Introduction/Background Ovarian cancer has the worst prognosis among all gynaecological cancers. The pre-operative and intraoperative diagnosis of ovarian tumours is imperative to ensure the right operation is performed and to improve patients’ outcomes.

Methodology This was a retrospective study from January 2017 to December 2021. Cases submitted for intraoperative frozen section diagnosis for the ovary and subsequent histopathological diagnosis were analysed. Frozen section cases were categorized as benign, borderline and malignant.

In cases where a pre-operative US and MRI subjective impression of the examiner was given, the diagnosis on imaging was compared to the final histological diagnosis.

Statistical analysis was performed using Stata MP v17.0 software (USA, 2023) and the diagnostic performance of US, MRI and frozen section compared to the final histological diagnosis was recorded.

Results A total of 156 ovarian masses were examined by frozen section. In the histopathological examination, 123/156 of these tumours were epithelial tumours. Pre-operative US subjective impression was made in 63/156 cases and preoperative MRI subjective impression was made in 129/156 cases.

For benign, borderline and malignant tumours, frozen section demonstrated a sensitivity of 90.8% (95%CI 81.9–96.2), 86.8% (95%CI 71.9–95.6) and 97.6% (95%CI 87.4–99.9) respectively, US demonstrated a sensitivity 95.2% (95%CI 76.2–99.9), 20% (95% 4.33–48.1), 57.1% (95%CI 28.9–82.3) respectively and MRI demonstrated a sensitivity of 100% (95%CI 80.5–100), 31.5% (95%CI 19.5–45.6) and 63.2% (95%CI 46–78.2) respectively.

Conclusion Frozen section remains an accurate intraoperative tool for diagnosing the malignant potential of ovarian masses. However, across both imaging modalities and FS, the diagnosis of borderline ovarian tumours remains challenging.

Disclosures nothing to declare