Cutting vs. Draining Setons in Complex Anal Fistula Management: A Comprehensive Overview

Anal fistulas are abnormal connections between the epithelialized surface of the anal canal and (often) the perianal skin. They typically develop following an abscess or infection in the anal glands but can also stem from inflammatory conditions such as Crohn’s disease or complications of surgery or trauma. While some anal fistulas can be straightforward and easier to manage, others fall into the “complex” category, presenting surgeons with unique challenges in terms of preserving anal sphincter function and preventing recurrent disease.

Among the multiple strategies for treating complex anal fistulas, seton therapy remains a mainstay. In broad terms, setons are threads or sutures—sometimes made of silicone, silk, or rubber band-like materials—placed through the fistula tract to aid in its drainage or, in some cases, to aid in the gradual cutting of the sphincter muscle and tract. Two primary types of setons are commonly discussed:

• Cutting Setons
• Draining Setons

Both these approaches have their place in fistula management, yet they come with distinct advantages, drawbacks, and considerations regarding patient selection. Below is an in-depth comparison of these two seton therapies, touching on procedural differences, success rates, potential risks, and essential patient factors to consider.

A complex anal fistula is generally characterized by:

• Higher involvement of the anal sphincter (including high transsphincteric, suprasphincteric, or extrasphincteric tracts).
• Presence of multiple interconnected fistulous tracts.
• Association with specific conditions such as Crohn’s disease or radiation therapy.
• Involvement of anterior fistulas in women, where the fistula runs near the vagina.
• Recurrent fistulas or those failing previous surgical interventions.

The primary goals in treating these fistulas include:

• Eradicating the fistula tract(s).
• Preserving anal sphincter integrity to maintain continence.
• Minimizing recurrence rates and complications like infections or abscess formation.

Seton therapy is often leveraged because it can allow for continuous drainage (reducing risk of abscess) or a controlled division of the fistula tract with minimal risk to surrounding muscle structures—depending on whether the seton is a draining or cutting type.

A cutting seton applies gradual pressure to the sphincter muscle fibers within the fistula tract. Over time, with or without repeated tightening, it slowly “cuts” through tissue, allowing for controlled division of the fistula and scarring behind the advancing loop of the seton. This helps the track to heal from the inside out.

• The fistula tract is identified and probed.
• A seton (which can be a silastic loop, braided suture, or similar) is threaded through the tract.
• The seton is then tightened periodically in the outpatient setting, facilitating the progressive slicing effect.

• Potential for complete fistula resolution without needing large excisional surgery.
• Shorter healing times compared to repeated simple drainage for some patients.
• Can be effective in scenarios where a “lay-open” fistulotomy would pose a high risk to sphincter function but controlled cutting is more feasible.

• Pain and discomfort especially after each tightening session.
• Risk of incontinence, which can range from mild soiling to more severe forms of fecal incontinence, depending on the fistula’s proximity to the sphincter complex.
• Incomplete closure of the tract if tension is not appropriately maintained or if the patient’s tissue response is suboptimal.
• Requires careful follow-up and repeated sessions for tightening.

• Patients without significant baseline sphincter dysfunction.
• Individuals who can comply with regular postoperative follow-up.
• Those who might benefit from a more “active” approach to eliminating the fistula more quickly than mere drainage might afford.

A draining seton is placed to keep the fistula tract patent for continuous drainage of any infectious or inflammatory debris. This helps prevent abscess formation and allows the surrounding tissue to heal over time, reducing the likelihood of further infection.

• The surgeon locates the fistula tract and places the seton through it, typically without applying tension.
• The seton remains relatively loose, acting as a “wick” or stent, preventing the edges from sealing prematurely and causing a buildup of fluid.
• Over time, the draining seton may remain indefinitely or until further surgical intervention can be safely performed.

• Low risk of incontinence due to the absence of cutting forces on the sphincter muscles.
• Reduced risk of abscess formation by keeping the tract open and drained.
• Greater comfort for most patients compared to cutting setons, although some discomfort still exists.
• Useful as an interim measure in patients with uncontrolled inflammation (e.g., Crohn’s disease) before final surgical repair.

• Longer treatment times as draining setons alone may not definitively resolve the fistula without subsequent procedures.
• Potential for persistent drainage leading to soiling or discomfort.
• May not fully eliminate the fistula if no definitive surgical intervention follows the draining phase.

• Patients with active infection or inflammation, especially those with Crohn’s disease who may need medical optimization first.
• Those with significant sphincter involvement where immediate surgical repair poses a high incontinence risk.
• Individuals who prefer a more conservative approach or have comorbid conditions that make repeated surgery high-risk.

When choosing between cutting and draining setons, outcomes often hinge on an interplay of factors: the fistula’s anatomical complexity, the patient’s comorbid conditions, sphincter involvement, and follow-up consistency. Some studies indicate:

• Cutting setons can have success rates (defined as fistula closure) of 70–90% in selected cases. However, the incontinence rates can vary from 10–30% depending on the surgical technique, tightening protocol, and anatomic involvement.
• Draining setons alone are typically not curative in the classical sense, so direct comparisons to cutting setons can be skewed. However, draining setons used as a bridge to definitive surgery can reduce infection and inflammatory burden, potentially improving eventual surgical success rates.

Because of the variability in study design, patient populations, and definitions of success, it is critical to tailor therapy to individual patient needs rather than relying solely on broad statistics.

