Gloria Zaffaroni interviews Carlo Ratto, Associate Professor in General Surgery at the Catholic University in Rome and Chair of Proctology Unit, Fondazione Policlinico Universitario 'A. Gemelli', IRCCS, Rome, Italy.

Even if anal fistula is an illness well known since ancient times, there is no gold treatment among the various surgical procedures. The treatment remains challenging, mainly due to variability in success and recurrence rates as well as continence impairment risks.
Advances in surgery and technology have led to various minimally invasive approaches, but results, in terms of success rate and recurrences, are still quite disappointing.

Today, as well as seven centuries ago, fistulotomy remains the most frequently used therapeutic option that might guarantee the highest success rate. However, the sacrifice of the anal sphincters often leads to various degrees of postoperative incontinence. For this reason, there has been a negative trend in the use of a traditional fistulotomy over the years.

Parkash first described fistulotomy plus end-to-end primary sphincteroplasty for the treatment of complex anal fistulas in 1985; however, this procedure still tends to be regarded with skepticism due to the lack of clear scientific evidence about the risk of postoperative fecal incontinence.

The surgical technique includes either a fistulotomy or a complete fistulectomy of the primary tract, from the external to the internal opening, with section of both anal sphincters below the fistula. The internal opening is removed at the level of the mucosal surface. The reconstruction phase included end-to-end sphincteroplasty or, less frequently, an overlapping. Finally, anal mucosa and submucosa are closed. The external part of the perianal wound could be left open to permit serum drainage.

Gloria Zaffaroni: Dear Professor Ratto, thanks for the opportunity to talk and focus on fistulotomy and fistulectomy with sphincteroplasty, for the monthly topic of ESCP anal fistula.

Do you think the easiest solution (fistulotomy and fistulectomy) could be considered the most dangerous and why?

Carlo Ratto: Theoretically, yes! Theoretically, because making a fistulotomy or fistulectomy alone provides to lay open or excise, respectively, the fistula tract. In particular, during fistulotomy also the sphincter(s) below the fistula tract is(are) incised. Classically, the wound is left open, healing by a 'second intention' scarring process. Consequently, if the sphincter muscle spared from the procedure will result functionally insufficient, the patient can complain of some degree of continence impairment up to a frank fecal incontinence. This risk, in the literature, ranges from 6% to 28% in low fistulas, and from 17.5% to 40% in high fistulas. Moreover, also sort of 'pseudo-incontinence' can affect the patient after fistulotomy. However, on the other hand, we must take in account that fistulotomy/fistulectomy provide a very good opportunity to cure the anal fistula, ranging from 85% to 98% of patients.

GZ: How can we reduce the risk of incontinence? Choosing a fistulotomy vs a fistulectomy? Or preferring one technique in the sphincteroplasty?

CR: Using fistulectomy (with the 'core out' technique) only the sphincter muscle immediately adjacent to the fistula tract is at risk of significant damage. So, if this damage is estimate as not significant, this approach could be preferred to fistulotomy. However, this evaluation is frequently not easy, and the continence impairment can be a real disappointing result. In addition, the fistula healing rate after fistulectomy seems slightly lower than following fistulotomy. As long as the sphincter muscle to be sacrificed is not too much (not more than 50% of the external anal sphincter length could be a good cutoff), we could choose the fistulotomy (with partial or total excision of the fistula wall) but providing an immediate repair of the incised sphincters.

GZ: Can you tell us more about this technique in patients at risk for fecal incontinence (as anterior fistula in women, recurrent fistula, or history of fecal incontinence)?

CR: Anterior fistula in women and history of fecal incontinence should be regarded as contraindication for any kind of sphincter damage in treating an anal fistula, including the fistulotomy with primary sphincter repair, while a recurrent fistula requires a careful evaluation of the anal function (by endoanal ultrasound or MRI, and anal manometry) in order to assess the possible risk of continence impairment due to a fistulotomy. However, if this approach could be estimate as safe, I would definitely prefer to repair the layed open sphincters.

GZ: What do you mean by 'pseudo-incontinence'?

CR: Everyone has experienced that following fistulotomy alone the most frequent sequela is the 'key hole' aspect of the anus, meaning that the scarring process of the lay open procedure has left a keratinised gap along the area of sphincter incision. Of course, the sphincter contractility is highly reduced at that level, and the scar tissue has lost the best sensibility function. Consequently, at the end of fecal evacuation, some small amount of feces can remain entrapped in this anal ravine, not felt by the patient, ready to go out after the end of evacuation, giving the patient the frustrating sensation of an incontinence, similarly to what occurs with soiling and passive incontinence. Managing this condition is far from simple.

GZ: How can we manage the sphincter dehiscence?

CR: Sphincter dehiscence following fistulotomy with primary sphincter repair can occur in a mean of less than 3% of cases (range: 0-8.3%). It leads to a subsequent scarring exactly similar to what happens following a classical fistulotomy. Thereafter, the continence should be evaluated and, if significant, a secondary repair could be attempted. Other options could be considered.

GZ: Can you tell us the additional advantages of the primary sphincter reconstruction?

CR: The major advantages are represents by a very short additional operation time (compared to the fistulotomy alone), the significantly shorter healing rate (even considering the quite frequent dehiscence of the mucosa/skin suture, due to the anal tissue stretching during defecation), the much more comfortable postoperative course (no or very limited number of medications, usually self-made by the patient, very low intensity of anal discomfort/pain), aspect of the anus similar to the normality with optimal functionality (and also appearance); no severe sequelae in the long term.

GZ: In your experience what can you say about patients' satisfaction?

CR: In our last study, recently published on Techniques in Coloproctology (2019;23:993–1001), we have investigated this aspect using a 11-point numeric rating scale (NRS), ranging from 0 (the worst satisfaction) to 10 (the best satisfaction). In 203 anal fistula patients treated with fistulotomy and primary sphincter repair followed up for a mean period of 48.7 ± 14.3 months (range: 18–85). At the last follow up visit, the mean NRS was 9.3 ± 1.6. Investigating with a uni-multivariate analysis the factors significantly influencing the patients' satisfaction we found that the 'de novo' postoperative continence impairment (occurring in 12% of patients, being mainly minor incontinence) was the only factor associated with a lower satisfaction rate.

Our patients with anal fistula request to be free-of-fistula but also to preserve continence. Today, what we, as surgeons, can offer is a quite wide list of options improved by new techniques and technologies. Their efficacy must be measured in term of fistula healing rate and continence preservation: up to these concepts nothing is really new! Real news can come only from a different approach to anal fistulas, where the 'scalpel' will be used as less as possible, and, on the contrary, a different approach, much more fitting the fistula pathophysiology (finally fully understood!), can cure the inflammatory process without any negative effects of the anal sphincters and function.

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