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Year : 2020  |  Volume : 9  |  Issue : 4  |  Page : 64-67

Nigam's Modified Roeder's Knot in Cutting Seton in High Fistula-in-ano Prevents Rethreading and Reapplication of Seton

Department of General and Minimal Access Surgery, Max Hospital, Gurugram, Haryana, India, India

Date of Submission24-Feb-2020
Date of Decision16-Mar-2020
Date of Acceptance31-Mar-2020
Date of Web Publication31-Dec-2020

Correspondence Address:
Dr. V K Nigam
Dr. V. K. Nigam, A -197, Greenwoods City, Gurugram -122 001, Haryana, India.
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1941-8213.305937

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Background: Fistula-in-ano is known for its recurrence and other complications after surgery, especially in high fistulae cases. Use of a cutting seton is an accepted mode of treatment for high fistula-in-ano cases. Nigam's modified Roeder's knot (NMRK) makes the cutting seton adjustable. The aim of our study is to investigate the results of NMRK application in cutting seton in relation to reapplication, rethreading, postoperative inconvenience to the patient, and postoperative complications. Objectives: To determine whether the NMRK in cutting seton reduces the chances of seton reapplication and postoperative complications in high fistula-in-ano. Design: Squire---Quality Improvement Study. Setting: Patients admitted in various hospitals in Gurugram, Haryana, India. Materials, Methods, and Main Outcome Measures: Eighty high fistula-in-ano patients underwent fistulactomies using the NMRK in both the cutting and adjustable setons between January 2001 and January 2019. Informed consent was obtained from each patient. The patients were evaluated for seton reapplication, inconvenience, recurrence, fecal incontinence, and other postoperative complications. Sample Size: Eighty high fistula-in-ano patients underwent fistulactomies using the NMRK in both the cutting and adjustable setons Results: In our series, no patient suffered fecal incontinence. Three patients (3.75%) had gas incontinence, which gradually stopped within 2 weeks. Most of the setons took 4– 6 weeks to drop. The healing time was 6– 8 weeks for majority of the patients. Two patients (2.50%) developed recurrence after surgery. No patient required readmission or anesthesia for seton reapplication. Conclusion: If the cutting seton with the NMRK is retightened every week, then the drop time of the seton and the total healing time decrease, resulting in reduced incidence of inconvenience, pain, fecal incontinence, and recurrence. Rethreading or reapplication of seton is not required. Limitations: Our study includes only uncomplicated high fistula-in-ano cases. It also excludes complex fistulae, watercan perineum, and fistulae with inflammatory bowel disease or cancer. Conflict of Interest: None.
Keywords: Cutting seton, fecal incontinence, fistula-in-ano, Nigam's modified Roeder's knot, recurrence

How to cite this article:
Nigam V K, Nigam S. Nigam's Modified Roeder's Knot in Cutting Seton in High Fistula-in-ano Prevents Rethreading and Reapplication of Seton. World J Colorectal Surg 2020;9:64-7

How to cite this URL:
Nigam V K, Nigam S. Nigam's Modified Roeder's Knot in Cutting Seton in High Fistula-in-ano Prevents Rethreading and Reapplication of Seton. World J Colorectal Surg [serial online] 2020 [cited 2021 Aug 2];9:64-7. Available from: https://www.wjcs.us.com/text.asp?2020/9/4/64/305937

  Introduction Top

Fistula-in-ano is a chronic abnormal communication between the epithelialized surface of the anal canal and usually the perianal skin.[1] Anal fistulae commonly occur in people with a history of anal abscesses. They can form when anal abscesses do not heal properly.[2] Anal fistulae originate from the anal glands located between internal and external anal sphincters and drain into the anal canal.[3] A 2018 study showed that anal fistulae occur at an incidence of 21 cases per 100,000 people. Fistula-in-ano is more prevalent in males who are in their 30s and 40s.[4] The cause of male preference of this disease is unknown.

