopsies for analysis of long term outcomes (fig 1).

Table 1

Baseline characteristics

View this table:
Fig 1
Fig 1

Selection of study population

Short term outcomes

Overall rates of short term outcomes after conisation for the entire study period were 2.81%, 0.48%, 3.95%, and 6.26% for bleeding, infection, subsequent operations, and any complication, respectively. Short term outcomes were rare in the biopsy cohort. Frequency of conisations declined from 19 046 in 2006-10 to 13 350 in 2014-18. Increased rates of bleeding and subsequent operations were observed over the study period. The number of previous conisations was associated with a higher risk of short term outcomes, with 17.03% of conisations performed on women with at least two previous conisations experiencing at least one short term outcome compared with 6.03% of conisations on women without any previous conisations. Rates of subsequent operations increased with age, while other outcomes had low variance across age groups (table 2). Appendix 2 gives a specification of operation types.

Table 2

Short term outcomes after conisation in Denmark, 2006-18

View this table:

Long term outcomes

Women from the conisation cohort had an increased risk of having a cervical stenosis diagnosis and being treated for cervical dilation compared with women in the biopsy cohort (incidence rate ratio 14.81 and 2.68, respectively). These increased risks remained significant when adjusted for baseline covariates. The cumulative incidence of stenosis and dilatation during the study period were 0.41% and 4.01% for the conisation cohort and 0.03% and 1.58% for the biopsy cohort, respectively. Women in the conisation cohort were significantly less likely to receive fertility treatment and attend fertility consultations in crude analyses, however no significant differences were found in adjusted analyses. No significant differences were observed for the remaining outcomes (table 3). Restricting the analyses to women with no previous conisations did not significantly change outcome risks. Cervical suturing after bleeding within 30 days of conisation was associated with a substantially increased risk of cervical stenosis and dilatation.

Table 3

Long term outcomes in conisation cohort compared with biopsy cohort (Denmark, 2006-18)

View this table:

Stenosis and dilatation increased with age and number of conisations for the conisation cohort. Dilatation decreased in both cohorts during 2014-18. All fertility outcomes decreased with age, however fertility consultations increased throughout the study period in both cohorts. Women in the conisation cohort were significantly less likely to attend fertility consultations at age 35-50 (incidence rate ratio 0.82) and significantly more likely to receive fertility treatment in the period 2014-18 (incidence rate ratio 1.34; table 4). The conisation and biopsy cohorts had total follow-up of 262 800 and 267 100 women years, respectively.

Table 4

Stratified incidence rates and incidence rate ratios for long term outcomes following conisation in Denmark: 2006-18

View this table:

Discussion

Principal findings

We found overall rates of short term complications after conisation for the entire study period of 2.81%, 0.48%, 3.95%, and 6.26% for bleeding, infection, subsequent operations, and any complication, respectively. Rates increased with number of previous conisations, with 17% of women with at least two previous conisations having registered at least one short term complication. Conisation rates dropped by nearly a third during the study period, while frequencies of short term complications did not change significantly. Women in the conisation cohort had increased risk of cervical stenosis and cervical dilatation treatment (incidence rate ratio 14.81 and 2.68, respectively), especially those who had cervical sutures to treat bleeding after conisation. However, these findings are associated with major uncertainty because they are based on few events occurring in a small subgroup. We did not observe any significant differences in occurrence of the remaining long term outcomes in adjusted analyses, except in subgroup analyses.

Comparison with other studies

Our study finds substantially higher rates of bleeding and infection than the pooled estimates from a meta-analysis on benefits and harms of conisation that had comparable but more narrow outcome definitions (requiring hospital admission, antibiotics, or blood transfusions). Pooled complication rates ranged from 0.034% to 0.859% for major bleeding, 0.014% to 0.128% for major infection, and 0.022% to 0.276% for organ damage and subsequent operations related to this adverse event, depending on the surgical technique used.18 Another meta-analysis with less well defined outcomes (intraprocedural bleeding, postprocedural bleeding, or infection within seven days) found substantially higher complication rates ranging from 6.54% to 7.39% for bleeding and from 0.25% to 1.91% for infection, depending on the surgical technique used.19 These less well defined outcomes plausibly mean that women with milder complications were included in the outcomes and higher frequencies of complications therefore were observed. Differences in populations between our study and the two abovementioned studies might also explain some of the differences between study findings. We included all women who went to hospital with relevant conditions, and thereby also included women treated with same day emergency care. Therefore, our findings likely represent a larger proportion of women with less severe complications than the study reporting the most conservative estimates, which only included women requiring hospital admission, blood transfusion, or antibiotics and therefore probably represent more severe complications.

