Transanal opening of the intersphincteric space (TROPIS): a novel procedure on the horizon to effectively manage high complex anal fistulas

Abstract

Anal fistulas, especially complex and high fistulas, are difficult to manage. The transanal opening of the intersphincteric space (TROPIS) procedure was first described in 2017, and a high success rate of over 90% was reported in high complex fistulas. Since then, more studies and even a meta-analysis have corroborated the high efficacy of this procedure in high fistulas. Conventionally, the main focus was to close the internal (primary) opening for the fistula to heal. However, most complex fistulas have a component of the fistula tract in the intersphincteric plane. This component is like an abscess (sepsis) in a closed space (2 muscle layers). It is a well-known fact that in the presence of sepsis, healing by secondary intention leads to better results than attempting to heal by primary intention. Therefore, TROPIS is the first procedure in which, instead of closing the internal opening, the opening is widened by laying open the fistula tract in the intersphincteric plane so that healing can occur by secondary intention. Although the drainage of high intersphincteric abscesses through the transanal route was described 5 decades ago, the routine utilization of TROPIS for the definitive management of high complex fistulas was first described in 2017. The external anal sphincter (EAS) is completely spared in TROPIS, as the fistula tract on either side of the EAS is managed separately-inner (medial) to the EAS by laying open the intersphincteric space and outer (lateral) to the EAS by curettage or excision.

Keywords: Anal fistula; Fistula in ano; Ligation of the intersphincteric tract; Rectal fistula; Transanal opening of the intersphincteric space (TROPIS).

Fig. 1.

The steps of the transanal opening of the intersphincteric space (TROPIS) procedure. EAS, external anal sphincter; IO, internal opening.

Fig. 2.

A 23-year-old male patient with left suprasphincteric abscess with no external opening. He was managed definitively in the first surgery by the transanal opening of the intersphincteric space (TROPIS) procedure. The patient had clinically healed at 3 months postoperatively, and the magnetic resonance imaging (MRI) showed that the fistula had completely healed. (A) Schematic diagram of the axial section. (B) Schematic diagram of the coronal section. (C) Preoperative MRI of the axial T2 section, showing a high internal opening at the posterior midline (arrow, fistula tract). (D) Preoperative MRI of the coronal T2 section, showing a left suprasphincteric abscess with no external opening (arrow, fistula tract). (E) Postoperative 3 months MRI of the axial T2 section, showing a completely healed fistula and the internal opening. (F) Postoperative 3 months MRI of the coronal T2 section, showing a completely healed fistula and the internal opening.

Fig. 3.

Photographs of the patient in Fig. 2, a 23-year-old male patient with a left suprasphincteric abscess with no external opening. (A) Preoperative photograph with no external opening. The blue mark on the left buttock shows the area of maximum induration. (B, C) Immediate postoperative photographs. (B) The final transanal opening of the intersphincteric space (TROPIS) wound inside the anal canal. (C) Final picture after surgery. A drainage tube in the left suprasphincteric abscess can be seen sutured to the skin. This was taken at 3 months postoperatively, after the TROPIS wound (internal opening) had healed completely.

Fig. 4.

A 30-year-old male patient with recurrent right high transsphincteric fistula with multiple branches. He was managed successfully by the transanal opening of the intersphincteric space (TROPIS) procedure, and postoperative magnetic resonance imaging (MRI) at 5 months showed that the fistula had completely healed. (A) Schematic diagram of the axial section. (B) Schematic diagram of the coronal section showing a high transsphincteric fistula with an additional (second) branch extending superiorly along the inferior surface of the right levator muscle. (C) Preoperative MRI of the axial T2 section, showing a high internal opening at the posterior midline (arrow, fistula tract). (D) Preoperative MRI of the coronal short inversion time inversion recovery sequence section showing a right high transsphincteric fistula (yellow arrow) with an additional (second) branch extending superiorly along the inferior surface of the right levator muscle. The complete fistula tract from the external opening to the internal opening can be visualized (white arrows). (E) Postoperative 5 months MRI of the axial T2 section, showing a completely healed fistula and the internal opening. (F) Postoperative 5 months MRI of the coronal T2 section, showing a completely healed fistula and the internal opening.

Fig. 5.

Photographs of the patient in Fig. 4, a 30-year-old male patient with recurrent right high transsphincteric fistula. (A) Preoperative photograph showing the external opening on the right buttock. (B, C) Immediate postoperative photographs. (B) The final transanal opening of the intersphincteric space (TROPIS) wound inside the anal canal. (C) Final picture after surgery. A drainage tube in the right high transsphincteric tract can be seen sutured to the skin. This photograph was taken at 3 months postoperatively, after the TROPIS wound (internal opening) had healed completely.

Fig. 6.

A 60-year-old male patient with a high intersphincteric posterior horseshoe abscess. He was managed definitively in the first surgery by the transanal opening of the intersphincteric space (TROPIS) procedure. The patient had clinically healed at 3 months postoperatively, and magnetic resonance imaging (MRI) showed that the fistula had completely healed. (A) Schematic diagram of the axial section. (B) Schematic diagram of the coronal section. (C) Preoperative MRI of the axial short inversion time inversion recovery sequence (STIR) section, showing an intersphincteric posterior horseshoe abscess with a high internal opening at the midline posteriorly (arrows, fistula tract). (D) Preoperative MRI of the coronal T2 section, showing a high intersphincteric posterior horseshoe abscess (arrows, fistula tract). (E) Postoperative 3 months MRI of the axial STIR section, showing a completely healed abscess (and fistula) and the internal opening. (F) Postoperative 3 months MRI of the coronal T2 section, showing a completely healed fistula and the internal opening.

Fig. 7.

Photographs of the patient in Fig. 6, a 60-year-old male patient with a high intersphincteric posterior horseshoe abscess. (A) Intraoperative photograph showing insertion of a curved artery forceps into the fistula tract in the intersphincteric plane through the internal opening. The mucosa and the internal sphincter were incised over the forceps. (B, C) Immediate postoperative photographs. (B) The final transanal opening of the intersphincteric space (TROPIS) wound inside the anal canal. (C) Final picture after surgery. A drainage tube can be seen on each side of the horseshoe abscess. This was taken after the TROPIS wound (internal opening) had healed completely after 3 months.