LAUSR

PURPOSE To assess the value of pelvic cavity index (PCI), as an objective pelvimetry feature, to predict operative time, margin status and early urine continence after extraperitoneal single-port robotic radical prostatectomy (RP). We sought to define an optimal cutoff point for PCI in predicting postoperative outcomes. METHODS Data on 94 patients who underwent extraperitoneal single-port robotic RP and had preoperative cross-sectional imaging were enrolled. PCI was calculated as (Pelvic inlet diameter×Pelvic outlet diameter)/(Pelvic depth). The predictive value of PCI on operative time, surgical margin status and 3-month urinary continence recovery was assessed using regression models. To report the optimum cutoff value, on ROC analysis, we calculated the performance of PCI cutoff points ranging from 5.56 to 10.80 cm by every 0.01 increment. RESULTS No significant associations were noted between clinical characteristics (including PCI) and operative time. Similarly, other than pathological stage, no clinical variables (including PCI) were predictive of positive surgical margin. However, a higher PCI was associated with a significantly higher rates of continence 3-month after surgery (OR 2.44 (1.75 - 5.33); p= 0.01). On ROC- analysis, a PCI cutoff value=8.21 cm yielded the best accuracy (AUC= 0.733, %95 CI 0.615-0.851; p=0.001). No association was noted between variables and 6-month continence rate. CONCLUSION Using a single-port robotic system, operative time, positive surgical margin rate and long-term continence after prostatectomy would be independent of bony pelvis cavity. However, a higher PCI is associated with a higher rate of early continence after the surgery. PCI at a cutoff of 8.21 cm has the optimum performance to predict postoperative urine continence recovery. If validated, this information may be helpful regarding patient counseling before single-port robotic RP.