Localization of trophoblastic disease with vaginal ultrasonography. A report of two cases. Two patients had elevated beta-human chorionic gonadotropin levels and normal abdominal ultrasound examinations. In both instances transvaginal ultrasonography demonstrated a persistent nodule of trophoblastic disease confirmed at the time of hysterectomy. This new imaging modality can assist in the diagnosis of persistent trophoblastic disease in the uterus. 