Funnel-Shaped Mesh Reduces Risk of Parastomal Hernia After permanent Colostomy: JAMA

A new study published in Journal of the American Medical Association support the use of a funnel-shaped mesh as a safe and effective preventive strategy to lower the risk of parastomal hernia (PSH) following a permanent colostomy.

Parastomal hernia occurs when abdominal contents protrude through the abdominal wall near a stoma, often leading to discomfort, cosmetic concerns, and sometimes the need for further surgery. Despite its prevalence, surgeons have disagreed on whether preventive mesh placement is effective or necessary.

Thus, this investigation enrolled patients undergoing major colorectal procedures, including abdominoperineal excision and Hartmann procedure, most commonly performed for rectal adenocarcinoma. Out of 439 screened individuals, 143 were randomized into two groups, where one received the mesh and one underwent standard surgery without it.

The findings from the Chimney Trial, across the hospitals in Finland and Sweden report that a funnel-shaped surgical mesh, placed at the time of colorectal surgery, significantly reduces the risk of PSH over a 3-year period, without increasing complications.

After 3 years, 101 patients remained available for analysis. CT scans confirmed PSH in 57% of patients who received the mesh, when compared to 82% in the control group, which summed up to a 25% absolute reduction. Clinically diagnosed cases showed an even more pronounced difference from just 10% in the mesh group versus 39% without mesh.

Hernias in the control group were significantly larger, with median volumes more than double those observed in patients with mesh implants. This suggests that even when hernias occurred, the mesh may have limited their progression.

The study found no significant increase in complications such as infections, pain, or mesh-related issues, addressing a key concern that has historically limited widespread adoption of preventive mesh techniques. These results provide strong evidence that a funnel-shaped mesh can be both an effective and safe preventive strategy.

The design of the mesh which is tailored to fit snugly around the stoma, may explain its improved performance when compared to earlier mesh approaches. While longer-term data and broader studies may still be needed, the Chimney Trial’s findings could influence surgical guidelines and standard practices.

Reference:

Mäkäräinen, E., Järvinen, J., Kössi, J., Nikberg, M., Wiik, H., Carpelan-Holmström, M., Pinta, T., Lehto, K., Nikki, M., Ohtonen, P., & Rautio, T. (2026). 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: 3-Year follow-up of a randomized clinical trial. JAMA Surgery. https://doi.org/10.1001/jamasurg.2026.1036