RESUMO
BACKGROUND: In the field of oncofertility, patients with breast cancer are often administered letrozole as an adjuvant drug before and after oocyte retrieval to prevent an increase in circulating estradiol. CASE PRESENTATION: We report a case of abdominal hemorrhage due to an ovarian rupture in a 29-year-old Japanese patient who restarted letrozole 2 days after an oocyte retrieval procedure in which 14 mature oocytes were retrieved. The patient had sought embryo cryopreservation as a fertility preservation option before undergoing treatment for recurrent breast cancer. A day after restarting letrozole treatment, the patient unexpectedly developed severe abdominal pain. Laparoscopic hemostasis was performed to manage the ovarian swelling and hemorrhage. CONCLUSIONS: The ovaries can be restimulated by restart letrozole after an oocyte retrieval procedure. Therefore, reproductive-medicine practitioners should understand the potential complications of letrozole administration in such cases and take steps to ensure that they are minimized.