Vittoria Bellato interviews Phil Tozer, Consultant Colorectal Surgeon at St. Mark's Hospital (UK) for ESCP's monthly topic: anal fistula.

Phil Tozer was trained as a general and colorectal surgeon in London with a focus of both his clinical and academic training under Professor Robin Phillips at St Mark's Hospital. His thesis in idiopathic and Crohn's anal and rectovaginal fistula was the beginning of a passionate interest in advanced proctology and IBD. His clinical and academic work continue to focus on these areas at the Fistula Research Unit at St Mark's Hospital.

Vittoria Bellato: Crohn's perianal fistulas are challenging for patients and clinicians. Many do not respond to available treatments and some patients may present with a perianal abscess as first presentation of isolated perianal Crohn's disease.

While the treatment of complex Crohn's fistula is mostly centralised nowadays, almost all general surgeons, at every stage of their career will encounter and treat a perianal abscess and fistula - and management of perianal fistula can vary a lot from centre to centre. [1]

What should a surgeon know before an incision and drainage of perianal abscess and a treatment of perianal fistula?

What are the major risks that a non-proctologist can run into?

Phil Tozer: I think that the general principles are to ensure adequate drainage without damaging muscle, to place comfortable loose setons to control the fistulae and to reassure the treating gastroenterologist that optimised medical treatment can begin as there is no longer any undrained cavity or tract.

Once this has been done and medical treatment is optimised, it is valuable to try to work out whether the patient will remain quite stable on medical treatment following this, or whether their disease continues to progress or cause a great impact on quality of life, or whether their fistula starts to settle and might be suitable for an attempt at repair. We should also be keen to undertake a examination under anaesthesia (EUA) when medical treatment appears to be 'failing', rather than just escalate medical treatment, since an undrained cavity in this setting can hold up progress, and once drained the same drug regime may start to be effective again.

I tend to talk about stomas early on, not because all patients will need them, but firstly because the first time they hear about a stoma shouldn't be when it is required, and secondly because the narrative around stomas is often very negative. They are often considered an intervention of last resort and that they represent 'failure' (which the patient assumes is theirs!). In fact, for some patients a stoma is a positive choice which improves quality of life.

One mistake is to have a patient who says that they wish they'd had their stoma 10 years earlier - and it is perhaps avoided through this early conversation.

Another risk is to hunt for an internal opening (IO) when the tract is unclear, particularly in the acute situation. It is better to retreat and come again another day, rather than create a false passage.

VB: When, in your opinion, should a colleague refer a patient affected from a perianal fistula to a tertiary centre?

PT: This is a very difficult question to answer and it depends very much on the patient and surgeon and gastroenterologist. In general, patients should be referred if there is any doubt as to how best to manage the fistula. A fistula which may be suitable for repair should be referred if the repair technique is not part of the surgeon's tool kit, and a fistula where control cannot be obtained, and quality of life restored may also benefit from a second opinion. There is a danger that patients find themselves stuck in a low quality of life cul-de-sac with setons in and medical treatment just not really helping - a more proactive approach is needed here, to optimise medical treatment and perhaps utilising further surgery to get the whole system completely drained. If this is unsuccessful then defunctioning or proctectomy may be required and some teams may want a tertiary opinion at this point, particularly in younger patients.

VB: At what stage of perianal abscesses and fistulas should we suspect Crohn's?

PT: Great question. We showed (in a piece of work by Kapil Sahnan on HES data in the UK) that 3% of primary perianal abscesses in the UK were diagnosed with Crohn's soon after. This is a golden opportunity to identify these patients before they get too sick.

As well as looking for luminal symptoms of IBD, I'm also interested in family history, proctitis and other aspects of perianal disease. As you said earlier, it's perfectly possible to have isolated perianal Crohn's, and although it is low yield, I will take biopsies looking for granulomas at EUA. If I suspect Crohn's disease, I will either start with faecal calprotectin, or move straight to luminal investigation if my suspicion is high.

VB: Currently there is no guideline for the treatment of patients with Crohn's disease and high perianal fistulas. Many patients receive anti-TNF medication, but no long-term results have been described, nor has its efficiency been compared to surgical strategies. PISA study has taught us how difficult is to conduct a randomise trial in this field. How do you decide whether to opt for surgical, medical or surgery plus medication?

PT: The first step is to work out what is feasible and the second is to understand the patient's goals. Some want healing of their fistula at any cost but most want a more nuanced discussion and some will prefer good symptom control rather than attempts at repair, even if the latter is possible. I aim to align my intent and interventions with the patient's goals as much as possible, explicitly discussing the options and their pros and cons whilst refusing to answer the question 'what is the best option' except with 'only you can answer that', before going through the options again in more detail. What PISA taught us, in my view, is that if we fail to do this the patient will be unhappy even if we technically succeed.

