Video-assisted anal fistula treatment (VAAFT) combined with ozonide oil dressing: standardization of technique in pediatric patients

All patients who underwent VAAFT between August 2018 and May 2023 in two divisions of Pediatric Surgery were enrolled in the study. Exclusion criteria were patients who had already received primary surgery for anal fistula, such as fistulotomy, fistulectomy, and cutting seton placement. Inclusion criteria encompassed all patients who underwent VAAFT, whether it was the primary procedure or a secondary intervention after prior incision and drainage of perianal abscess.

Surgical contraindications were fistula with recent inflammation (immature track), pelvic fistula (diagnosed by magnetic resonance), and no active discharge for at least 2 months.

Demographics, clinical features, pre-operative imaging, surgical details, postoperative outcome, and medium-term follow-up data were retrospectively reviewed for each patient. Postoperative pain was assessed using the Visual Analogue Scale (VAS). To enhance the reliability of pain assessment in infants and young children, an independent observer applied the Visual Analogue Scale (VAS). Conversely, older children, who were able to collaborate, actively participated in evaluating their postoperative pain using the VAS.

The study received appropriate Institute Review Board (IRB) approval.

Thirty-three procedures were performed in 30 patients over the study period. The male/female ratio was 23/7 (3.3). The median patient age was 5.7 years (range 1.75–14). Anal fistula was idiopathic in 26/30 (86.6%), iatrogenic in 2/30 (6.7%), who had previously received anorectal surgery for Hirschsprung’s disease, and secondary to Crohn’s disease in 2/30 (6.7%).

Complex fistulae, defined as those with more than a single tract connected to the internal opening, were identified in 3/30 (10%) patients.

VAAFT served as the initial surgical procedure in 21/30 (70%), while it was employed as secondary surgery following prior incision and drainage of perianal abscess in the remaining 9/30 (30%).

The median duration of surgery was 23 min (range 18–40). No intraoperative complications occurred. All patients received ozonide oil dressing twice a day for median 4 weeks postoperatively. The median postoperative pain score, assessed using VAS [score range 1–10], was 3.2 (range 1–5). Pain therapy was limited to the first postoperative day with intravenous paracetamol 15 mg/kg 8 hourly for all inpatients. None of the patients required supplementary pain therapy. No postoperative complications were observed. The median hospital stay was 24 h (range 9–36). The median healing time was 28 days (range 17–39) (Fig. 3).

At median follow-up of 2 years (range 0.5–5), disease recurrence occurred in 3/30 (10%) patients with idiopathic fistula, who were re-operated using the same VAAFT technique, with no further recurrence. No fecal incontinence or soiling was observed.

Patient characteristics and outcomes of VAAFT are summarized in Table 1.

Surgical procedures for anal fistula have 3 main objectives: identification of fistula’s track and its internal opening, excision of fistula’s track, and preservation of anal sphincter function. Traditional surgical procedures for anal fistula included fistulotomy for superficial fistulae, fistulectomy for complex and deep fistulae, and staged fistulotomy with cutting seton placement for high fistulae [5, 7]. These procedures were associated with high postoperative morbidity, long time of wound healing, and need for regular painful dressings change [11]. Fecal incontinence was a significant complication in these patients, especially in complex and recurrent fistulae [13, 14]. Placement of draining seton alone was described as a viable treatment option for definitive symptomatic management of anal fistulae [9]. However, this treatment option was associated with disease recurrence in 7% and need for additional procedures in 27% of treated patients [9].

The video-assisted anal fistula treatment (VAAFT), first described in adults by Meinero and Mori in 2011 [19] and in pediatrics by Pini Prato in 2016 [22], relies on the principles of excision, cleaning, and fulguration of the fistula’s main and secondary tract(s) and identification and safe closure of the internal fistula opening to achieve the complete healing of the fistula. The innovation of the VAAFT is the precise identification of the fistula anatomy and the internal fistula opening using the fistuloscope and the fulguration of the fistula’s tract walls under direct vision using a monopolar electrode. There are no surgical incisions since surgical access is obtained via the pre-existing external opening of the fistula. The 10-Ch fistuloscope with 8° viewing angle allows to identify all side tracts of the fistula and any endoanal or endorectal orifices. Closure of the internal fistula opening is an essential step of the procedure to dramatically reduce the risk of disease recurrence. Pini Prato et al. [22] reported 100% success rate for those patients who underwent a complete VAAFT. Conversely, persistent anal fistula was observed in two patients who underwent diagnostic fistuloscopy without complete VAAFT and recurrence in one of the patients who underwent fistuloscopy and electrocoagulation without mucosal sleeve closure of the endorectal opening. Visualization of the fistula tract and its branches facilitates the precise identification of the course of the fistula and its internal opening. This capability is crucial in preventing the inadvertent creation of a false tract or false internal opening that may occur when blindly and forcefully exploring the tract with a fistula probe.

