Introduction
“Fistula” means pipe or tube in Latin [
1]. Anal fistula is an abnormal tract that connects the primary opening of the infected gland in the rectum and the secondary opening of the drainage site in the skin of the perianal area [
2]. In more complex cases, secondary tracks may branch from the primary track. Such condition is characterized by chronic purulent drainage or cyclical pain associated with abscess re-accumulation followed by intermittent spontaneous decompression [
1]. Anal fistula patients complain of drainage, bleeding, pain with defecation or sexual activity, and swelling [
3].
Anal fistula fails to heal spontaneously [
4]. Optimal management of anal fistulas involves draining local sepsis, eradicating the primary fistula opening and any associated tracts and secondary openings, preserving the anal sphincter function, avoiding recurrence, and allowing the patient to return to normal activity early. Such objectives pose a challenge to surgeons [
2].
We aimed to report a minimally invasive method by using a novel device to treat anal fistula. In particular, the proposed invasive method may enable surgeons to deal with this troublesome issue with great success.
Materials and methods
From August 2008 to November 2009, 14 anal fistula patients, including 2 females and 12 males, consecutively underwent surgery using the proposed technique and the novel device (Fig. 1). The age of the patients was 35.5±12.9 years old, ranging from 20 years old to 60 years old. Eight patients had simple anal fistula, whereas six had complicated anal fistula. Complicated anal fistula includes two or more fistulas or a long, curved anal fistula. The patients involved in this study underwent surgery for the first time and were informed about the material and technique to be used. Accordingly, patients provided written informed consent.
The exclusion criteria for selecting the patients included pregnancy, diabetes, inflammatory bowel disease, anorectal tumors, tuberculosis, immune deficiency, hydradenitis suppurativa, pilonidal sinus disease, congenital abnormalities, sexually transmitted diseases, rectovaginal fistulas, rectovesical fistulas, anovaginal fistulas, uncomplicated fistula curable by simple fistulotomy, and history of incontinence.
The surgery was performed in all patients using a standard technique described in the latter part of the paper. All patients were under observation for 36 months.
Surgical procedures
Step 1 All procedures were performed under spinal anesthesia. The position of each patient on the operation table varied depending on the location of the fistula.
Step 2 The primary fistula opening was identified. If needed, methylene blue dye mixed with hydrogen peroxide was injected into the external opening of the fistula to identify the internal orifice. Thereafter, a probe was gently inserted into the external opening and was removed from the anal canal through the internal opening. A V-shaped incision was created at approximately 1.5 cm from the anal margin to completely eradicate the internal opening (Fig. 2). Precautions were followed to avoid damaging the anal sphincter.
Step 3 Along the line of the probe, the tool-holder was introduced through the external secondary orifice progressing toward the internal orifice. The probe was removed when the tool-holder was correctly placed. The head protruding from the internal opening was fixed with mill. The power was switched on. An axial circular rotational movement was generated by means of an electromotor rotation at 360 rpm. The surgeon pulled the mini-electromotor and extracted the fistula tract beginning from the primary orifice up to the secondary orifice. Subsequently, the necrotic or granulation tissue inside the fistula tract was completely excised (Fig. 3). If required, the mill was replaced according to the diameter of the fistula tract. The excised tissue was histopathologically examined. One or more small incisions were made between every curved fistula, and the remaining steps mentioned above were then followed.
Postoperative course and follow-up
Antibiotics were administered to all patients every 24 h. Medication was discontinued after 72 h. The patients were discharged when they could manage the wound as outpatients. In particular, the patients were instructed to do the following: restrict physical and sexual activities for three weeks after the operation; have a clear liquid diet for 72 h; and use sitz baths 3 to 4 times a day as needed for comfort and after bowel movements. If necessary, stool softener and oral analgesia were taken. During the first 14 postoperative days, the wound dressings of the patients were changed once a day, and deep packing with povidone iodine-soaked gauze was applied into the wound following a sitz bath.