Parks, Gordon, and Hardcastle[5] developed a classification system for fistula-in-ano by classifying it into four categories: intersphincteric fistulae (45%), trans-sphincteric fistulae (40%), suprasphincteric fistulae, and extrasphincteric fistulae. In addition, there is a low type of submucus fistula as well. High anal fistulae either pass through the anal sphincter or above it. In contrast, low anal fistulae usually do not pass through the anal sphincter, and if they do, then they pass through the lower part of the anal sphincter. Low anal fistulae are more common than the high anal fistulae and are superficial.

Recurrence and fecal incontinence after fistula surgery are common complications, especially in high anal fistula. Most of the fistulae-in-ano cases are conventionally managed by either fistulotomy or fistulectomy.[6] Majority of the high fistulae require seton application to prevent incontinence due to anal sphincter injury.

A cutting seton is a piece of surgical thread that is tightened at intervals over the anal sphincter so that the sphincter is cut gradually, and not abruptly, to avoid fecal or flatus incontinence. A seton is a nonabsorbable suture. The ischemic compression caused by the tightened seton slowly cuts off the sphincter and simultaneously heals the cut part by creating fibrosis. As a result, the entire sphincter is gradually cut off and fibrosed in a few weeks without causing any incontinence. However, whenever the seton becomes loose, the patient has to be admitted to the operation theater to cut off the loose seton and introduce another one. As a result, the patient ends up receiving anesthesia several times. This problem can be avoided with the Nigam's modified Roeder's knot (NMRK). When the NMRK becomes loose, it can be tightened in OPD while dressing the surgical wound, thereby eliminating the need for admission and administration of anesthesia. In addition, the patient does not feel any pain or discomfort during NMRK retightening as the knot slips smoothly and easily.

  Material and Methods Top

We performed 80 fistulectomies for high fistulae-in-ano between January 2001 and January 2019 using the NMRK in both the cutting and adjustable setons. Ethibond Excel Polyester Suture No. 5 (MB46G), which is a nonabsorbable, braided, and sterile suture, was used. The braided nature of Ethibond helps in preventing the knot from slipping. A written informed consent was obtained from all the patients after providing them with a full explanation of the surgical procedure and its complications. The study had 62 men (77.5%) and 18 women (22.5%) [Table 1]. Most of the patients were between 30 and 40 years of age; the youngest was 17 years old and the oldest was 70 [Table 2]. Majority of the patients in our study were overweight [Table 3]. We considered only high fistulae-in-ano cases. The patients were administered general or spinal anesthesia. Patients with complicated and horse-shoe fistulae and fistulae secondary to malignancy and inflammatory bowel diseases were not included in this study.
Table 1: Distribution of patients according to sex

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Table 2: Distribution of patients according to age

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Table 3: Distribution of patients according to weight

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All patients underwent MRI to visualize the details and branching of the fistula tract. They were given phosphate enema and saline bowel wash on the morning of the surgery. The perianal area was shaved in the operation theater before surgery. Every patient was administered a dose of 500 mg of metronidazole and 1.2 g of Augmentin® intravenously after the sensitivity test in the operation theater before surgery.

The patients were operated in the lithotomy position. Proctoscopy was performed to examine the anal canal and the rectum. A blunt malleable metallic probe was gently inserted into the fistula-in-ano tract. Methylene blue dye was directly injected in the fistula opening with a syringe without needle, and a transparent anoscope was placed in position to see the site of dye exit both in the anal canal and the rectum.

The fistula tract between the sphincter and the skin opening was excised with the help of the malleable probe up to the anal sphincter. The seton was first applied around the sphincter and then the NMRK was applied and its movement on the fixed limb of the knot suture was tested. The knot was subsequently tightened.

