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

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.