Artificial radiation menopause: where are the ovaries?

For ovarian ablation using radiotherapy, the pelvis is irradiated using generous fields sizes, as the position of the ovaries is uncertain. To assess the variation in ovarian position, we reviewed 81 sequential CT examinations of the pelvis performed in women under the age of 50 years. Women with pelvic malignancy or previous pelvic surgery were excluded from the analysis, leaving 30 eligible women. One or both ovaries could be clearly identified in 23 of these patients; in 19 (83%), the ovaries were located within the upper two-thirds of a ring defined by the sacroiliac joints, the bony side wall of the pelvis and the symphysis pubis. The ovaries were located outside this ring in four (17%) women. Ovarian position did not appear to be influenced by parity, uterine orientation, the degree of bladder filling or faecal loading within the rectum. The treatment volume for artificial radiation menopause has been variably defined; the upper part of the pelvis may not be included. The results from this retrospective study suggest that the treatment volume should extend from the inferior border of the fifth lumbar vertebra down to a level traversing the middle of the femoral heads and 1 cm lateral to the pelvic side walls.