Nigam's modified Roeder's knot

The NMRK differs from Roeder's knot. In Roeder's knot, the hitch is applied first then three loops, followed by the application of a half-locking knot. Next, the knot is tightened and slipped on the main limb of the suture. Now, this knot can be tightened and loosened as required. The NMRK has only two loops after the first hitch, while Roeder's knot has three loops. In addition, the NMRK can slip better than Roeder's knot, hence, it is an ideal slip for seton retightening, cuttable and adjustable. The NMRK is used for the anal sphincter as a cutting and adjustable knot in high fistula-in-ano surgeries, while Roeder's knot is used for the cystic duct, cystic artery, and appendix or blood vessel in laparoscopic surgery [Figure 1].
Figure 1: Nigam's modified Roeder's knot

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The patients were called for dressing in OPD till the seton dropped and the wound healed. Every week, the seton was tightened in the OPD while dressing the wound. All patients were informed about the seton and advised not to pull it. The patients were seen every month for 6 months after the fall of the seton. They were then advised to call for any problem such as discharge or incontinence. All patients were discharged from the hospital the next day.

  Results Top

Infection, recurrence, and bowel incontinence are some common postoperative complications after the high-fistula surgery. These complications can occur either immediately after the surgery or even after some time (delayed complications).

In our series, no patient suffered fecal incontinence. Three patients (3.75%) faced gas incontinence, which gradually stopped within 2 weeks. For most of the patients, the seton dropped within 4-6 weeks, which was also the healing time for majority of the patients. Two patients (2.50%) developed recurrence after surgery. No patient required readmission or anesthesia for seton reapplication [Table 4].
Table 4: Postoperative complications

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  Discussion Top

Cutting seton is commonly used in fistula-in-ano surgeries.[7] It is even recommended that complex fistulae should also be treated with a seton.[8] The NMRK makes the seton both adjustable and cuttable. The objective of our study was to evaluate the advantages of NMRK over other knots used in the cutting seton. Surgical treatments for anal fistulae lead to recurrence and incontinence due to three main reasons: Improper identification of the tract and its course; incomplete excision of the tract; and avoiding injury to the anal sphincter. Seton application helps in preventing injury to the anal sphincter.[9] Another study with comparable results showed that one patient (2%) developed fecal incontinence and four (9%) developed a recurrent or persistent fistula at the same location. They concluded that the adjustable cutting seton had a high success rate and low risk of complications.[10]

There is a risk of damage to the sphincter muscle during fistulotomy, which might lead to an unacceptable risk of anal incontinence of varying degrees.[11],[12] Vial et al. reviewed published series from 1966 to 2007 of anal fistula patients treated by a tight or cutting seton technique. Eighteen studies including 19 series and 448 patients were analyzed in detail. The recurrence rate was 5.0% and the overall fecal incontinence rate was 5.6%.[13] In our study, the recurrence rate was 2.5%, the fecal incontinence rate was 0%, and the gas incontinence rate was 3.7%. Setons are available in many varieties. The selection of a seton type and technique depends on the personal preference of doctors. Subhash et al. used silk no. 0 loosely tied with three square knots as the seton, which was tightened at 2-week intervals. They advised the patients to spin the seton by 360΀ so that the knots passed through the fistula tract twice daily. They called this method "progressive migration technique."[14]

Different types of setons are used for this purpose such as silastic tube, silk, linen, braided silk, rubber band, braided polyester, vascular loop, polypropylene nylon, and cable tie.[7] We used MB46G as a seton.

