When two diseases collide: Endometriosis as a risk factor for severe pelvic inflammatory disease

Our objective was to compare the severity of pelvic inflammatory disease (PID) in hospitalized women with and without endometriosis, and to assess whether deep endometriosis is associated with worse clinical outcomes.

A single-center retrospective cohort study was conducted from January 2018 to December 2023, including women hospitalized for PID in a tertiary care endometriosis center. Patients were classified based on the presence of endometriosis, as diagnosed by transvaginal ultrasound (TVUS). Clinical, microbiological, and imaging data were analyzed. Primary outcomes included treatment failure, length of hospital stay, need for urgent surgery, and recurrence. A subgroup analysis was performed within the endometriosis group to assess the impact of deep endometriosis.

Of 159, 48 (30.2%) had endometriosis. Compared to those without the disease, women with endometriosis were older and had significantly higher rates of adnexal findings on TVUS (95.8% vs. 73.8%, p = 0.01), mostly suspected infected endometrioma. Vaginal and endocervical cultures were negative in 72.9% of endometriosis patients, and only one tested positive for sexually transmitted disease, in contrast to 42.3% positivity in the non-endometriosis group (p <0.01). Patients with endometriosis showed significantly higher rates of treatment failure (35.4% vs. 17.1%, p = 0.01), recurrence (31.3% vs. 11.7%, p = 0.01), and longer hospital stays (6.1 vs. 3.9). In the deep endometriosis subgroup, treatment failure and recurrence rates were higher, although these differences did not reach statistical significance.

Endometriosis is a significant risk factor for more severe PID, contributing to worse clinical outcomes, including higher treatment failure, prolonged hospitalization, and greater recurrence. Particularly, those with deep endometriosis seem to have a more severe clinical course.