All patients were followed-up daily until full closure of their fistula tract was achieved. Three follow-ups were made annually via telephone interview. At that time, the premature skin closure of the wound or excess granulation tissue was treated. Recurrence occurred if a discharge or abscess emerges in the same area or if obvious evidence of fistulation occurred at any time during follow-up. Incontinence was present if the following symptoms were observed: any noticeable difficulty in controlling flatus, soiling of undergarments, and accidental bowel movements persisting for more than one month after the operation [
5].
Statistical analysis
Healing time was the period from the date of operation to the date of complete healing. Complications and recurrence among patients were recorded. Data were expressed as mean±standard deviation. All statistical analyses were performed using SPSS 12.0 for Windows.
Results
The average hospital stay of patients was 6.71±1.07 d, and the healing time was 41.43±6.10 d. Recurrence was found in one patient who failed to insist on dressing change. All the other 13 patients achieved successful closure of their fistula tracts. None of the patients had any interference with continence, and no major intra- and post-operative complications were identified.
A typical case
As depicted in Fig. 4, a patient presented a complicated anal fistula preoperatively with two external orifices. The first orifice was situated at five o’clock of the lithotomy position, at 8 cm from the anal margin. Meanwhile, the second orifice was at nine o’clock of the lithotomy position, at 4 cm from the anal margin. The wound completely healed without obvious scarring six weeks after surgery.
Discussion
Surgical treatment for anal fistula involves a balance between eradicating the fistula and maintaining continence. Hence, a novel sphincter-preserving technique is required to manage anal fistulas, for which setons, advancement flaps, fibrin sealant, and bioprosthetic fistula plug are always selected. However, disadvantages of using these modalities, such as long recovery periods and high recurrence and incontinence rates, are frequently reported [
1,
2,
6–
11].
The proposed technique aims to remove the immature granulation tissue, inlaying the epithelium and fibrosis from the tract to facilitate the obliteration of the lumen by well-vascularized healthy granulation tissue. The granulation tissue is removed from the tract by using a mill rather than by opening the entire length of the tracts. Consequently, the new technique generates minimal tissue trauma to the sphincter muscle, thereby leading to reduced bleeding, rapid healing, prevention of inadvertent anal incontinence, and absence of ugly scars. The proposed approach is a new, simple, minimally invasive, and effective technique for treating anal fistulas. The superiority of this new material is more obvious when the fistula is longer. This method is an encouraging step in the treatment of the notorious disease.
Attention should be given to the following details when the new method is applied.
First, the importance of accurately characterizing the fistula tract prior to therapy cannot be overemphasized. Careful palpation with the index finger in the anal canal and with the thumb exterior to the canal is adequate in most patients with simple fistulas; such method may identify the fistulous track as a cord-like lesion under the skin [
1]. Meanwhile, for patients with a more complex fistula, the fistulous track should be subjected to imaging techniques, such as contrast fistulography, anorectal endosonography, computed tomography, or magnetic resonance imaging. The exact choice of modality depends on local expertise, cost, and available equipment [
12–
21].
Second, as the infection of glands within the submucosa and internal sphincter is the initiating event in fistula-in-ano through a process known as the “cryptoglandular hypothesis” [
22], the eventual eradication of the fistula depends only on identifying and eliminating the internal opening [
23]. The lateral traction on the fistula tract sometimes results in dimpling at the primary opening. The delicate intra-operative probing of fistula tract may be more useful; but probing should always be gently performed. Otherwise, a false route will easily form, further complicating the operative procedure. Injecting various substances, such as methylene blue, indigo carmine, hydrogen peroxide, or even milk, has been described and widely used if the internal orifice is not determined by probing. The contamination of the operative field can be avoided by injecting hydrogen peroxide, which is probably the best means of identifying the internal opening because the pressure generated by the bubbles may be sufficient to penetrate even a stenotic tract [
6,
24–
27]. When the internal opening has been identified, the internal opening must be eradicated.
The preliminary results obtained thus far are encouraging despite the limited number of cases and short follow-ups. Future research must provide definitive evidence of the advantages of the proposed new technology by conducting a randomized controlled trial.
Higher Education Press and Springer-Verlag Berlin Heidelberg
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