Determining which seton technique is better suited often involves a comprehensive evaluation of:

• Patients with normal or near-normal baseline continence may handle a cutting seton better.
• Those with pre-existing sphincter weakness or risk factors for incontinence (e.g., obstetric trauma) may be more suited to a draining seton approach.

• Inflammatory Bowel Disease (IBD) like Crohn’s disease: Draining setons are often preferred initially, with medical therapy optimization (e.g., biologics) before any attempt at fistula closure.
• Non-IBD Fistulas: Often amenable to direct surgical intervention, with cutting setons used if appropriate.

• Patients with significant comorbidities who are poor surgical candidates may tolerate a draining seton in a more conservative manner.
• Patient lifestyle and compliance levels can strongly influence whether repeated tightening procedures for a cutting seton are feasible.

• High transsphincteric fistulas or those that traverse a significant portion of the sphincter muscle are riskier for a cutting seton approach. A stepwise approach with draining setons may be considered.
• Low-lying fistulas might benefit from the faster resolution often seen with cutting setons.

Under anesthesia, the tract is identified, and the seton is looped through.

• Done every few weeks to months (surgeon’s preference can vary).
• Patients often experience temporary spikes in pain following each tightening; pain management is essential.

• Use of sitz baths, analgesics, and diligent hygiene helps mitigate discomfort and reduce infection risk.
• Patient education on signs of infection (increased redness, fever, foul-smelling discharge) is crucial.

• Regular proctology visits ensure the seton is gradually slicing through the tract while promoting fibrotic closure behind it.
• Once the seton fully traverses the sphincter, it may drop out or be removed in an office setting if the tract has closed.

Similar to the cutting seton, but the seton is left loose.

• Can remain in place for several weeks to months or even longer, depending on infection control, patient tolerance, and the overall treatment plan (e.g., upcoming definitive surgery).

• Frequent cleansing of the area, use of barrier creams to avoid skin irritation from prolonged drainage.
• Monitoring for decreased drainage over time, which might indicate partial closure or additional obstruction.

• Scheduled proctology appointments to track the drainage and look for signs of healing or complications.
• In many cases, once inflammation is controlled or the fistula tract is “mature,” further surgical intervention—such as a fistulotomy or advancement flap—may be planned.

Both cutting and draining setons have a place in the management algorithm for complex anal fistulas:

• Pros: Potentially definitive; faster closure; suitable for select patients.
• Cons: Higher incontinence risk; requires repeated tightening.

• Pros: Lower incontinence risk; helps manage infection and inflammation; fewer immediate interventions needed.
• Cons: Usually not definitive as a standalone therapy; can be associated with persistent drainage and patient discomfort over time.

An in-depth conversation with the patient about these factors is essential. Decisions are rarely cut-and-dried, and a patient’s lifestyle, work situation, tolerance for repeated office visits, and comorbidities all play a major role.

Regardless of seton type, postoperative and ongoing care can significantly impact patient satisfaction and outcome:

• Over-the-counter pain relievers (e.g., NSAIDs) or prescribed medications if needed.
• Sitz baths (warm water soaks) can reduce local discomfort and promote cleanliness.

• A balanced, high-fiber diet can help maintain regular bowel movements without straining, reducing discomfort during defecation.
• Adequate hydration supports healthy bowel function.

• Most patients can resume normal activities within days, but caution with strenuous exercise or heavy lifting until healing is well underway.
• Some prefer using protective pads or dressings to handle any drainage and to maintain hygiene.

• Signs of infection like redness, swelling, severe pain, foul smell, or fever warrant immediate medical attention.
• Persistence or worsening of drainage might signal that the seton has shifted or that an additional branch of the fistula is undrained.

• Essential for adjusting tension in cutting setons.
• Allows the surgeon to monitor the trajectory of healing in draining setons.
• Supports decision-making about additional interventions, such as advancement flaps, fistulotomies, or the potential removal of the seton.

• Pregnant women with complex fistulas might require a more conservative approach until after delivery unless there is an urgent issue.
• Draining setons can help manage symptoms and infection risk during pregnancy with minimal intervention.

Choosing between a cutting or draining seton for a complex anal fistula is rarely a straightforward choice. The decision should reflect:

• Anatomical complexity (extent of sphincter involvement, number of tracts).
• Patient’s baseline continence and risk tolerance.
• Presence or absence of active infection or inflammatory disease (e.g., Crohn’s disease).
• Availability of close follow-up and the patient’s ability to adhere to repeated clinic visits if using a cutting seton.

In some cases, a two-stage approach is employed:

• Initial Draining Seton Placement – Control infection and inflammation while preserving sphincter.
• Definitive Procedure – Once the area stabilizes, surgeons may convert to a cutting seton or proceed with other definitive surgical methods (fistulotomy, endorectal advancement flap, or plugs).

Complex anal fistulas require a nuanced, patient-centered approach. While cutting setons may offer a more definitive solution, they pose a higher risk for incontinence and demand frequent, careful follow-up. Draining setons, on the other hand, provide effective drainage, reduce infection risk, and often serve as a crucial bridge to more definitive treatment—particularly in the context of inflammatory bowel disease or when immediate surgical repair is contraindicated.

Ultimately, there is no “one-size-fits-all” answer, and individualized treatment is paramount. With diligent assessment of sphincter function, fistula anatomy, patient preferences, and comorbid conditions, surgeons can optimize treatment strategies, thereby improving healing rates and preserving quality of life. By understanding the key distinctions between cutting and draining setons, both patients and practitioners can make informed decisions that strike the right balance between efficacy and safety in the management of complex anal fistulas.