We were not able to identify any previous studies investigating subsequent operations after conisation. In addition to organ damage related surgery described above,18 a case report on complications after needle excision of the transformation zone found emergency hysterectomies were performed after 1.9% of conisations.29 Our study found substantially lower rates of hysterectomies, some of which were performed for other indications. Subsequent operations were chosen as a proxy outcome for organ damage and reoperations because we thought that such outcomes would not be well labelled in our available data. Reoperations and reconstructional surgery accounted for 19.7% of operations in the conisation cohort compared with 2.1% in the biopsy cohort.

Conisations induce more mechanical trauma on the cervix compared with a biopsy, which is why an increased risk of stenosis was expected in the conisation cohort. In the Danish healthcare registry system, diagnoses are only registered in hospitals, whereas codes for procedures and treatment are registered in the primary care sector and in hospital. Therefore, cervical dilatation was chosen as a proxy outcome for a cervical stenosis diagnosis in the primary care sector, where most women with stenosis are diagnosed and treated. Untreated women without a diagnosis in hospital are thus not included in our data. Having a diagnosis of stenosis was rare in both cohorts. However, if cervical dilatation is a valid proxy outcome, the risk of stenosis in the conisation cohort is within the range found in earlier studies of 1.3–5.2% of loop electrosurgical excision procedure conisations.15 Not all dilatations can be considered a marker of stenosis, however, as the procedure is also used for other indications, and is not always registered independently. Therefore, our dilatation rates might be underestimated.

Stenosis might inhibit sperm penetration and conception,13 thereby affecting fertility among women who undergo conisation. We found that women who had undergone several previous conisations had increased rates of fertility treatment; however except for the period 2014-18, after adjustment, the differences were no longer statistically significant. This finding supports existing evidence that conisation does not impair fertility in the long term.13 This study further adds that there is no difference in rates of infertility treatment, regardless of whether women subsequently give birth, or in rates of infertility diagnoses, which were only indirectly addressed in previous studies. However, women in the conisation cohort were, at baseline, more likely to have lower income and educational levels than women in the biopsy cohort, factors which have been linked to an earlier age at first birth.30 Furthermore, higher pregnancy rates have been observed among women who have undergone conisation. This finding has previously been proposed to be linked to differences in sexual and behavioural characteristics in women with cervical dysplasia or increased anxiety about their future fertility after treatment.1331 Both of these factors could attribute to women who have had conisation being less likely to seek fertility treatment for age related fertility decline because they have had children earlier in life. This could also plausibly explain the significantly lower rates of fertility consultation and fertility treatment for women in the conisation cohort in the crude analyses and for the age group 35-50.

Previous studies found higher frequencies of cervical suturing after conisation, with a case series on complications after needle excision of the transformation zone finding primary haemorrhage after 12.4% of conisations, with 23% of these being treated with cervical sutures.29 A systematic review on complications after conisation, which did not distinguish between bleeding treated with sutures or vaginal packing, also found higher rates of minor bleeding that needed treatment (ranging from 0.004% to 2.45%, depending on the surgical technique used).18 This suggests that cervical suturing was rare or seldom registered as an independent surgical code in practice in our data, which could plausibly be due to suturing being done perioperatively and not being registered as a separate event, or due to other techniques for achieving haemostasis being more common in Denmark. However, there is also the risk of underreporting of harms in clinical practice; for example, as described in harm reporting after colorectal cancer screening.3233

Strengths and limitations

This study used routinely collected data, which made it possible to examine data collected under real world circumstances for all women in Denmark with long follow-up periods, and so results are generalisable to women who undergo conisation. However, some biases and confounding factors that are difficult to adjust for are present in such studies.34 The biopsy cohort was chosen as our control cohort in an attempt to minimise confounding factors from being screened positive (eg, through Berkson’s bias). However, women who undergo conisation will generally have more severe lesions, and so confounding by indication due to the nature of the dysplasia probably causes some of the observed differences in outcomes between the cohorts. Non-stenosis related long term outcomes did not differ significantly between cohorts, which is why the effect of confounding by indication is probably negligible for these outcomes. We did not have access to the histology of the biopsies, human papillomavirus status, history of sexual behaviour, or smoking history, which have all been associated with the development of cervical intraepithelial neoplasia, cervical cancer, and infertility.353637383940

Additionally, we did not have access to data on transfusions, mesh usage, or prescription of tranexamic acid and antibiotics, explaining why short term outcomes are probably underreported. We also lacked data on conisation techniques, which differ in complication rates, but national clinical guidelines have recommended loop electrosurgical excision procedure and needle excision of the transformation zone throughout the study period.8414243 Gynaecologists in Denmark should follow these guidelines unless they have a valid reason not to. Furthermore, diagnosis codes in the Danish healthcare system are only registered in hospital, explaining why short term outcomes and stenosis and infertility diagnoses are probably underreported, as a substantial number of less severe outcomes are probably either not diagnosed or treated, or if they are, this is done in primary care. Finally, results for women treated with cervical suturing after conisation were based on few events in a small subgroup, and are therefore associated with major uncertainty.