If the cutting seton with the NMRK is retightened every week, then both the drop time of the seton and the total healing time decrease, resulting in reduced incidence of incontinence and recurrence [Table 5] and [Table 6].
Table 5: Distribution of cases according to seton-drop time

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Table 6: Distribution of cases according to healing time

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The fistula track is rethreaded to replace the old seton, which causes pain and discomfort to the patient if performed without anesthesia. According to "The cutting seton," a study at King Faisal Specialist Hospital, KSA, that investigated the morbidity and efficacy of the cutting seton, "Seton were tightened under general anaesthesia at intervals of three to four weeks until cutting was complete".[15]

Roeder's knot, a slip knot, was developed by Albert Hans Roeder, in 1931, for tonsillectomy and was inspired from the hangman's knot.[16] It is mainly used in laparoscopic surgeries. The knot is one of the most important parts of a surgery. If the knot is not properly applied, then it can slip and lead to serious complications such as severe bleeding. Knot application is a specialized job that one must learn to perform such surgeries successfully. In the past, the seton was used to manage anal fistula. However, in the literature, the seton is principally used for only high or complex anal fistulae to avoid fecal incontinence and recurrence.[17]

The NMRK can be used both in the cutting and adjustable setons. It results in an improved outcome with minimal discomfort to the patient during retightening as it does not need rethreading and reapplication of the seton.


Our study includes only uncomplicated high fistula-in-ano. In addition, it excludes complex fistulae and fistulae with inflammatory bowel disease or cancer.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Anorectal Fistula. Merck Manual Consumer Version. 2016-06-27.   Back to cited text no. 1
Colorectal Surgery - Anal Fistula. colorectal.surgery.ucsf.edu. 2016-07-03.   Back to cited text no. 2
Mappes HJ, Farthmann EH. Anal abscess and fistula. Zuckschwerdt. 2001-01-01.   Back to cited text no. 3
Yamana T. Japanese practice guidelines for anal disorders II. Anal fistula. J Anus Rectum Colon 2018;2:103-9.   Back to cited text no. 4
Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg 1976;63:1-12.   Back to cited text no. 5
Seow-Choen F, Nicholls RJ. Anal fistula. Br J Surg 1993;79:197-205.   Back to cited text no. 6
Ritchie RD, Sackier JM, Hodde JP. Incontinence rates after cutting seton treatment for anal fistula. Colorectal Dis 2009;6:564-71.   Back to cited text no. 7
Whiteford MH, Kilkenny J 3rd, Hyman N, Buie WD, Cohen J, Orsay C, et al. Practice parameters for the treatment of perianal abscess and fistula-in-ano (revised).Diseases of the Colon and Rectum 2005;48:1337-42.   Back to cited text no. 8
Lim CH, Shin HK, Kang WH, Park CH, Hong SM, Jeong SK, et al. The use of a staged drainage seton for the treatment of anal fistulae or fistulous abscesses. J Korean Soc Coloproctol 2012;28:309-14.   Back to cited text no. 9
Kamrava A, Collins JC. A decade of selective use of adjustable cutting seton combined with fistulotomy for anal fistula. Am Surg 2011;77:1377-80.   Back to cited text no. 10
Lunniss PJ, Kamm MA. Factors affecting continence after surgery for anal fistula. Br J Surg 1994;81:1382-5.   Back to cited text no. 11
Bokhari S, Lindsey I. Incontinence following sphincter division for treatment of anal fistula. Colorectal Dis 2010;12:35-9.   Back to cited text no. 12
Vial M, Pares D, Pera M, Grande L. Faecal incontinence after seton treatment for anal fistulae with and without surgical division of internal and sphincter: A systematic review. Colorectal Dis 2010;12:172-8.   Back to cited text no. 13
Subhash G, Bhullar JS, Al-Omari A, Unawane A, Mittal VK, Pearlman R. Dig Surg 2012;29:292-300.   Back to cited text no. 14
Isbister WH, Al Sanea N. The cutting seton. Dis Col Rect 2001;44:722-7.   Back to cited text no. 15
Roeder AH, inventors. Albert, Roeder Hans, assignee. Ligator United States patent 2012776. 1935.   Back to cited text no. 16
Pearl RK, Andrews JR, Orsay CP, Weisman RI, Prasal ML, Nelson RL, et al. Role of the seton in the management of anorectal fistulas. Dis Colon Rectum 1993;36:573-7; discussion 577-9.  Back to cited text no. 17


  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]


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