Initial dissection of the lateral fascia reduces the positive margin rate in radical prostatectomy

Positive margins predict an adverse outcome after radical retropubic prostatectomy (RRP). The effect of initial incision of the lateral pelvic fascia prior to urethral transection on positive margins rates is assessed.

The rate of positive margins in 350 consecutive RRPs is compared in two groups without hormonal pretreatment. In group 1 (n = 198), RRP was performed in standard fashion with apical dissection and urethral transection preceding dissection of the lateral pelvic fascia and mobilization of the prostate from the anterior rectal surface. In group 2 (n = 1 52), the initial step consisted of incision of the lateral pelvic fascia along the perirectal surface with prostatic mobilization off the rectum prior to urethral transection. The bladder neck and seminal vesicle dissection was identical in both groups. Specimens were step-sectioned for histologic analysis. Differences in rates of positive margins were analyzed by Fisher's exact test and logistic regression.

The rate of positive margins was reduced from 37.4% in group 1 to 15.8% in group 2. In the logistic regression model, surgical technique, Gleason sum, serum prostate-specific antigen (PSA), and the presence of extracapsular extension were independent predictors of margin status, with group 1 being more than twice as likely to have positive margins than group 2 (P = 0.0076; odds ratio 2.198; 95% confidence interval 1.23 to 3.92). The rate of positive margins was reduced from 45.5% in group 1 to 16.7% in group 2 (P = 0.0046) for non-nerve-sparing RRP and from 33.3% to 15.5% (P = 0.0012) for nerve-sparing RRP. There were no differences in functional outcomes between groups and no rectal injuries in group 2.

Initial dissection of the lateral pelvic fascia during RRP results in a lower rate of positive margins independent of tumor grade, clinical stage, extracapsular extension, and preoperative PSA level.