A new method for evaluation of perianal fistula: digital infrared thermal imaging.

Abstract

Listen

Translate article

Perianal fistula is an abnormal hollow tract between the perianal skin and anal canal, which is lined with granulation tissue. Most perianal fistulas are thought to arise as a result of cryptoglandular infection. The exact prevalence is unknown, and the incidence of perianal fistula developing from an anal abscess can reach 38 % [1]. The preoperative determination of the course of perianal fistula canal is of key importance. Parks’ classification system [2] is the one of the most commonly used for anal fistula and defines four different types of fistula: intersphincteric, transsphincteric, suprasphincteric, and extrasphincteric. Determining of the course of the fistula and any side tracks in relation to the anal sphincter and the position of the internal opening can be challenging, and failure to correctly identify the fistula anatomy may result in disease recurrence or damage to the anal sphincter. There are some helpful diagnostic tests such as fistulography [3], anorectal endosonography [4], and magnetic resonance imaging [5], which may guide the management of perianal fistula. Usually, the internal opening of a fistula is narrowed, small, or even periodically closed. The surgeon may encounter difficulties in evaluation of a fistula with an atypical course, and a blind search during surgery may result in false tracts and unnecessary extension of the surgical field. Excessively aggressive surgery may lead to damage of the anal sphincters and cause fecal incontinence, and excessively conservative procedures may lead to recurrence. Therefore, incomplete determination of the course of a perianal fistula is associated with unsuccessful surgical management. Moreover, difficult anatomic conditions limit aggressive diagnosis and therapy, both before and during surgery due to concerns about sphincter damage. For these reasons, we tried digital infrared thermography a new method of diagnosing perianal fistula using ThermaCAM E45 (FLIR, Boston, MA, USA). Our patient was a 42-year-old male diagnosed with perianal fistula with external orifice at the 3 o’clock position, 4 cm from the anal verge. The patient was evaluated in the lithotomy position, and the first thermal image was taken at steady state. It revealed the external orifice and anus clearly (Fig. 1). Five mL cold saline solution (?4 C) was instilled through the external orifice via a cannula, and then, the second thermal image was taken. Thermal changes were detected on the perianal skin extending from external orifice to internal orifice in the anus (Fig. 2). These changes were interpreted as a fistula tract. Thermal visibility of the tract was lower above the external sphincter complex. This image suggested that fistula tract was deeper at this level and transsphincteric. The fistula tract was probed by stile wire, which is compatible with thermal imaging. Fistulectomy with seton treatment was performed. Three months after the procedure, there was no recurrence. Digital infrared thermal imaging is a new, noninvasive, safe, and reliable technique in the assessment of perianal fistula in clinical practice. This technique makes it possible to determine whether the fistula is superficial or deep. It may assist the surgeon during the operation delineating the fistula tract anatomy and identifying the internal orifice, supporting the preoperative and preoperative planning of definitive and appropriate surgical therapy. We are eager to share the results of our ongoing study after its completion. In coming years, we believe that this imaging technique will play an important role in the evaluation of perianal fistula. & I. S. Sarici isamilsarici@hotmail.com