COVID-19 vaccination and postmenopausal bleeding: a retrospective cohort study

Objective: COVID-19 vaccination has been related to menstrual irregularities; however, the effect on postmenopausal women is unknown. The aim of this study was to analyze the prevalence of postmenopausal bleeding (PMB) after COVID-19 vaccination. Methods: A retrospective study was conducted in the Department of Gynecology in Hospital del Mar. Consecutive postmenopausal women with data available and endometrial biopsy were included between February 2021 and January 2022. Patients were stratified between COVID-19 vaccinated and unvaccinated groups. PMB after 30 days from last vaccine dose was considered unrelated to vaccine. Endometrial pathology diagnoses were stratified into benign or malignant. Univariable and multivariable of regression analysis on variables potentially associated with PMB was performed. Results: A total of 381 patients were included, 91 in the vaccinated group and 290 in the unvaccinated group. Prevalence of PMB in the vaccinated group was 75.8% compared to 59.0% in the unvaccinated group (p < 0.005). No increase in endometrial malignant pathology was observed among the vaccinated group (p = 0.189). Multivariable analysis that correlates factors associated with PMB suggests COVID-19 vaccine and malignant endometrial biopsy as independent risk variables. Conclusion: A higher prevalence of PMB was associated with COVID-19 vaccine. Endometrial histological results showed no association with COVID-19 vaccination, but endometrial biopsy should be performed for PMB.