The use of a funnel-shaped intra-abdominal mesh during permanent colostomy formation after rectal cancer surgery significantly reduces parastomal hernia rates over three years without increasing complications, according to long-term randomised trial data.

Parastomal hernia is one of the most common long-term complications following permanent colostomy, yet the role of prophylactic mesh continues to be debated in colorectal surgery.

The single-blinded, randomised Chimney trial, published in the journal JAMA Surgery, evaluated the long-term effectiveness and safety of funnel-shaped polyvinylidene fluoride intra-abdominal mesh placement for preventing parastomal hernia following surgery for rectal adenocarcinoma.

Conducted across four hospitals in Finland and one in Sweden, the study screened 439 patients undergoing laparoscopic or robotic abdominoperineal excision, or Hartmann’s procedure, of whom 143 were randomised to receive either a funnel-shaped mesh (n=68) or no mesh (n=67).

At three years, 50 patients in the intervention group and 51 controls were available for clinical analysis, with computed tomography (CT) scans obtained in 44 and 39 patients, respectively.

The primary endpoint was CT-confirmed parastomal hernia at 12 months, while secondary outcomes included a clinical diagnosis during five-year follow-up, CT-confirmed parastomal hernia at three years, parastomal hernia repair rates, stoma-related complications, re-operations and quality-of-life measures.

Funnel-shaped mesh and parastomal hernia incidence

At three years, CT-confirmed parastomal hernia occurred in 57% of patients with mesh compared with 82% in the control group. Clinically diagnosed parastomal hernia was also significantly lower in the intervention group, affecting 10% of patients compared with 39% of controls.

Parastomal hernias in the control group were significantly larger, with a median volume of 185.9 mL compared with 86.8 mL in the intervention group. Fascial defect size was also larger in controls, with a median diameter of 7.2 cm compared with 4.9 cm in patients receiving mesh.

Importantly, only one patient in the mesh group required surgical parastomal hernia repair during follow-up compared with four patients in the control group.

Quality-of-life scores, measured using the 36-Item Short Form Health Survey and Colostomy Impact Score, were found to be similar between groups.

The authors noted that although radiological detection increased over time in both groups, many that were CT-detected remained asymptomatic and clinically insignificant, suggesting that funnel-shaped mesh may reduce progression to clinically relevant disease requiring intervention.

Long-term findings support mesh use

Rates of stoma-related complications, bowel obstruction and reoperation did not differ significantly between the groups, supporting the safety of intra-abdominal mesh use when standardised techniques are applied.

According to the authors, the findings ‘challenge long-standing scepticism toward mesh-based prevention and underscore the importance of mesh design’. However, several trial limitations were acknowledged, including early termination on ethical grounds after parastomal hernia rates in the control group exceeded the predefined threshold, which reduced the final sample size and statistical power.

Complete blinding after discharge was also not feasible, potentially introducing detection bias, while the relatively low mean body mass index of participants and the fact that the trial was conducted in highly specialised centres may limit generalisability.

Despite these limitations, funnel-shaped polyvinylidene fluoride intra-abdominal mesh appears to be a safe and effective strategy for preventing clinically significant parastomal hernia following rectal cancer surgery, and the authors advocate broader implementation studies to assess reproducibility across different surgical settings.

Reference
Mäkäräinen E et al. Prevention of parastomal hernia with funnel-shaped intra-abdominal mesh vs no mesh for rectal adenocarcinoma surgery: 3-year follow-up of a randomized clinical trial. JAMA Surg 2026; April 22:doi 10.1001/jamasurg.2026.1036.