Author: Dr Punchoor Ramesh Bhat. 
Date of Acceptance: 24 November 2020.


Many surgical interventions are practiced all over world for anal fistula. Still its rate of recurrence is up to 60%. [1] Sushruta, an ancient Indian surgeon, dedicated two chapters in his text book Sushruta Samhita in 500 BC, on anal fistula, its different methods of surgical excisions and 'Ksharasutra' - 'Medicated Seton therapy' [2]. It is practiced in India with a recurrence rate cited to be less than 4% for crypto-glandular fistula [3]. Success rates may be higher if internal opening or infected anal gland is precisely identified and located. This can be best achieved best by 3 levels of assessment. They include

  1. Digital examination for induration (Right index finger tactile sensation-RIFTS)
  2. Sonofistulography (endoanal scan-TRUS)
  3. Using malleable probe identifying internal opening during surgery.

Here we discuss a case of anal fistula successfully treated with Ksharasutra after 26 previous failed surgical interventions.

Case presentation


A 47-year-old male had a 4-year history of anal fistula and recurrent perianal sepsis. He had undergone 26 interventions under anesthesia at five different medical institutions in the USA including incision and drainage, seton placements, partial fistulotomy and stem cell fistula plug. On examination, a loose drainage seton was in situ at 12 o’clock, 2 cm away from anus with active discharge. The perianal skin was erythematous, tender and inflamed. On digital rectal examination, induration and tenderness were felt at 12 o clock position at the level of dentate line. Trans-anal ultrasonography showed a fistula tract along the anterior aspect of anal canal, extending supra sphincterically, with internal opening at 12 o’clock at the level of the anal valves, with the existing seton arising 4 mm caudal to the internal opening. (Figure 1).

The patient underwent limited fistulotomy with a new seton placed through the internal opening after accurate location of the internal opening by endoanal scan under anesthesia. The previous drainage seton was removed. Daily dressing of the fistulotomy wound for 2 weeks led to reduced perianal inflammation and thereafter ‘ksharasutra’ was placed. This was then changed at weekly intervals for 16 weeks. Standard method of preparation of Ksharasutra and standard protocol of therapy was followed [3]. At 4 months the fistula had healed completely. There were no signs of recurrence at 28 months follow up.


In 1880, Hermann and Desfosses demonstrated branching of the anal glands within the internal sphincter, submucosa, and opening into the anal crypts [4]. They suggested that infection in the anal glands resulted in extension of sepsis through the intersphincteric space to the perianal tissues [4]. Others have subsequently expanded this theory to account for observed anatomical variants of fistula and abscess formation [5, 6]. Sushruta, an ancient Indian surgeon in 500 BC also studied the pathogenesis of anal fistula [2]. He also documented the difficulties of treating fistula and described various modalities of treatment including Ksharasutra therapy [2].

In all crypto-glandular fistula, identification of location of infected crypt is essential for treatment. Proper identification of the internal opening is an integral part of fistula surgery if an unacceptable high recurrence rate is to be avoided [7].

The key factors in successful Ksharasutra therapy are:

  1. Accurate anatomical delineation of the primary fistula tract - its course, relation to sphincters and location of internal opening. This was achieved in the current case by an expert radiologist who performed the endoanal scan and sonofistulogram. Here, the internal opening had been missed in previous procedures by 4 mm from its actual position. Secondary tracts do not need treatment - a case of anal fistula extending to foot, where only internal opening was treated by Ksharasutra has been reported. In that case neither fistulotomy nor fistulectomy were done for the entire tract in the gluteum, thigh, leg and foot [8].
  2. Selecting the most dependent drainage site while placing the initial thread (primary threading). At subsequent follow-up, fistulotomy wound dressing by specific agents and Ksharasutra helps in cutting and healing of tract, thereby preventing recurrence.
  3. Approaching the fistula with the intent to cure but balancing this against preservation of function (continence) 9.


Ksharasutra can be effective in treating complex anal fistula of crypto-glandular origin where other measures have failed. Transrectal scan helps in accurate placement of thread through infected crypt. Thereafter adequate dependent drainage, cutting and healing actions of Ksharasutra helps in healing of the fistula and thus prevents recurrence.


  1. Bakhtawar N, Usman M. Factors Increasing the Risk of Recurrence in Fistula-in-ano. Cureus. 2019; 11(3): 4200. doi:10.7759/cureus.4200
  2. Singhal G.D, Sharma K.R. Bhagandara chikitsa adhyaya, 17th chapter. Sushrutha samhitha Ancient Indian Surgery part II. Delhi: Chaukambha Sanskrit samsthana; 1972: 319.
  3. Pankaj S, Manoranjan S. Efficacy of Ksharsutra (medicated Seton) therapy in the management of fistula-in-ano. World Journal of Colorectal Surgery. 2010; 2(2) (Art. 6:01-10)
  4. Hermann G, Desfosses L. Sur la muquese de la region cloacale de rectum. (III) Compts Rend Acad Sci. 1880; 90:1301–1302.
  5. Tucker C C, Hellwing C A. Histopathology of anal glands. Surg Gynecol Obstet. 1933; 58:145–149.
  6. Eisenhammer S. The internal anal sphincter and the anorectal abscess. Surg Gynecol Obstet. 1956; 103(4):501–506.
  7. Sainio P, Husa A. Fistula-in-ano. Clinical features and long-term results of surgery in 199 adults. Acta Chir Scand. 1985; 151(2):169‐176.
  8. Bhat Ramesh P. Anal fistula with foot extension treated by Ksharasutra (medicated seton) therapy, a rare case report. Int J Surg Case Rep. 2013; 4(7):573–576. doi:10.1016/j.ijscr.2013.04.004
  9. Abcarian H. Anorectal infection: abscess-fistula. Clin Colon Rectal Surg. 2011; 24(1):14‐21. doi:10.1055/s-0031-1272819

Internal opening and tract; Drainage Seton placed before Ksharasutra

Figure: 01. Sonofistulogram report and diagrammatic representation of fistula

A. Internal opening and tract. B. Drainage Seton placed before Ksharasutra