Clinical and technical evidence

A literature search was carried out for this briefing in accordance with the published process and methods statement. This briefing includes the most relevant or best available published evidence relating to the clinical effectiveness of the technology. Further information about how the evidence for this briefing was selected is available on request by contacting

Published evidence

This briefing includes 4 single-centre, non-controlled studies involving 704 patients with anal fistulae. These studies were selected because they represent the highest quality evidence and included the largest number of patients. The results indicate that VAAFT is safe, effective and associated with a low morbidity. In the studies VAAFT was mostly done as a day-case procedure.

Treatment with VAAFT may lead to fistula recurrence rates of up to 30%. The study authors speculated that, in some of the studies, recurrence may have been because of the learning curve of the surgeons and the type of fistulae treated. Because of the relatively low morbidity resulting from the procedure, some patients had VAAFT several times.

The case study by Liaqat et al. 2016 (not included in the table below) is the only report identified about the use of VAAFT in children and describes its successful use in a 6-year old girl. No recurrence was reported and the follow-up period is unknown.

Table 2 summarises the clinical evidence as well as its strengths and limitations.

Overall assessment of the evidence

The evidence base for VAAFT is still developing and comprises non-comparative and case studies. The total number of patients reported on is small in the context of a new procedure with a recognised learning curve.

The long-term healing rates for VAAFT are not addressed by the current evidence, because follow-up was either too short or completed in too few patients.

Most studies did not evaluate faecal continence; only Kochhar et al. (2014) used anal manometry to assess sphincter muscle strength before and after VAAFT.

All studies reported that pain scores and complication rates were low, suggesting that VAAFT is safe and well tolerated by patients.

All of the studies were done outside of the UK, which might limit their generalisability to NHS practice.

Table 2: Summary of evidence


Details of intervention [and comparator]


Strengths and limitations

Chowbey et al. 2015


Uncontrolled open-label study

Single centre


VAAFT (n=416), fistulotomy for superficial subcutaneous fistulae (n=114), LIFT with fulguration of distal fistula tract (n=21), incision and drainage of abscess only (n=29).

Internal fistula opening could not be found in 101 people and was too high to reach in 5 people.

391/416 procedures were done as day cases. 7 people were readmitted due to bleeding from the rectum or fistula tract.

Mean VAS score (0–10) was 3.1 at discharge and 1.6 after 1 week.

Discharge from the external fistula opening was found in 87% of people after 1 week. By 1 month this had reduced to 42%.

134 patients were available for 1-year follow-up and primary healing of the fistula was seen in 99 people. 35 people had recurrence; 20 with serous discharge, 9 with pus discharge and 6 with bloody discharge.

The study presents results for the 416 people receiving VAAFT only. Only 134 of these were followed up at 1-year.

MRI was obtained for 150 patients with recurrent, multiple or high fistulae. This was used to assess the fistula anatomy.

Faecal continence was not formally evaluated.

Kochhar et al. 2014


Uncontrolled open-label study

Single centre


82 fistulae (70 simple and 12 complex) were treated with VAAFT.

The mean VAS score immediately following the procedure was 4 which was reduced to nil after 24 hours and no pain was reported at 1-week follow-up. All patients had returned to work 5 days after the procedure.

After 1 week, 28 patients (34.15%) had discharge from the wound. 13 patients (15.85%) had a recurrence during 6 month follow-up.

Anal manometry showed that there were no statistically significant changes in the mean resting anal pressures and mean anal squeeze pressures before and after the procedure. None of the patients reported any problems with faecal continence.

People with Crohn's disease and existing faecal incontinence were excluded from the study.

MRI scans were done for all participants.

Faecal continence was assessed using anal manometry in the preoperative period and again at 1 month and 6 months postoperatively.

The authors state that recurrence rates were lower than those observed in similar studies because the majority of fistulae treated in this study were simple rather than complex.

Meinero and Mori 2011


Uncontrolled open-label study

Single centre


136 complex fistulae were treated with VAAFT.

Primary healing was achieved in 72 people (73.5%) within 2 to 3 months. Of the 26 (26.5%) unsuccessful procedures, 19 people had a repeat VAAFT procedure, leading to another 9 fistulae being fully healed.

Recurrence rate was 26.5%.

No major complications, infection, incontinence or bleeding occurred as a result of treatment with VAAFT and all patients were discharged on the day of surgery. Mean VAS pain score in the first 48 hours following surgery was 4.5, no pain was reported after 1 week. All people had returned to work within 3 days.

All patients had complex fistulae which were defined as 'not treatable with fistulotomy'.

The authors of this study developed the VAAFT technique and so a high level of proficiency and possible bias should be considered when comparing primary healing rates to those observed in other studies.

Follow-up data for the entire cohort is only provided up to 3 months. The authors state that 62 people were followed up for at least 12 months and that in 54 (87.1%) of these primary healing had been achieved.

Anal continence was not formally evaluated.

This study was funded by the manufacturer.

Zarin et al. 2015


Uncontrolled open-label study



40 fistulae (16 simple and 24 complex) were treated with VAAFT.

Primary healing was achieved in 20 people at 6 weeks follow-up. Primary healing had been achieved in all 40 patients after 12 weeks of follow-up, however, 3 people had a repeat VAAFT procedure during this time.

No major complications were noted. 17 people (42.5%) had minor discharge and itching before healing.

This study is reported in a brief paper and some key information (such as inclusion/exclusion criteria) is missing.

40% of patients had simple, straight fistula tracts and 60% had complex fistulae. It is not explained how the fistula anatomy was assessed.

Recent and ongoing studies

  • identifier NCT02585167: Endoscopic treatment of complex anal fistulas. Status: recruiting (66 patients estimated). Estimated primary completion date: September 2017. Primary comparator: fistulotomy. Location: Denmark.

  • identifier NCT02313597: VAAFT Vs SETON in the management of high peri anal fistula. Status: recruiting (60 patients expected). Study completion date: July 2016. Location: Pakistan.