Closure of the internal opening in VAAFT can be accomplished using various methods, such as a mucosal sleeve, interrupted stitches, or a purse-string suture. The selection of the method is primarily depending on the surgeon’s preference and anatomic factors. If the orifice is narrow or partially concealed, interrupted stitches, or a purse-string suture might be adequate for closure. In cases with large or multiple internal openings, a mucosal sleeve may be necessary. We did not observe any difference between the two methods in the outcomes.

When faced with challenges in identifying the fistula internal opening by probing, employing the hydrodistension effect of the fistula tract and using trans-illumination with the light from the fistuloscope passing through the bowel wall can be beneficial. Alternatively, injecting hydrogen peroxide, methylene blue, or more recently, indocyanine green (ICG) through the external orifice may assist in visualizing the internal opening in most cases. If these methods, including trans-illumination, prove ineffective in localizing the internal fistula opening, the recommended course of action is limited to the fulguration and debridement of the fistula tract.

The results of our series demonstrated that this technique is feasible and safe in children. It just requires a short admission. Additionally, VAAFT is versatile in its application, suitable for addressing both simple and complex fistulae. Also, Crohn’s anal fistulae can be effectively treated using this technique. The procedure can be successfully repeated in case of recurrent fistulae after VAAFT. Moreover, it can be utilized across a wide age range, from infancy to adolescence.

In our series, with a median follow-up of 2 years, the results were very satisfactory, leading to 90% success rate and 10% recurrence rate. A crucial issue in the surgical treatment of complex anorectal fistulae is to provide high rates of definitive closure without significant impairment of fecal continence. VAAFT allowed to avoid this issue. None of our patients developed postoperative fecal incontinence or soiling.

We believe that the standardization of the surgical technique is an essential factor contributing to the success of the procedure. Following meticulous examination of video recording of all VAAFT procedures, we established standardization of VAAFT in 5 separate steps: (1) Initial diagnostic assessment; (2) Fistuloscopic exploration of the fistula track; (3) Identification of the internal fistula opening and/or secondary tracks; (4) Fulguration of the fistula track under direct vision; and (5) Closure of the internal fistula opening. Regarding the learning curve, it can be shortened if the operating surgeon has previous experience with endoscopic surgery. In any case, we believe that at least 10–15 procedures are necessary to master the technique.

Another key point of the procedure is to use the specific technical equipment needed for VAAFT. It requires initial costs to purchase the VAAFT instrumentation. However, the fistuloscope and accessory instruments are reusable, thus the initial costs are likely to be recovered soon. Additionally, there are significant advantages to patients such as reduced pain, absence of perianal wounds, no needing for painful dressings, fast recovery, and early return to daily activities. Balaz et al. [11] reported a duration of hospitalization ranging from 2 to 30 days in different patient groups undergoing fistulotomy. Conversely, in our VAAFT series the median hospital stay was 24 h.

A crucial point for successful outcome of patients operated for anal fistula is the postoperative wound care. The key clinical priorities for postoperative care of high anal fistulae are to keep the perianal area clean, to ensure unobstructed drainage of the incision and to avoid bridge-type healing. Studies have shown that dressing changes was the most painful part of the wound recovery process in many patients [20, 23].

We proposed a simple method of dressing, which significantly reduced the pain of patients and was learned quickly by parents, reducing the time of hospitalization and the number of patients coming to the clinic for dressing change. The most important part of this dressing is the use of ozonide oil. The oil formulation allows the ozone to be stabilized in an olive oil matrix. Stable ozonides act on the wound healing through different pathways: antibacterial, antiviral, and antifungal action; carrier action of native O₂; antioxidant action; modulation of the inflammatory phase; and promotion of angiogenesis [24, 25]. To increase the therapeutic effect, it is worth to inject the product directly within the fistula cavity. The rationale of intralesional application of the ozonide oil was based upon the observation that the ozonated composition exhibited the capability to deliver nascent oxygen deep within the lesion, promoting accelerated healing, while avoiding irritation to the skin and mucosa [26]. Our dressing method was painless as it avoided using adhesive tape or dry gauze which could stitch to the wound. The oil formulation was easier to manage and apply directly into the fistula track by inserting the tip of a syringe through the external orifice. This maneuver was painless, as observed during dressing change by either nurses or parents/caregivers. It is crucial that parents strictly adhere to the wound protocol. They must keep clean the perianal area and change the dressing after each evacuation until the completion of wound healing.

The main limitations of the present study are the relatively small series, the retrospective nature, and the lack of a control arm. Future prospective follow-up studies are necessary to better address the advantages and shortcomings and long-term efficacy of the technique.

Our series confirmed that VAAFT is a safe and effective technique to treat children with perianal fistula. The technique is versatile, allowing to treat fistulae of different etiologies. Postoperative course was painless and fast. Future comparative prospective studies are needed to better establish these conclusions.