Cavernous uterine hemangioma (UH) is an extremely rare benign pathology. The heterogeneity of symptoms and the rarity of such pathology render the diagnosis of UH quite difficult and it often relies on the final histologic examination. A case of a UH, previously diagnosed by ultrasound as a pelvic varicocele involving the uterine fundus, then revealed during a hysteroscopic endometrial resection, is described. The massive bleeding during the procedure caused a life-threatening which required an emergency abdominal hysterectomy. In case of an ultrasonographic diagnosis of atypical pelvic varicocele, more rigorous examinations should be planned before proceeding with an invasive uterine procedure. To the best of the authors’ knowledge, this is the first report describing a UH discovered during an operative hysteroscopy, which could have dramatic consequences for the patient.