This retrospective cohort study evaluates the association between postoperative hormonal treatment and recurrence of ovarian endometriosis in women undergoing surgery for ovarian endometrioma. The study includes patients treated at a single center who initiated one postoperative hormonal regimen after surgery. The main objective is to compare the risk of recurrence among women receiving combined oral contraceptives, gonadotropin-releasing hormone agonists, dienogest, or dydrogesterone. Recurrence is assessed during follow-up based on postoperative clinical and ultrasound findings. The results may help clarify the comparative effectiveness of commonly used postoperative hormonal strategies for reducing recurrence after surgery for ovarian endometrioma.

This is a single-center retrospective cohort study designed to evaluate the association between postoperative hormonal therapy and recurrence of ovarian endometrioma after conservative surgery.

Women who underwent surgery for ovarian endometrioma at the study center were screened for eligibility. Patients were included if they initiated one postoperative hormonal regimen within 1 month after surgery and continued the same single-agent treatment for at least 6 months. Patients who did not meet the continuous treatment requirement, received sequential hormonal therapy, or otherwise failed to meet the eligibility criteria were excluded.

Eligible participants were classified into 4 cohorts according to the postoperative hormonal regimen received: combined oral contraceptives (COC), gonadotropin-releasing hormone agonists (GnRH-a), dienogest (DNG), and dydrogesterone. The study was observational in nature, and treatment allocation was based on routine clinical practice rather than assignment by investigators.

The primary objective is to compare recurrence risk among the 4 postoperative hormonal treatment groups. Recurrence is defined as a newly detected ovarian cyst measuring at least 2 cm on ultrasound and documented on at least 2 examinations during follow-up. Follow-up focuses on recurrence within 2 years after surgery.

Clinical, demographic, and disease-related characteristics are collected from medical records and follow-up data. These variables include baseline patient characteristics, reproductive history, disease severity, and relevant surgical findings. The study aims to assess the comparative effectiveness of commonly used postoperative hormonal strategies for long-term management after conservative surgery for ovarian endometrioma.

Because this is a retrospective observational study, no study intervention is assigned as part of the protocol. The findings are expected to provide real-world evidence regarding postoperative medical management and recurrence prevention in women with ovarian endometrioma.

Inclusion Criteria:

• Female patients who underwent conservative surgery for ovarian endometrioma at the study center.
• Initiation of one postoperative hormonal regimen within 1 month after surgery.
• Continuous use of the same single hormonal regimen for at least 6 months after surgery.
• Availability of clinical records and postoperative follow-up data for assessment of study outcomes.

Exclusion Criteria:

• Failure to initiate postoperative hormonal therapy within 1 month after surgery.
• Discontinuation of the postoperative hormonal regimen before 6 months.
• Use of sequential or multiple postoperative hormonal therapies during the initial treatment period.
• Incomplete clinical records or insufficient follow-up data for evaluation of recurrence.

Women with ovarian endometrioma who underwent conservative surgery at a single study center and subsequently received postoperative hormonal therapy in routine clinical practice.