Abstract
Background
Promotion of healing of the anal wound after fistulotomy may help accelerate recovery and return to work. The present study aimed to assess the effect of marsupialisation of the edges of the laid open fistula track on wound healing after anal fistulotomy for simple anal fistula.
Methods
This was a prospective randomised trial on patients with simple anal fistula. Patients were randomly assigned to one of two groups; group I underwent anal fistulotomy and group II underwent anal fistulotomy and marsupialisation of the edges of the laid open track. Outcomes of the study were time to achieve complete wound healing, operation time, postoperative pain and complications.
Results
Sixty patients of mean age of 40.8 years with simple anal fistula were randomly divided into two equal groups. No significant differences between the two groups regarding operation time (16.8 vs 18.4 minutes; P = 0.054), postoperative pain score (1.6 vs 1.2; P = 0.22), and complication rates were recorded. Group II achieved complete healing in a significantly shorter duration than group I (5.1 vs 6.7 weeks; P < 0.0001).
Conclusion
Marsupialisation of the edges of the laid open fistula track after fistulotomy resulted in quicker wound healing with similar complication and recurrence rates to lay open fistulotomy alone.
Keywords: Fistula, Fistulotomy, Marsupialisation, Healing, Randomised trial
Introduction
Anal fistula is one of the most common anorectal conditions encountered by general and colorectal surgeons with an estimated prevalence of 8.6 cases per 100,000 population.1 The majority of anal fistulas arise from cryptoglandular infection whereas a small percentage of cases are secondary to specific pathology such as Crohn’s disease, sexually transmitted diseases, or malignancy.2
Parks and colleagues have classified anal fistula into four main types with numerous variations of each.3 In general, anal fistula can be divided into simple and complex fistulas. While simple anal fistulas can be adequately treated with lay open fistulotomy, this approach cannot be followed with complex fistulas, as they involve a considerable portion of anal sphincter fibres, so to lay open of the entire track of complex fistulas may entail a higher risk of faecal incontinence.4
Fistulotomy has proved to be the optimal treatment of simple anal fistula and has been strongly recommended by the practice guideline of the American Society of Colon and Rectal Surgeons.5 When applied in the proper indications, fistulotomy is associated with a low incidence of recurrence of anal fistula and complete healing of the anal wound is usually achieved between four and six weeks according to a recent meta-analysis.6
Attempts to accelerate wound healing and improve the outcome of fistulotomy have been made by some investigators. Alvandipour et al examined the efficacy of sucralfate ointment in a randomised placebo-controlled trial and concluded that topical sucralfate managed to reduce postoperative pain and improve wound healing in patients undergoing anal fistulotomy.7
Another technique that may hasten wound healing after anal fistulotomy is marsupialisation of the wound edges, which was described to be associated with less postoperative bleeding, less need for analgesia and faster wound healing.8–10 The accelerated wound healing after marsupialisation of the edges of the laid open fistula track was attributed to a smaller wound size, with to non-marsupialised tracks.10
The present study aimed to assess the effect of marsupialisation of the edges of the laid open track after fistulotomy compared with standard fistulotomy in simple anal fistula with regard time to complete wound healing, postoperative pain and complications. We hypothesised that marsupialisation of the wound edges would accelerate wound healing without causing more pain or complications than fistulotomy alone.
Materials and methods
Study design and setting
This was a prospective randomised single-blinded clinical study on patients with simple, low anal fistula who were surgically treated in the general surgery department and colorectal surgery unit of Mansoura University Hospitals in the period of February 2017 to January 2018. The protocol of the study was approved by the institutional review board. The trial has been registered in the clinical trials registry (www.clinicaltrials.gov) with special identified NCT03595839.
Eligibility criteria
Adult patients of both sexes presented with primary simple anal fistula were recruited. Simple anal fistula was defined as intersphincteric and low trans-sphincteric fistulas involving less than one-third of the external anal sphincter fibres. We excluded patients with complex or recurrent anal fistulas. Complex anal fistula was defined as high trans-sphincteric, extra-sphincteric, supra-sphincteric anal fistulas. Patients with secondary anal fistula caused by specific pathology as inflammatory bowel diseases, tuberculosis, sexually transmitted diseases, or malignancy were excluded. Patients with symptoms of faecal incontinence, patients with history of previous anal surgery, diabetic patients and patients on long course of steroids or immunosuppressive drugs were also excluded.
