Purpose <p>Large ovarian tumors with a predominantly cystic pattern are uncommon in adolescents. This study evaluates the effectiveness of a decompression technique utilizing a balloon trocar to facilitate ovarian-sparing surgery, while preserving oncologic principles, in adolescent patients presenting with such lesions</p> Methods <p>A retrospective review of four consecutive cases managed by a single surgeon over a 7-year period ending December 2024. We describe the surgical technique of this innovative approach, and provide patient-specific clinical data including histopathologic findings and follow-up outcomes.</p> Results <p>The median patient age was 13 years (range, 10–17), and the median maximum tumor diameter was 17 cm (range, 10–28). The balloon trocar technique enabled a tight seal and closed suction drainage of the tumor cyst fluid, facilitating safe decompression and exteriorization of the mass. All surgeries were completed with negligible morbidity. Histological examination revealed three mature cystic teratomas and one serous cystadenoma. At clinical and ultrasonographic follow-up ranging 8 months to 7 years (median, 6,5 years), all patients remained free of recurrence, maintained regular menstrual cycles with normal-sized preserved ovaries, and expressed high satisfaction with their cosmetic outcomes.</p> Conclusion <p>Large predominantly cystic ovarian tumors are generally associated with a favorable prognosis. Preemptive in situ decompression using a balloon trocar represents a simple, effective, and rapid technique to minimize the risk of tumor spillage. This approach facilitates safe ovary-sparing surgery for these large tumors, while also providing excellent cosmetic outcomes. </p>