The ‘prostate-muscle index’: a simple pelvic cavity measurement predicting estimated blood loss and console time in robot-assisted radical prostatectomy

Abstract

This study was to show the impact of ‘prostate-muscle index (PMI)’, which we developed as a novel pelvic cavity measurement, in patients undergoing robot-assisted radical prostatectomy (RARP). We defined PMI as the ‘distance between the inner edge of the obturator internus muscle and the lateral edge of the prostate at the magnetic resonance imaging (MRI) slice showing the maximum width of the prostate’. Seven hundred sixty patients underwent RARP at the University of Tokyo Hospital from November 2011 to December 2018. MRI results were unavailable in 111 patients. In total, 649 patients were eligible for this study. Median values of blood loss and console time were 300 mL and 168 min. In multivariate analysis, body mass index (BMI), prostate volume-to-pelvic cavity index (PV-to-PCI), PMI, and surgical experience were significantly associated with blood loss > 300 mL (P = 0.0002, 0.002, < 0.0001, and 0.006 respectively). Additionally, BMI, PMI, and surgical experience were also significantly associated with console time > 160 min in multivariate analysis (P = 0.04, 0.004, and < 0.0001, respectively). In conclusion, PMI may provide useful information to surgeons and patients in preoperative decision-making.

BPPP: A novel pelvis-prostate model predicting immediate urinary continence after Retzius-sparing robotic-assisted laparoscopic radical prostatectomy

“…Therefore, PMI can be used as an index to evaluate the size of the pelvic space around the prostate. 14 For the above factors that may affect the operation space, such as BMI, PV, PCI and PMI, this study was set as pelvis-prostate model BPPP. We used the AUC value of ROC curve to judge the predictive value of these four parameters.…”

“…It was found that PCI was positively correlated with the recovery of urinary continence 3 months after operation. Kimura et al 14 rst introduced the concept of prostate-muscle index (PMI), the anatomical structure around the prostate, which can re ect the size of the pelvic cavity around the prostate, and found that it is related to the bleeding and the operation time during RARP. The above-mentioned pelvis-prostate model (BPPP) may further increase the operation di culty of RS-RARP with narrow operation space, and further affect the goal of "three wins in a row" of radical prostatectomy (tumor control, urinary control and sexual control).…”