Intra-abdominal Mesh is effective in preventing Parastomal Hernia, finds trial: JAMA

An innovative multicenter clinical trial found that the use of a funnel-shaped synthetic mesh significantly reduces the incidence of parastomal hernias in patients undergoing surgery for rectal cancer. The Chimney Trial, conducted between February 2019 and September 2021 in Finland and Sweden, showed the effectiveness of this new approach. The trial results were published in the journal JAMA Surgery. 

Parastomal hernias are tissue or organs that protrude through the abdominal wall near a stoma. These are common but quite challenging complication following surgeries like abdominoperineal resection and the Hartmann procedure. While previous research advocates the use of prophylactic mesh to prevent these hernias, the practice remains controversial due to mixed evidence on its effectiveness and safety. The Chimney Trial was carried out with an aim to investigate whether a permanent, funnel-shaped intraperitoneal mesh could successfully prevent parastomal hernias.

The trial is a randomized, multicenter, single-blinded trial enrolling 143 patients, all of whom had rectal adenocarcinoma and were undergoing either laparoscopic or robotic-assisted surgery or the Hartmann procedure for rectal adenocarcinoma that resulted in a permanent colostomy. The patients were randomly assigned to either the intervention group, where the funnel-shaped Polyvinylidene fluoride (PVDF) mesh was used, or a control group, which received no mesh. At the end of the 12-month follow-up, 121 patients had completed the study, with 68 in the mesh group and 67 in the control group. The primary outcome measured was the incidence of parastomal hernias confirmed by CT scans.

Findings:

• The results were striking. 
• CT scans could be evaluated in 58 patients in the mesh group and 59 patients in the control group at the 12-month follow-up.
• Only 10% of patients in the mesh group developed a hernia, compared to 37% in the control group.
• A 27% reduction in hernia incidence was seen that was statistically significant (95% CI, 12-41; P < .001).
• Additionally, the study evaluated clinical parastomal hernias as a secondary outcome where only 2% of patients in the mesh group developing a clinical hernia, compared to 43% in the control group showing a significant difference of 41% reduction (95% CI, 29-55; P < .001).
  
• Despite the success in preventing hernias, the trial did highlight some concerns regarding complications. The number of patients experiencing Clavien-Dindo class II ileus was significantly higher in the mesh group (35%) compared to the control group (17%) with a 18% difference (95% CI, 3-32; P = .006).
• However, no major differences were noted in other stoma-related complications, surgical site infections, operative times, reoperations, or quality of life between the two groups.

Thus, the researchers concluded that the use of funnel-shaped mesh led to a notable reduction in hernias, suggesting that the funnel-shaped mesh could be a feasible and effective option for preventing parastomal hernias. Despite the presence of higher Clavien-Dindo II ileus in the mesh group, there were lesser complications and improved quality of life. 

Further reading:

Mäkäräinen E, Wiik H, Nikberg M, et al. Parastomal Hernia Prevention Using Funnel-Shaped Intra-Abdominal Mesh Compared to No Mesh: The Chimney Randomized Clinical Trial. JAMA Surg. Published online August 28, 2024. doi:10.1001/jamasurg.2024.3260.