Figure. To create bilateral peritoneal flaps, the edges of the bladder peritoneum are sutured to the endopelvis, here demonstrated for the endopelvic fascia, as it was performed in the ProLy study. The illustration shows the completed procedure on the right side. ATFP indicates arcus tendineus fasciae pelvis; PIF, peritoneal interposition flap.

Radical prostatectomy is the standard surgical treatment for localized prostate cancer and is actually largely performed robotically in Western countries with appropriate economic structure.¹ Bilateral pelvic lymphadenectomy (PLND) is recommended concomitantly for patients with intermediate- and high-risk prostate cancer.^2,3 Although PLND allows invasive tumor staging, the curative potential of PLND remains unclear and is a major cause of peri- and postoperative complications.⁴ For symptomatic lymphoceles (sLC) as a direct consequence of PLND, rates between 2% and 10% have been reported in the literature.⁵ In this context, symptomatic means lymphoceles causing superinfection, lymphedema, lymphorrhea, hydronephrosis, pain, and compression of the internal iliac vein with consecutive deep vein thrombosis. Lymphoceles in general can be detected by computed tomography in almost every second patient. Men with high BMI and intraoperatively demanding conditions leading to prolonged surgery time are at risk for the postoperative occurrence of lymphoceles.⁶

Different surgical and nonsurgical strategies have been tried to reduce the rates of sLC after robot-assisted radical prostatectomy (RARP) and PLND. In this context, Lebeis et al published a pioneering study of a surgical modification which includes the construction of a peritoneal interposition flap (PIF) after completion of RARP and PLND.⁷ This PIF combines deep bilateral fenestration of the peritoneum with suture fixation of the bladder peritoneum to caudal parts of the perivesical fat (see Figure). The rationale of this surgical modification is to increase the drainage of lymphatic fluid from the pelvic lymphatic bed into the peritoneal cavity and to increase the resorptive peritoneal surface.

In their retrospective, single-center study, Lebeis et al demonstrated that the incidence of sLC was reduced from 11.6% to 0% if a PIF was performed.⁷ Further retrospective studies confirmed these findings, and a meta-analysis of these retrospective studies demonstrated a 77% reduction in the incidence of sLC (P < .001), although there was corresponding heterogeneity between studies.⁸

To translate this indirect evidence into direct evidence, randomized prospective trials have now been conducted to examine the effect of a PIF on overall lymphocele incidence (oLC) and on the incidence of sLC. The results of 4 studies have been published so far.^9-12 While there was little difference between the studies in general, variations between the studies were predominantly related to the placement of fixation, number of sutures, and the type and period of follow-up.

The results of these studies are promising. In the German multicenter ProLy study, the construction of a PIF reduced the incidence of sLC from 8.1% to 3.3% (P = .03).⁹ Furthermore, the incidence of oLC was reduced by 33%, from 33% to 22%, demonstrating a highly statistically significant difference (P = .008). The follow-up period of the enrolled 475 patients included in this study was 90 days postoperatively, the follow-up was performed sonographically, and the PIF was attached to the endopelvic fascia (see Figure).

The Czech PerFix study was performed in a single-center setting and evaluated data from a total of 245 men.¹⁰ The observation period was longest in this study, with a median of 595 days postoperatively. Comparable to the ProLy study, sLC incidence was significantly reduced in the intervention group from 11.5% to 2.4% (P = .011), while oLC incidence was also reduced from 41% to 22% (P = .002). In contrast to the other studies, the follow-up was performed by computed tomography, which might have been a reason for the high oLC incidences. Another difference was the location of peritoneal fixation, which was attached to the periost of the pubic bone.

The US single-center, single-surgeon PLUS study included a total of 216 men.¹¹ While oLC incidences were significantly lower in the PIF group (3.6% vs 14.6%, P = .006), this difference was not observed for sLC (0.9% vs 0.9%, P = .999), but demonstrated exceptionally low incidences in both study groups. The follow-up period was 110 days and the follow-up was performed sonographically.

However, the results of the Pianoforte study contrast with the studies already mentioned.¹² In this multicenter German study, no effect of PIF was observed. The incidence of sLC was not significantly different (8.3% vs 9.7%, P = .82), and although the incidence of oLC was lower in the intervention group, there was no significant difference between groups (17.6% vs 24.2%, P = .26). The follow-up period in this study was 90 days postoperatively and lymphocele occurrence was sonographically controlled. Differing sample sizes and exclusion rates may explain these varying results.

In conclusion, the results of surgical modification of RARP and PLND with PIF are promising at first glance, but meta-analyses are still pending. The results of a meta-analysis of the 4 prospective randomized studies are currently under review and are expected soon. Also expected are the results of the prospective, multicenter PELYCAN study,¹³ which will provide further clarity on the impact of a PIF on postoperative oLC and sLC incidences. If advantages for PIF are also found in both the meta-analysis and the PELYCAN study, future questions will have to examine the optimal PIF modification resulting in the greatest benefit for the patient.