**1. Introduction**

Anal fistulas, especially complex anal fistulas, still present a challenge for surgeons because of their high recurrence rate, possible postoperative risk of fecal incontinence and also the fact that nowadays we still do not have a standardized procedure of choice for treatment.

An anal fistula is defined as an abnormal communication between perianal skin and anal canal, filled with granulation and fibrotic tissue that supports chronic inflammation, disabling spontaneous healing. Most fistulas are of cryptoglandular etiology, but can also be associated with inflammatory bowel disease (Mb Crohn), malignancies, trauma, pelvic sepsis or diverticulitis. Incidence of the disease is about 10 cases per 100,000 individuals with a male to female ratio of 2:1 [1, 2].

In the past, various classifications for anal fistulas were proposed. One of the most widespread classifications was Parks' classification which classified fistulas according to their correlation with anal sphincter complex and divided fistulas into intersphincteric, transsphincteric, suprasphincteric and extrasphincteric [3].

Surgeons noticed, using traditional surgical techniques such as fistulotomy, fistulectomy or cutting seton, frequent continence disturbance following operations, especially in cases when fistula tract passed through deeper parts of sphincter complex and internal fistula opening was positioned more proximally in the anal canal.

To simplify classification and to prevent possible postoperative continence disturbance, colorectal surgeons nowadays mostly use simple classification which divides fistulas into two groups: simple and complex, according to the relation of the proportion of the anal sphincter mechanism they pass through. The classification that distinguishes simple and complex anal fistulas helps the surgeon to avoid using traditional techniques to prevent possible continence disturbance, but does not help in the decision which operative technique is best to use in the treatment of complex fistulas. Classification by Garg is extrapolated from multiple clinical scenarios and presents a better correlation with an actual patient case (**Figure 1**).


## **Figure 1.**

*Garg classification of anal fistulas (with permission of Dr. Pankaj Garg).*

*Anal Fistula: Contemporary View of Complex Problem DOI: http://dx.doi.org/10.5772/intechopen.102752*

Simple anal fistulas have only one tract that crosses less than 30% of the anal sphincter complex and can be treated by fistulotomy or fistulectomy with very low postoperative continence disturbance incidence and high healing rate.

All other fistulas are classified as complex. These fistulas cross the anal sphincter at a point that encompasses more than 30% of the external anal sphincter. They can have multiple tracts. Complex fistulas also include those about inflamatory bowel disease (IBD), those which are anteriorly positioned in female patients or those which are recurrent. If those fistulas are treated with fistulotomy or some other traditional technique, it can result in some type of postoperative fecal incontinence. The average rate of continence disturbance, such as flatus or liquid stool leakage following fistulotomy, was observed in 20–25% cases and up to 12% cases after cutting seton treatment [4, 5]. This effect on continence has resulted in traditional surgical techniques being less favorable for complex anal fistulas treatment and the incentive to use minimally invasive sphincter sparing techniques is increasing.

In anal fistula treatment, it is important to apply an appropriate surgical approach to obtain the best postoperative results such as high primary healing rate, low postoperative pain, low risk for any type of fecal incontinence, low recurrence rate and to subsequently increase postoperative patient's life quality.
