title: Accuracy of transrectal ultrasonography to evaluate pathologic prostate weight: correlation with various prostate size groups.
abstract: OBJECTIVE
  To report the accuracy of transrectal ultrasonography (TRUS) to measure prostate size before robotic-assisted radical prostatectomy using the prolate ellipsoid formula and its correlation to the weight of the postoperative prostate specimen, for different prostate size groups.
  
  
  METHODS
  Preoperative prostate size estimated by TRUS and the weight of postoperative prostate specimens were collected from 440 men undergoing robotic-assisted radical prostatectomy. Patients were grouped according to preoperative prostate size: <30, 30-60, 60-80, and ≥80 g. To evaluate accuracy, the mean absolute percentage of error was used. The mean percentage of error was used to indicate whether the estimation of TRUS had a tendency to overestimate or underestimate prostate size. The correlation between both measurements was analyzed for each size group.
  
  
  RESULTS
  Accuracy of TRUS estimation was associated with increased prostate size. TRUS estimation was more accurate for larger prostates. The mean absolute percentage of error of each group was 38.64% (<30 g), 21.33% (30-60 g), 13.23% (60-80 g), and 14.96% (≥80 g). Correlation followed a similar size-dependent trend, with a stronger r coefficient for larger prostates: 0.174 (<30 g), 0.327 (30-60 g), 0.457 (60-80 g), and 0.839 (≥80 g). Interestingly, smaller prostates were underestimated, whereas larger glands (≥80 g) had a tendency to be overestimated by TRUS.
  
  
  CONCLUSIONS
  This study demonstrates that the accuracy of the prolate ellipsoid formula for TRUS varies according to prostate size. Although this formula is fairly accurate for assessing larger prostates, it shows some limitations for smaller prostates. This must be taken into account when evaluating treatment modalities such as transurethral incision of the prostate and brachytherapy.
authors: Division of Urology, Department of Surgery, Montreal University Hospital Center, Montreal, Quebec, Canada.
authors: Marc
authors: M
authors: Bienz
authors: Division of Urology, Department of Surgery, Montreal University Hospital Center, Montreal, Quebec, Canada.
authors: Pierre-Alain
authors: PA
authors: Hueber
authors: Division of Urology, Department of Surgery, Montreal University Hospital Center, Montreal, Quebec, Canada.
authors: Naif
authors: N
authors: Al-Hathal
authors: Division of Urology, Department of Surgery, Montreal University Hospital Center, Montreal, Quebec, Canada.
authors: Michael
authors: M
authors: McCormack
authors: Division of Urology, Department of Surgery, Montreal University Hospital Center, Montreal, Quebec, Canada.
authors: Naeem
authors: N
authors: Bhojani
authors: Division of Urologic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Center for Surgery and Public Health, Brigham and Women's Hospital, Harvard Medical School, Boston, MA; Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA.
authors: Quoc-Dien
authors: QD
authors: Trinh
authors: Division of Urology, Department of Surgery, Montreal University Hospital Center, Montreal, Quebec, Canada. Electronic address: zorn.chumurology@gmail.com.
authors: Kevin C
authors: KC
authors: Zorn
mesh_terms: D000368:Aged; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011467:Prostate / Q000000981:diagnostic imaging* / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D012007:Rectum; D015203:Reproducibility of Results; D018084:Ultrasonography, Interventional / Q000379:methods