Introduction

Figure. Kaplan-Meier curve demonstrating the estimated probability of parastomal hernia (PSH)–free survival following cystectomy and ileal conduit in mesh and control arms. SE indicates standard error.

Parastomal hernia (PSH), defined as protrusion of peritoneal content through the abdominal wall defect adjacent to the stoma, is a common complication following cystectomy and ileal conduit (IC) urinary diversion.¹ The incidence of PSH has been reported between 14% to 48%, depending on the diagnostic method (clinical vs radiological), wide-ranging criteria, and duration of follow-up.^2,3 Various strategies have been proposed for PSH prevention, including prophylactic mesh placement at the time of IC construction. Despite level I evidence in the colorectal literature on this subject,⁵ very limited data are available in the urology field.⁶ The aim of this study is to assess the effect of prophylactic biologic mesh on the PSH development in patients undergoing cystectomy and IC.

Methods

This phase 3 randomized controlled trial (RCT; NCT02439060) included patients undergoing cystectomy and IC at University of Southern California between 2016 and 2021. Patients with previous scar or mesh at the level of IC, predicted survival of less than 12 months after surgery, history of allergic reactions attributed to biologic composition, preexisting condition precluding mesh integration (eg, uncontrolled diabetes or chronic steroid use), and those having a colostomy/ileostomy were excluded. Eligible cases were randomized 1:1 to receive prophylactic biologic mesh (FlexHD, median thickness 2.5 mm) using sublay intraperitoneal technique vs standard of care. Follow-ups comprised physical exam and computed tomography imaging every 4-6 months up to 2 years. The primary endpoints were radiological (per Moreno-Matias classification⁷) or clinical PSH, and secondary outcomes were mesh-related complications and development of symptomatic PSH requiring surgical intervention.

Results

A total of 146 patients were enrolled and randomized to mesh (n=72) and control (n=74). The 2 arms were similar in terms of demographics and baseline clinical features. All surgeries and mesh placements were accomplished without intraoperative complications. Median operative time was 30 minutes longer in patients receiving mesh (360 vs 330, P = .16). Ninety-day postoperative wound/stoma and infectious complications were similar between the mesh and control arms (7% vs 8%, and 26% vs 22%, respectively).

Within a median time of 21 months, 8 patients were lost to follow-up, corresponding to a study adherence rate of 94%. The overall incidence of radiological and clinical PSH was 25% (25% in mesh vs 26% in controls) and 11% (11% in both arms), with a median time to radiological and clinical PSH of 8.3 and 15.5 months, respectively. No definite mesh-related adverse events were reported. Five cases (3 in mesh and 2 in control arms) were required surgical PSH repair. On multivariable Cox regression analysis, prior radiation (HR 3.5, P = .03) and pathological T stage >2 (HR 1.9, P = .07) had significant and borderline associations with an increased risk of PSH, respectively. PSH-free survivals in the mesh and control groups were 77% vs 77% at 1 year, 72% vs 63% at 2 years, and 64% vs 39% at 3 years, respectively (see Figure).

Discussion

This is the first RCT report in the United States on prophylactic use of mesh in IC patients. We showed that biologic mesh does not have a protective effect on PSH development in the first year following cystectomy and IC; however, it may decrease the risk of PSH at 2- and 3-year follow-up. Our results are similar to the only other RCT on this topic from Sweden that showed similar incidence of clinical and radiological PSH at 2 years following surgery, yet decreased risk of clinical PSH in the mesh arm at 3 years (HR 0.45, P = .02).⁶

Our study also confirmed the feasibility and safety of prophylactic biologic mesh placement, with only half an hour of additional operative time and no intra- and/or postoperative mesh-related complications. The operative time dedicated to mesh placement was lower than in the Swedish RCT,⁶ which makes our technique more generalizable. Of note, we used a biologic mesh made from acellular cadaveric dermal matrix, compared to nonabsorbable polypropylene mesh used in the Swedish trial.

Taken together, these findings may indicate that prophylactic mesh may be useful in a subgroup of patients with a longer survival and/or those with other risk factors for PSH (eg, prior abdominal radiation). Nevertheless, longer follow-up and quality-of-life economic analyses, as well as the results of the other ongoing trial on this topic,⁸ will help us to better understand the role of prophylactic mesh in IC patients.

Conclusions

The initial results of this RCT suggest that implementation of biologic mesh at the time of IC construction is safe without significant protective effect in first year; yet may decrease PSH development afterward.