 Patients with newly diagnosed endometrial carcinoma of high risk histologic type or uterine carcinosarcoma whose risk of LN metastasis exceeds 15 will be enrolled on this study. Patients will undergo staging to include hysterectomy and selective lymphadenectomy as per the clinical judgment of the primary Gynecologic Oncologist. Type of hysterectomy and the extent and distribution of lymphadenectomy is at the discretion of the surgeon. All patients will be scheduled for surgical staging. Each subject will have lymph nodes harvested on one side divided into specific basins, and on the contralateral side classified only as pelvic or aortic. Surgical node specimens in the operating room will be labeled by 1 specific nodal basins on the randomly determined side as external iliac, obturator, common iliac, aortic, or high aortic and by 2 pelvic versus aortic common iliac nodes will be considered as part of the pelvic specimen on the contralateral side. 