Anal fistula is a common disease in anal surgery. Fistulas are difficult to heal spontaneously and most require surgical treatment. The goal of fistula treatment is to remove the fistula orifice and all interconnecting epithelialized fistulas and to minimize sphincter damage, and fistula healing and preservation of anal function should be considered key indicators of treatment.
The American Society of Colorectal Surgeons (ASCRS) 2005 guidelines for the treatment of fistulas clearly state that if fistula surgery significantly affects the patient’s postoperative anal function, it should be treated with line drainage.
The concept of “fistula survival”, the domestic use of “floating line” drainage and the “Clinical Guidelines for the Treatment of Anal Fistula” jointly developed by the Colorectal Surgery Group of the Chinese Medical Association, the Chinese Society of Traditional Chinese Medicine, and the Committee on Colorectal Diseases of the Chinese Society of Integrative Medicine. Guidelines for the diagnosis and treatment of anal fistula (2006 edition), and the statement of the Association of Colorectal Societies of Great Britain and Ireland (ACPGBI) on the treatment of anal fistula, are all motivated by the same considerations. In the light of developments in fistula treatment, the protection of anal function has become increasingly important.
The 2011 edition of the ASCRS guidelines includes in the category of complex fistulas any postoperative fistula that predisposes to anal incontinence, including fistulas that cross 30%-50% of the external anal sphincter (high intersphincter, above the sphincter, and outside the sphincter), anterolateral fistulas in women, recurrent fistulas, fistulas with anal incontinence, fistulas after local radiation therapy, fistulas with Crohn’s disease, and fistulas with multiple fistulas. It should also be noted that both the fistula itself and the fistula surgery may significantly affect anal bowel control.
Confirmation of the internal opening and fistula course is important for surgical treatment
In addition to visualization and palpation, the Goodsall rule accurately predicts the location of the internal orifice in 49-81% of patients, but the course of the fistula is not easily determined, especially in patients with long fistulas, recurrent fistulas, and Crohn’s disease. The accuracy of hydrogen peroxide and methylene blue injection into the external orifice exceeds 90% and 80%, respectively.
For complex fistulas, the choice of imaging is very helpful in determining the internal orifice, secondary fistulas and abscesses, as well as clarifying the relationship between the fistula and the sphincter complex, such as magnetic resonance imaging (MRI), endorectal ultrasound (EAUS) or ultrasound endoscopy (EUS). It has been replaced by MRI. About 80% of fistulas are secondary to infection of the anal saphenous fossa, and the possibility of Crohn’s disease, trauma, radiation therapy, malignancy, or specific infections should be considered for fistulas in specific locations or presentations.
Procedure of anal fistula
No single technique is suitable for all fistulas, and the advantages and disadvantages of cure rate, extent of sphincter dissection, and degree of anal function damage should be weighed to develop an “individualized” treatment plan.
Finally, the following should be noted in the treatment of anal fistula: 1. cherish the opportunity for a small number of patients to heal themselves through perianal abscess incision and drainage; 2. promote “minimally invasive” fistula treatment throughout the entire process, and minimize surgery to sever the sphincter.
There are many different types of anal fistula procedures, which can be broadly divided into the following according to the impact on the sphincter.
1) Sphincterotomy
fistulotomy
Anal fistula excision
I-stage suturing after excision
suturing
2)Sphincter preservation
Fistula excision
anterior migration of rectal mucosal flap
Hanging wire drainage
tunneled branched towline
fistula debridement and fibrin glue injection
Fistula plug tamponade
Ligation of inter sphincter fistula (LIFT)
inter sphincter fistula ligation + fistula plug (LIFT-plug)
Video-assisted anal fistula treatment (VAAFT)
In general, simple fistulas can be treated with fistulotomy, fistulotomy, suturing, fistula debridement and fibrin glue injection, and fistula plugging. Complex fistulas can be treated with fistulotomy and staged fistulotomy, tunneled branched dragline, fistula debridement + fibrin glue injection, fistula plug, anterior migration of rectal mucosal flap, intersphincteric fistula ligation (LIFT), and intersphincteric fistula ligation + fistula plug (LIFT plug).