Overview
Definition:
Seton placement is a surgical technique used in the management of complex anal fistulas, particularly those involving a significant portion of the external anal sphincter
A seton is a drain or suture that is passed through the internal opening of the fistula, tract, and external opening, and then secured externally
Its primary role is to provide gradual drainage, allow healing of the fistula tract, and prevent the formation of abscesses while preserving sphincter function.
Epidemiology:
Anal fistulas affect approximately 1-3% of the general population, with a higher incidence in males
Complex fistulas, those requiring seton placement, account for a significant proportion and are often associated with Crohn's disease, prior perianal sepsis, or high trans-sphincteric/suprasphincteric tracts
The incidence of complex fistulas necessitates understanding of seton techniques for successful management.
Clinical Significance:
Complex anal fistulas can lead to significant morbidity, including pain, recurrent abscesses, sepsis, and fecal incontinence if managed improperly
Seton placement is crucial for preventing incontinence by allowing slow healing and sphincter preservation, making it a vital skill for surgeons preparing for DNB and NEET SS examinations who will encounter such cases in their practice
Effective management improves patient quality of life and reduces re-operation rates.
Indications
Indications For Seton Placement:
Primary indication is for complex anal fistulas
This includes high trans-sphincteric fistulas (where more than 30% of the sphincter is involved) and suprasphincteric fistulas
Other indications include recurrent anal abscesses, fistulas in patients with inflammatory bowel disease (e.g., Crohn's disease), actively draining fistulas that are not amenable to immediate fistulotomy, and as a preparatory step for staged procedures to avoid incontinence
In some cases, it may be used for fistula tract maturation prior to definitive surgery.
Contraindications:
Absolute contraindications are rare but include uncontrolled sepsis or abscess that requires immediate drainage, and a patient's inability to tolerate a prolonged treatment course
Relative contraindications include very low-risk fistulas where simpler methods might suffice, and significant comorbidities that could compromise healing
Poor patient compliance is also a significant concern.
Goals Of Seton Therapy:
The main goals are to promote gradual healing of the fistula tract, allow for complete drainage, prevent recurrent abscess formation, and preserve anal sphincter function
Setons act as a foreign body to encourage fibrosis and tract closure or as a drain to keep the tract open and draining pus
The choice of seton and technique depends on the fistula anatomy and the surgeon's preference.
Types Of Setons
Draining Setons:
These setons are typically made of latex rubber tubing or silicone bands
They are passed through the fistula tract and secured externally, usually by tying the ends together
The purpose is to maintain drainage of pus and exudate, thereby preventing abscess formation and encouraging granulation and healing of the tract from the inside out
These are often used for longer-term management.
Cutting Setons:
These are usually made of strong silk or braided polyester suture material
They are gradually tightened over time, typically by a few millimeters every few days or weeks
The gradual tightening cuts through the surrounding tissue, including the sphincter muscle, leading to a slow division of the fistula tract and sphincter
This method aims for eventual healing with minimal loss of sphincter function.
Loose Setons:
These setons are left loosely in the fistula tract and are not tightened
They are primarily used to keep the tract patent for drainage and to prevent closure of the internal opening before the external opening has healed, thus avoiding abscesses
They are often used in the initial management of complex fistulas or in patients with IBD.
Surgical Technique
Preoperative Assessment:
A thorough history and physical examination are essential
Imaging modalities like MRI fistula protocol or endoanal ultrasound are crucial for defining the fistula tract anatomy, including its relation to the sphincters and identifying any associated abscesses
Preoperative antibiotics may be administered
Bowel preparation might be considered for some procedures.
Seton Insertion Procedure:
The procedure is typically performed under anesthesia
After identifying the internal and external openings, a probe or guidewire is passed through the fistula tract
The chosen seton material is then threaded through the tract
For draining setons, the ends are tied loosely
For cutting setons, the suture is tied snugly, and gradual tightening is planned
For loose setons, the material is placed and secured without tension.
Postoperative Care Initial:
Pain management is paramount, typically with analgesics
Patients are usually advised to keep the perineal area clean and dry
Warm sitz baths may be recommended starting 24-48 hours post-procedure to promote comfort and cleanliness
Patients should be educated on signs of infection or worsening pain, which may indicate an abscess.
Management And Follow Up
Monitoring And Adjustment:
Regular follow-up appointments are scheduled, typically every 1-4 weeks depending on the type of seton and patient progress
Draining setons are monitored for patency and drainage
Cutting setons are gradually tightened as planned, with the patient often instructed on how to do this at home with nurse supervision
Loose setons are checked for patency and drainage.
Advancing The Seton:
For cutting setons, the gradual tightening is key
The interval and amount of tightening are determined by the surgeon based on the patient's pain tolerance and the visible effect on the surrounding tissue
The goal is slow, controlled division to allow for sphincter muscle regeneration and minimize incontinence.
Definitive Treatment And Healing:
Healing occurs when the fistula tract closes completely, and the external opening resolves
This can take weeks to months
Once the tract has closed and there is no longer any discharge, the seton can be removed
In some cases, especially with long-standing or complex fistulas, a definitive surgical procedure like fistulotomy or advancement flap may be performed after the seton has facilitated tract maturation or drainage.
Complications
Early Complications:
Pain is common
Bleeding may occur during or after insertion
Abscess formation is a significant concern if drainage is inadequate or if the seton becomes occluded
Infection of the tract or surrounding tissues can also occur.
Late Complications:
The most feared complication is iatrogenic fecal incontinence, particularly with cutting setons if not managed appropriately
Recurrent fistula or failure of healing can also occur
Skin irritation or breakdown around the external opening is a possibility
Stenosis of the anal canal may develop if healing leads to excessive fibrosis.
Prevention And Management:
Adequate pain control and hygiene are essential
Close monitoring for signs of infection or abscess is crucial, requiring prompt drainage if necessary
Careful technique during seton placement and gradual, controlled tightening of cutting setons are key to minimizing incontinence
Patient education regarding hygiene and warning signs is vital for successful management and complication avoidance.
Key Points
Exam Focus:
Understand the different types of setons (draining, cutting, loose) and their specific indications and mechanisms of action
Be prepared to describe the technique of insertion and postoperative management, including the concept of gradual tightening for cutting setons
Know the indications and contraindications for seton placement in complex anal fistulas.
Clinical Pearls:
MRI fistula protocol is invaluable for preoperative planning
Patient selection and education are paramount for compliance
For cutting setons, emphasize the importance of gradual tightening to preserve continence
Consider seton placement as a tool to facilitate healing and prevent incontinence, rather than a definitive cure in itself for all cases.
Common Mistakes:
Failure to adequately assess fistula anatomy preoperatively
Inadequate drainage leading to abscess formation
Aggressive or too rapid tightening of cutting setons resulting in incontinence
Neglecting patient education leading to poor compliance or missed warning signs
Mismanaging fistulas in patients with Crohn's disease, where conservative measures are often preferred.