Implications for research and practice

The information women receive before cervical screening is generally biased towards participation and lacks sufficient details about the risk of unintentional harm.44 The rates of complications requiring hospital assessment or treatment after conisation demand better information about the benefits and risks of screening—which conisation is a potential downstream effect of—supporting a well informed choice about participation. Our findings support existing evidence that conisation does not affect fertility, but women who undergo conisation differ substantially in confounding factors related to these outcomes. Prospective research is needed to explore a potential decrease in fertility among women who have been treated with cervical suturing after conisation as we have identified several women with this unknown potential complication, but our data did not represent this group well.

Conclusion

Bleeding, infection, and gynaecological operations within 30 days of conisation requiring hospital assessment are not infrequent. Conisations are associated with a substantial increase in the long term risk of stenosis and cervical dilatation treatment. No effects on rates of fertility treatment, fertility consultations, infertility diagnosis, or all cause mortality were observed after conisation, but significant differences in confounding factors for these outcomes exist between women who undergo conisation and those who do not. Cervical suturing to treat bleeding after conisation was seldom registered according to our definitions, but was associated with an increased risk of stenosis and cervical dilatation (the extent of these risks is associated with much uncertainty). One in 16 women who undergo conisation will experience at least one short term complication requiring hospital assessment, and one in 25 will be diagnosed with cervical stenosis or be treated with cervical dilatation at some point after the procedure.

What is already known on this topic

  • An estimated six to eight conisations are performed for each cervical cancer prevented, and over 50 conisations are estimated to be performed for each cervical cancer death prevented

  • Short term risks of conisation are infection, bleeding, and organ damage, and the procedure increases the risks of perinatal mortality, rapid labour progression, preterm birth, low birth weight, miscarriage, ectopic pregnancy, and cervical stenosis

  • There is no evidence for conisation impairing fertility overall or for increased use of in vitro fertilisation treatment in women who have undergone conisation, and subsequently give birth, compared with those from the general population

What this study adds

  • One in 16 women who undergo conisation will experience one or more short term complications requiring hospital assessment and one in 25 will be diagnosed with cervical stenosis or treated with cervical dilatation at some point after the procedure

  • Conisation does not increase rates of infertility treatment, regardless of whether women subsequently give birth, and it does not increase rates of infertility diagnoses

  • Cervical suturing to treat bleeding after conisation increases the risk of stenosis, but does not affect use of fertility treatment, fertility consultations, or frequency of infertility diagnoses; however, these results are based on few events occurring in a small subgroup

Ethics statements

Ethical approval

Danish law does not require consent from the participants, or approval by ethics committee for use of anonymised register data for research purposes, as in this study.

Data availability statement

Data used in the study are available through public Danish registers. Appendices are available in the web version of this article.

Footnotes

  • Contributors: All authors revised the article critically and approved the final version for publication. MA, JBB, DN, and VS designed the research. DN and MA prepared the data. VS and FM analysed the data. JAR, JBB, VS, DN, and MA drafted the manuscript. JBB, JAR, and MA contributed to clinical interpretation of findings. VS, FM, and DN contributed to critical methodological and statistical input. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted. MA is the guarantor.

  • Funding: The first author of this study, and expenses attributed to the study, have been supported financially by a scholarship in family medicine granted by the Lundbeck Foundation. Furthermore, the study was supported by The Centre of General Practice at Faculty of Health and Medical Sciences (University of Copenhagen). These institutions have not played any role in any aspect of the study.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/disclosure-of-interest/ and declare: this work was supported by the Lundbeck Foundation and the Centre for General Practice at Faculty of Health and Medical Sciences (University of Copenhagen); no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Transparency: All authors affirm that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

  • Dissemination to participants and related patient and public communities: The authors have shared their findings at conferences, and intend to continue doing so. Furthermore, they will use their findings in lectures for pre-graduate and post-graduate students. Finally, JBB is a member of the Danish Health Authorities Advisory Board on National Screening Programmes, where he will disseminate findings in relation to discussions about the cervical cancer screening programme in Denmark.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

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