Can a Loose Seton Change the Location of a Fistula?
No, a loose seton does not change the location of a fistula tract—it maintains drainage through the existing tract and prevents the development of more complex fistulas by keeping the tract patent. The primary function of a loose seton is to establish and maintain drainage along the established fistula pathway, not to alter its anatomical course 1.
Understanding Seton Function
The loose seton works by:
- Maintaining patency of the existing fistula tract through the sphincter complex to prevent premature closure and abscess formation 1
- Allowing inflammation around the tract to subside while preventing recurrence of abscesses 1
- Preventing the development of more complex fistula tracts by ensuring continuous drainage through the identified pathway 1
The seton is threaded through the cutaneous opening, through the existing fistula tract, across the mucosal opening into the rectum, and out the anal canal—following the established anatomical pathway 1.
What Actually Happens with Seton Placement
Progressive Migration vs. Location Change
Some studies describe "progressive migration" of the fistula tract with certain seton techniques, but this refers to the gradual movement of the seton toward the surface as the tract heals from within—not a change in the fistula's anatomical location 2. This migration represents healing and fibrosis formation around the tract, with the seton gradually working its way to the surface over 2-40 months 2.
Recurrence vs. Location Change
When fistulas "recur" after seton placement (occurring in 19.5% of cases), this represents either:
- Persistence of the original tract due to inadequate drainage 3
- Development of a new fistula from ongoing sepsis or inflammation 3
- Not a migration or change in location of the original fistula 3
Clinical Implications for Your Patient
For a patient with a low trans-sphincteric fistula (≤30% sphincter division) and persistent/recurrent fistula after fistulotomy:
The loose seton will:
- Maintain drainage through the existing fistula tract without altering its anatomical course 1
- Promote fibrosis around the tract to facilitate eventual healing 4
- Prevent abscess formation by keeping the pathway patent 1
Duration and outcomes:
- Keep the seton in place for 3-7 months on average, though duration varies from 3 weeks to 40 months depending on clinical response 3, 5
- Success rates of 75-80% for definitive healing with loose seton technique alone 3, 6
- Recurrence rates of approximately 19.5% may occur, successfully treated by repeating the same technique 3
Critical Pitfall to Avoid
Never use a cutting seton, which involves sequential tightening every 3-4 weeks—this technique has a 57% incontinence rate from forced sphincter transection and is strongly contraindicated 1, 5. The loose seton should remain loose and non-cutting throughout treatment 1.
Management Strategy
For your specific patient with persistent/recurrent low trans-sphincteric fistula:
- Place a loose, fine silastic seton through the existing fistula tract 1, 5
- Ensure adequate drainage of any associated abscess before seton placement 1
- Monitor for 3-7 months with the seton in place, allowing inflammation to subside 3
- Consider combination with medical therapy (antibiotics, anti-TNF if Crohn's disease) for improved outcomes 5, 7
- Remove the seton once the tract has adequately healed from within, typically at 3-7 months 3
The seton maintains the fistula in its current location while promoting healing—it does not cause the fistula to migrate to a different anatomical position 1, 3.