(Potential) mishaps of high dose rate vaginal cuff brachytherapy.

PURPOSE: Considering how commonly vaginal cuff brachytherapy is used, there is relatively little literature regarding the potential, albeit low, risk for complications. We present here three potentially serious mishaps, involving cylinder misplacement, dehiscence, and excessive normal tissue irradiation due to unique anatomy.

METHODS: Three patients with potentially serious treatment errors were encountered in the authors' usual clinical practice. Each patient's records were reviewed for this report.

RESULTS: For patient #1, CT simulation revealed grossly inadequate cylinder insertion, most obvious on the sagittal view. For patient #2, CT simulation revealed that the cylinder extended beyond the perforated vaginal cuff and was surrounded by bowel. For patient #3, CT images were used only to verify cylinder depth. A standard library plan, based on cylinder diameter and active length was used. In retrospect, the images revealed an unusually thin rectovaginal septum, with the lateral and posterior vaginal wall thickness estimated to be less than 2 mm. Her fractional normal tissue doses were calculated for this report, revealing a rectal Dmax (per fraction) of 10.8 Gy, D2.0 of 7.4 Gy, and a V100 of 2.8 cc. All doses were far in excess of those anticipated for a minimal 0.5 cm vaginal wall depth.

CONCLUSION: Vaginal cuff HDR brachytherapy is a high volume, routine procedure. Even in experienced hands, however, it carries a risk of improper cylinder placement, cuff dehiscence, and excessive normal tissue dose, all of which could seriously impact outcomes. These potential mishaps would be better appreciated and avoided with more extensive use of CT-based quality assurance measures.