Preoperative assessment
Detailed history was taken from the patients with regard the complaint and its duration, associated medical conditions, previous anal surgery, previous treatments of the current condition, presence of anal pain, and continence state as assessed by Wexner continence score.11
Local anorectal examination was performed with the patients lying in the left lateral position. Direct inspection of the anus and perineum was done to detect the site and number of external opening(s), exclude presence of skin tag or prolapsed haemorrhoids. Digital rectal examination was performed to assess the condition of anal sphincter muscles and exclude coexisting anorectal pathology such as anal polyp, stricture, mass or ulcers. An anoscope was inserted in the anal canal to exclude associated rectal lesions. Objective preoperative assessment of all patients was performed with MRI to exclude patients with complex anal fistula.
Random sequence generation, allocation concealment and blinding
After admission to the surgical ward and before undergoing surgical treatment, patients were randomly assigned to one of two equal groups; group I underwent fistulotomy and group II underwent fistulotomy and marsupialisation of the wound edges. Simple randomisation was achieved through an online randomisation software (www.randomization.com). Allocation concealment was undertaken by sealed envelope method as randomly generated treatment allocations were placed within sealed opaque envelopes. After obtaining patient’s consent to participate in the trial, an envelope was opened and the patient was assigned to the allocated treatment group.
The trial was single blinded as patients were aware of the nature of the study, but not of the type of procedure they underwent while the operating surgeons were aware of the nature of the study.
Surgical technique
Written informed consents to participate in the study were obtained from all patients prior to enrolment. The surgical procedures were performed under spinal anaesthesia with patients being placed in the modified lithotomy position.
Group I: Examination under anaesthesia was performed and the internal opening of the fistula track was localised by injection of povidone iodine through the external opening. Afterwards, a malleable metallic probe was inserted through the external opening till it came out through the internal opening. The entire fistula track was laid open (Fig 1), preserving the fibres of the external anal sphincter in intersphincteric fistulas and dividing less than 30% of the external sphincter fibres in low trans-sphincteric fistulas. The laid open track was curetted carefully by a surgical curette.
Figure 1.
Laying open of the fistula track using electrocautery.
Group II: The same steps as group I were followed then marsupialisation of the laid open fistula track was undertaken from the distal to the proximal end by suturing the wound edges with the edge of fistula tract (Figures 2 and 3) using interrupted 3-0 polyglactin sutures as demonstrated by previous investigators.9
Figure 2.
Marsupialisation of the edges of the laid-open fistula track.
Figure 3.
Final view after completion of marsupialisation of the laid-open fistula track.
Postoperative care
Patients were instructed to start clear oral fluids within four hours of surgery. The procedures were performed as daycase surgery for all patients. Intravenous analgesics (diclofenac potassium, 50 mg) were administered on demand. Patients were discharged home with instructions to use a sitz bath twice per day and after each bowel motion and to take laxatives for five days to avoid constipation in the early postoperative period.
Outcomes of the study
The primary outcome of the trial was the duration to achieve complete wound healing after each procedure as assessed by clinical examination. Complete wound healing was defined as complete epithelialisation of the wound with no evidence of external fistula opening or perianal discharge. No measurement of the size or the depth of the anal wound was performed during follow-up. Secondary outcomes included postoperative pain, recurrence of anal fistula, operation time calculated from the injection of povidone iodine through the external opening to the dressing of the postoperative wound, complications including faecal incontinence and affects on lifestyle after treatment. Recurrence of anal fistula was defined as the clinical occurrence of the fistula after recovery of the surgical wound, occurring within one year after the original procedure.
Follow-up
Patients were aware of being included in a clinical trial that requires close follow-up in the first six months after surgery and were instructed to visit the outpatient clinic every week for three months, then every month for six months postoperatively. Patients who did not attend the scheduled appointment were contacted by telephone and were asked to visit the clinic to ensure good healing of their anal wound and exclude persistent or recurrent anal fistulas.
