Semiflex-assisted vacuum therapy for perianal fistulas: the Semiflex pilot study

Perianal fistulas often require multiple surgical interventions because of their chronic nature. Various sphincter-sparing techniques achieve clinical closure rates of up to 70%, yet recurrence remains a major challenge. Vacuum-assisted closure (VAC) therapy has shown promise in wound healing, but its application in perianal fistulas remains largely unexplored. The Semiflex catheter was developed to facilitate outpatient vacuum therapy without the need for general anesthesia during catheter exchanges. This pilot study aimed to evaluate the feasibility and clinical applicability of the Semiflex catheter in perianal fistula management.

The Semiflex pilot study was a two-part feasibility trial. The first part assessed proof of principle in ten patients, while the second part, a multicentre study, aimed to confirm feasibility in 20 patients. Feasibility included smoothness of insertion and changing of the Semiflex catheters, capability of proper fixation of the Semiflex catheter, maintaining vacuum for more than 48 h, and compliance to the therapy in terms of pain and discomfort. The protocol was scored feasible if at least 50% of the exchanges met all these criteria in at least 70% of patients. Secondary outcomes included clinical fistula closure, radiological healing, and treatment-related adverse events.

Twenty patients were included (median age 39.5 years; 70% Crohn's disease). Thirteen Semiflex treatments were scored as feasible, below the predefined threshold. Clinical fistula closure was observed in 50% of patients, but none showed radiological healing at 3 months. One serious adverse event occurred, requiring early treatment discontinuation, while minor complications, including local skin reactions and pressure sores, were managed conservatively.

Semiflex therapy was feasible in a subset of patients and allowed outpatient treatment. However, maintaining vacuum and achieving long-term fistula closure remains challenging. While Semiflex may have a role in perianal fistula management, further research is needed to refine patient selection and optimize its application.