Pelvic inlet shape measured by three-dimensional pelvimetry is a predictor of the operative time in the anterior resection of rectal cancer

Purpose: We evaluated pelvic shape as a predictor of the surgical outcome of anterior resection in patients with rectal cancer. Methods: In total, 228 patients who had undergone anterior resection (R0 resection and double-stapling anastomosis) for rectal cancer from 2005 to 2014 were included in this study. The anteroposterior (AP) and transverse (T) diameters of the pelvic inlet and outlet and pelvic depth were analyzed on three-dimensional volume-rendered images, and the AP/T ratio was calculated. Univariate and multivariate analyses were performed to determine the predictive significance of the operative time and intraoperative blood loss as surgical outcomes. Results: No difference was observed between the inlet AP/T and patient sex ratios, but the other pelvic dimensions were significantly shorter in males than in females. The univariate analysis revealed that the operative time was significantly correlated with the inlet T diameter and that it tended to be correlated with the outlet T diameter and the inlet AP/T ratio. A multivariate analysis adjusted for operation-related factors revealed that the inlet AP/T ratio was the only independent risk factor for an extended operative time (p = 0.036). None of the pelvic dimensions were independent risk factors for increased blood loss. Conclusion: The shape of the pelvic inlet may be useful for predicting the operative time.