So I start by getting symptom control as good as I can. This usually involves some level of rationalisation of the fistula and control of the surrounding disease aiming for a situation when I can offer an anatomical or non-anatomical repair. Even if they do not want repair, this is the same process that is required to obtain good symptom control.

Some patients never get to this point because their luminal disease is too severe, or their perineum remains hostile and inflamed, or because their fistula is simply not suitable for a repair attempt, and those patients continue to have optimised medical therapy, symptom control surgery as required and I regularly check in with them to see if a stoma would make life better or worse for them.

If I think repair is possible then I will offer them LIFT, flap, FiLaC or cVAAFT if suitable, MSCs within the context of a trial, or the comparator arm of the Admire CD study, probably combined with cVAAFT. Essentially whatever is a suitable operation anatomically.

I think the Getaid group has correctly knocked plugs out of this arena.

VB: Regarding treatment of high perianal fistula, a recent systematic review and meta-analysis suggests that for cryptoglandular fistula overall success and recurrence rates after the advancement flap (AF) and ligation of intersphinteric fistula tract (LIFT) procedure are comparable. [2] How do you choose between LIFT of AF?

PT: In my view, LIFT requires a tract without intersphincteric (IS) complexity, which crosses the IS space relatively straight, with no injury to the internal anal sphincter (often felt as a 'wide IO' or deep, wide cup IO) and with enough space between the tract and the anorectal junction that it can be encircled without injury to the rectum (or vagina if anterior).

Flaps need a relatively high IO so that there is room to anastomose the flap below, and most importantly, adequate mobility of the rectal wall (seen as internal intussusception, usually) such that the flap can be brought down without tension. It is unusual in my experience to find many patients suitable for both but if they were I would probably do a LIFT first.

The downside of the LIFT is really the recurrence which appears in both the interphincteric and transphincteric locations, effectively upstaging the fistula. We still don't know how frequent this is amongst LIFT failures - I estimate it is less than a third of the time. The downside of the flap is the risk of minor continence impairment. Some patients dislike these risks sufficiently to choose a newer technique like FiLaC or VAAFT as a first line, which I'm comfortable with despite more limited evidence, as they tend to have less of a downside.

VB: At which stage of the treatment of a complex Crohn's perianal fistula do you consider the creation of a stoma as an option?

PT: As I mentioned above, I talk about this early and often. I regularly remind the patient that their disease brings their quality of life down and my job is to restore it as best I can. I should say that these conversations regularly happen in a joint consultation, so it's really 'we' rather than I. We will tell them all the options we have to try to improve things for them, discuss the likelihood of success (in their terms) and the potential downsides, the next two or three steps down each road and what the best and worst versions of the future look like in each scenario. A stoma is always one of the options and at some point, some patients take the view that a stoma is now the best option for quality of life improvement and they ask for it.

We need to move away from the idea that we can know what is best for a given patient. I think that Downton is better than Bridgerton, but I might take a different view if I was younger and less of a pedant about language!

You might think this is a facetious example but when choosing a symptom control regime of medical treatment and pVAAFT/EUAs every six months, vs. proctectomy, it is exactly the lifestyle issues about work, sports, sex and so on which are likely to influence the patient's decision, not just the stoma and the risks of pelvic dissection.

The only problem with this view is that patients can't know what they don't know - they cannot feel the potential benefit of defunctioning or proctectomy without having experienced it, and we have to work hard to ensure they have a good idea about this.

This is best done in the hands of stoma nurses and patients of a similar age, gender, sexuality, ethnicity etc. who can relate their own experiences in a way which is meaningful to the patient. When they ask me if I'd have a stoma I tell them that the views and experiences of a married, fat, 40 something man probably carry little value when offered to a 25 year old girl trying to start out in her career, with partners, children and body image on her mind.

We should also be thinking about anal sex if we're considering proctectomy, particularly but not exclusively in gay men. Surgeons are too reticent to talk about sex - patients need and deserve to know what impact our operations will have on their ability to ride a bike, go to work, have kids, and also enjoy sex (amongst all the other parts of daily life we usually take for granted). It's a difficult thing to do, particularly with someone much younger than you, and of course appropriate chaperones or other safeguards are important, but we must not neglect the conversation about sex. I regularly embarrass colleagues with my frank discussion in joint consultations, but I can tell you that I rarely embarrass the patients - they tend to be very keen to talk about sex in most cases, and have not so far been offended (as far as I know) if they shut that line of conversation down.

