Surgeons performing permanent colostomies frequently encounter long-term complications that affect patient quality of life. Consequently, parastomal hernia prevention remains a top priority in colorectal surgery. The Chimney Trial recently published its three-year follow-up results, offering strong evidence for using funnel-shaped intra-abdominal mesh to mitigate this risk.

The Chimney Trial: Study Design

This multicenter, randomized clinical trial enrolled 143 patients undergoing surgery for rectal adenocarcinoma. Specifically, these patients underwent either a Hartmann procedure or abdominoperineal excision. Researchers randomized participants to receive either a prophylactic funnel-shaped mesh or no mesh at the time of stoma creation. Notably, the study utilized a single-blinded design to ensure objective evaluations across five European hospitals.

Parastomal Hernia Prevention: 3-Year Outcomes

The long-term results demonstrate a significant clinical benefit for the mesh group. Furthermore, CT scans confirmed parastomal hernias in only 57% of mesh patients compared to 82% in the control group. This represents a 25% absolute reduction in hernia incidence. Similarly, the rate of clinically diagnosed hernias was significantly lower in the mesh group at 10%, while the control group reached 39%.

Safety and Clinical Implications

Safety outcomes remained excellent throughout the three-year observation period. Importantly, the investigators reported no cases of mesh erosion or mesh-related fistulas. Therefore, the funnel-shaped design appears to provide a safe and effective barrier against hernia formation. These findings suggest that prophylactic mesh placement should become a standard consideration for patients requiring a permanent colostomy.

Frequently Asked Questions

What is the benefit of a funnel-shaped mesh design?

The funnel-shaped design allows the bowel to pass through the mesh while providing circumferential reinforcement. This specific shape helps distribute abdominal pressure more evenly and reduces the risk of tissue protrusion at the stoma site.

Did the mesh increase surgical complications?

No. The three-year data showed that the mesh did not increase the incidence of serious complications such as bowel obstruction, erosion, or infection compared to the control group.

How often did hernias occur in the mesh group?

At the three-year mark, only 10% of patients in the mesh group had a clinically detectable hernia. In contrast, nearly 40% of the control group developed a clinical hernia during the same period.

Disclaimer: This content is for informational and educational purposes only. It does not constitute medical advice or establish a doctor-patient relationship. Refer to the latest local and national guidelines for clinical practice.

References

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 Apr 22. doi: 10.1001/jamasurg.2026.1036. PMID: 42018309.

Mäkäräinen E, et al. Parastomal Hernia Prevention Using Funnel-Shaped Intra-Abdominal Mesh Compared to No Mesh: The Chimney Randomized Clinical Trial. JAMA Surg. 2024;159(12):1244-1250.

Wang S, et al. Comparing the effectiveness of prophylactic strategies for parastomal hernia prevention: a network meta-analysis. PubMed. 2025.