Assessment of the outcome of each procedure was done by a consultant of colorectal surgery, who clinically assessed healing of the anal wound and recorded whether the wound has completely healed or not in the patients’ files at every visit. Although the sutures of marsupialisation could have been easily detectable during follow-up, the outcome assessors were unaware of the nature of the trial, to minimize the risk of bias.
Wound healing was assessed at every visit and recorded. Recurrence of anal fistula and complications as rectal bleeding, wound infection or faecal incontinence were recorded. The continence state was evaluated using Wexner incontinence score at every visit. Anal pain at one week after surgery was assessed by visual analogue scale ranging from 0 to 10 where 0 indicated no pain and 10 implied the worst possible pain. At one month of follow-up, the patients were offered a simple questionnaire about the affects on their lifestyle (physical, social, and sexual activities) after treatment in each group.10
Sample size calculation and statistical analysis
According to previous trials that compared fistulotomy and fistulotomy with marsupialisation in terms of wound healing, the mean healing time ranged between 6 and 10 weeks after fistulotomy and between 4.8 and 6 weeks after fistulotomy with marsupialisation.8–10 We assumed that performing marsupialisation with fistulotomy would accelerate the healing of the anal wound to be completely achieved within 4.5 weeks compared with 6 weeks after fistulotomy alone.
Using sample size calculation software (www.clinicalc.com) a minimum sample of 46 patients, equally divided into two groups, was needed to achieve a study power of 80% with alpha set at 5%. Estimating a dropout rate and loss to follow-up of 20%, a total of 60 patients were ultimately included. Data were analysed by SPSS Version 21. Continuous data were expressed as mean plus or minus standard deviation (SD) or median and range. Categorical variables were expressed as number and percent. Student t-test was used to process continuous data and Fisher exact test or chi square test was used for analysis of categorical variables. P-values less than 0.05 were considered significant.
Results
Patients’ characteristics
After initial evaluation of 73 patients with anal fistula, nine were excluded (seven had complex anal fistula in MRI and two had history of haemorrhoidectomy) and two declined to participate in the study; thus, 62 patients with simple anal fistula were included in the trial and were randomised to two equal groups; group I was treated with anal fistulotomy and group II was treated with anal fistulotomy and marsupialisation. Two patients were lost to follow-up, so 60 patients with simple anal fistula were ultimately included. The process of patients’ recruitment is illustrated in the CONSORT flow chart (Fig 4).
Figure 4.
Consort flow chart demonstrating patients’ recruitment and selection.
There were 50 men (83.3%) and 10 women (16.7%) with a mean age of 40.8 ± 12.5 years (range 18–72 years). Fifty-five patients (91.6%) complained of perianal discharge, 30 (50%) of pruritus and 17 (28.3%) of anal pain. The mean duration of symptoms was 4.1 ± 2.6 months.
According to magnetic resonance imaging, 42 patients had intersphincteric anal fistula (grade I) and 18 had low trans-sphincteric anal fistula (grade III). There were no statistically significant differences between the two groups regarding patients’ characteristics, clinical presentation and type of anal fistula (Table 1).
Table 1.
Characteristics of the patients in both groups.
| Variable | Group 1: Fistulotomy (n = 30) | Group 2: Fistulotomy with marsupialisation (n = 30) | P-value |
| Mean age (years) | 38.3 ± 12.1 | 43.5 ± 12.5 | 0.1 |
| Ratio male : female | 24 : 6 | 26/4 | 0.73 |
| Perianal discharge (%) | 26 (86.6) | 29 (96.6) | 0.35 |
| Pruritus (%) | 14 (46.6) | 16 (53.3) | 0.79 |
| Anal pain (%) | 9 (30) | 8 (26.6) | 0.77 |
| Mean duration of symptoms (months) | 4.7 ± 3 | 5.8 ± 4.9 | 0.29 |
| Type of anal fistula, n (%): | 0.78 | ||
| Intersphincteric | 22 (73.3%) | 20 (66.6%) | |
| Low trans-sphincteric | 8 (26.6%) | 10 (33.3%) |
Operation time and postoperative pain
The mean operation time for both groups was comparable (16.8 ± 3.1 minutes for fistulotomy vs 18.4 ± 3.2 minutes for fistulotomy and marsupialisation; P = 0.054). All procedures were performed as daycase surgery. Postoperative pain scores at one week after surgery were comparable in both groups (1.6 ± 1.4 in group I vs 1.2 ± 1.1 in group II; P = 0.22; Table 2).