VB: Crohn's patients with perianal disease are frequently young and the disease impacts heavily on their quality of life. Which type of discussion is fundamental to emphasise when visiting and consenting those patients before surgery?

PT: A complete conversation encompassing all aspects of quality of life is key. I've gone into detail in the last few questions so I won't reiterate too much but we need to find out what is important to the patient in terms of quality of life (what is their work, who do they live with, what do they do for fun, sex, sports, holidays, saddle activities etc.) and tailor the discussion to those issues. This will help them choose the right options for them, and help them to understand the risks of a given treatment. This is the first stage of the consent process and going through and signing the form is the second. I think it is a mistake to view consent as a one part process in the elective setting, and by the time we do the form, I expect the patient to almost be able to fill it in themselves!

VB: Regarding Quality of Life (QoL), another challenging area is the QoL assessment in perianal Crohn's disease. In fact, despite recommendations by a global consensus, there are currently no specific patient-derived quality of life tools to measure response to treatment. Your group has recently published and proposed a new patient reported outcome measure: the Crohn's anal fistula Quality of Life (CAF-QoL). [3] What's new here and why is it crucial to assess QoL in these patients?

PT: CAF-QoL is the disease specific, patient derived QoL score that the ECCO consensus pointed out was missing. Sam Adegbola, one of our research fellows, developed the score with the help of qualitative researchers from Kings who joined us at the FRU for the project. It is a QoL score designed for understanding QoL as it changes along with variations in disease severity, or after an intervention, for example. It can be used to assess the QoL impact of interventions and will hopefully be utilised by perianal Crohn's trials going forwards. It considers the issues which are most important to patients and includes all of the lifestyle issues we've discussed and more! Your readers should find it in Gut [3].

VB: Similar problems arise from the lack of an international unique postoperative outcome assessment of perianal fistulas.

PT: Yes, outcome measurement is one of several sources of heterogeneity in perianal Crohn's disease studies which makes them difficult to compare and understand. Kapil Sahnan, another of our research fellows in the FRU, published a Core Outcome Set which we created as part of the ENiGMA collaborative in the UK. This should standardise a minimum set of outcomes across all future studies, and puts the patient voice at the centre of deciding what success looks like. Classification is the next key step to remove further heterogeneity from clinical trials, and a group of high-volume expert centres in Europe have been putting this together over the last year or so, which we hope will be useful clinically and in research. Watch this space!! [4]

VB: Thank you very much Phil for the exhaustive answers, looking forward to next updates!


  1. Ratto C, Grossi U, Litta F, Di Tanna GL, Parello A, De Simone V, Tozer P, DE Zimmerman D, Maeda Y. Contemporary surgical practice in the management of anal fistula: results from an international survey. Tech Coloproctol. 2019 Aug;23(8):729-741. doi: 10.1007/s10151-019-02051-5. Epub 2019 Jul 31. PMID: 31368010; PMCID: PMC6736896.
  2. Stellingwerf ME, van Praag EM, Tozer PJ, Bemelman WA, Buskens CJ. Systematic review and meta-analysis of endorectal advancement flap and ligation of the intersphincteric fistula tract for cryptoglandular and Crohn's high perianal fistulas. BJS Open. 2019 Jan 21;3(3):231-241. doi: 10.1002/bjs5.50129. Erratum in: BJS Open. 2020 Feb;4(1):166-167. PMID: 31183438; PMCID: PMC6551488.
  3. Adegbola SO, Dibley L, Sahnan K, Wade T, Verjee A, Sawyer R, Mannick S, McCluskey D, Bassett P, Yassin N, Warusavitarne J, Faiz O, Phillips R, Tozer PJ, Norton C, Hart AL. Development and initial psychometric validation of a patient-reported outcome measure for Crohn's perianal fistula: the Crohn's Anal Fistula Quality of Life (CAF-QoL) scale. Gut. 2020 Dec 3: gutjnl-2019-320553. doi: 10.1136/gutjnl-2019-320553. Epub ahead of print. PMID: 33272978.
  4. Machielsen AJHM, Iqbal N, Kimman ML, Sahnan K, Adegbola SO, Kleijnen J, Vaizey CJ, Grossi U, Tozer PJ, Breukink SO. The development of a cryptoglandular Anal Fistula Core Outcome Set (AFCOS): an international Delphi study protocol. United European Gastroenterol J. 2020 Mar;8(2):220-226. doi: 10.1177/2050640620907570. PMID: 32213065; PMCID: PMC7079265.
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