Incidence and Risk Factors for Intrauterine Synechiae in Women With Previous Dilation and Curettage

To estimate the cumulative incidence of intrauterine synechiae in women who have ever had a dilation and curettage (D&C) procedure and to identify covariates associated with diagnosis of the disease.

This is a retrospective cohort study of female Kaiser Permanente Northern California (KPNC) members aged 18-55 years with at least one known prior D&C from January 1, 2010, to December 31, 2020. Data were collected from KPNC electronic medical records, and the diagnosis of intrauterine synechiae was identified using International Classification of Diseases codes. The cumulative incidence of intrauterine synechiae was determined and descriptive characteristics were calculated for demographic and clinical characteristics using χ 2 or Fisher exact and t tests. Extended Cox regression was used to evaluate risk factors in the diagnosis of intrauterine synechiae.

A total of 467 women were diagnosed with intrauterine synechiae, corresponding to a cumulative incidence of 0.8% (467/58,607). Dilation and curettage performed for an obstetric indication was associated with increased hazard of synechiae development (hazard ratio 2.23; 95% CI, 1.77-2.82). Undergoing two D&C procedures increased the hazard 3.96-fold (95% CI, 3.08-5.04); three or more procedures elevated the risk 12.42-fold (95% CI, 7.88-18.70). Other factors significantly associated with an increased hazard of synechiae included a history of pelvic inflammatory disease and uterine artery embolization. In contrast, parity and elevated body mass index (BMI) were negatively associated with synechiae. No significant association was found between sharp curettage and synechiae.

The incidence of intrauterine synechiae after D&C is low, reinforcing the low-risk profile of the procedure, even when sharp curettage is used. However, multiple D&C procedures were strongly associated with an increased risk of synechiae, highlighting the importance of minimizing unnecessary interventions. Additional risk factors include a history of pelvic inflammatory disease and uterine artery embolization. Patients with multiple risk factors should receive comprehensive counseling regarding their elevated risk of developing synechiae.