Table 2.
Outcomes of fistulotomy versus fistulotomy and marsupialisation.
| Variable | Group 1: Fistulotomy (n = 30) | Group 2: Fistulotomy with marsupialisation (n = 30) | P-value |
| Mean operation time (minutes) | 16.8 ± 3.1 | 18.4 ± 3.2 | 0.054 |
| Mean pain score at one week | 1.6 ± 1.4 | 1.2 ± 1.1 | 0.22 |
| Complications (%): | |||
| Faecal incontinence | 1 (3.3) | 0 | 1 |
| Bleeding | 2 (6.6) | 0 | 0.29 |
| Urinary retention | 1 (3.3) | 2 (6.6) | 1 |
| Total | 4 (13.3) | 2 (6.6) | 0.67 |
| Mean time to complete healing (weeks) | 6.7 ± 1.7 | 5.1 ± 1 | < 0.0001 |
| Duration of healing process (%): | 0.039 | ||
| Up to 4 weeks | 4 (13.3) | 12 (40) | |
| More than 4 weeks | 26 (86.7) | 18 (60) | |
| Recurrence (%) | 1 (3.3) | 0 | 1 |
| Mean duration of follow-up (months) | 11.25± 1.1 | 11.5± 1.7 | 0.5 |
Complications
One patient developed minor faecal incontinence (Wexner score = 3) in group I while none of group II patients experienced continence disturbances. The patient who developed minor faecal incontinence showed spontaneous improvement in the continence state at four months postoperatively. Bleeding from the anal wound occurred in two patients of group I and was treated conservatively, while none of group II patients experienced bleeding. Urinary retention was recorded in one patient of group I and two patients of group II and was relieved with urethral catheterisation (Table 2).
Healing and recurrence
The mean duration to complete healing of anal wound was 6.7 ± 1.7 weeks in group I and 5.1 ± 1 weeks in group II (P < 0.0001). Healing was completed by four weeks in four patients in group I and 12 in group II. Complete healing took longer than four weeks in 26 patients in group I and 18 patients in group II (P = 0.039). Recurrence of anal fistula was recorded in one patient in group I, whereas no recurrence was recorded in group II (Table 2).
The mean duration of follow-up in both groups was comparable, with no statistically significant difference (11.25 ± 1.1 vs 11.5 ± 1.7; P = 0.5). The lifestyle of both groups were similarly affected after treatment in terms of physical, social and sexual activity, with no statistically significant differences observed (Table 3).
Table 3.
Adverse effects on lifestyle after treatment in each group.
| Group | Physical | Social | Sexual | |||||||||
| Not at all | To some extent | Greatly | P-value | Not at all | To some extent | Greatly | P-value | Not at all | To some extent | Greatly | P-value | |
| 1 (n = 30)a | 22 | 7 | 1 | 0.76 | 24 | 4 | 2 | 0.38 | 27 | 3 | 0 | 0.61 |
| 2 (n = 30)b | 24 | 6 | 0 | 4 | 1 | 1 | 29 | 1 | 0 | |||
aFistulotomy (n = 30)
bFistulotomy with marsupialisation (n = 30)
Discussion
Treatment of anal fistula remains challenging despite technical advancement and the introduction of new surgical techniques.12–14 The triad of healing, recurrence and continence are the major forces which change the adoption of each technique. While simple anal fistula is optimally treated with lay open of the fistula track as devised by recent guidelines,5 treatment of complex fistulas is more challenging, as the ideal treatment should balance the need to eradicate the fistula track and its extensions with the necessity to preserve the anal sphincters.
The duration required to achieve complete healing of the anal wound is an important determinant of superiority among the different techniques used for treatment of anal fistula. Quicker wound healing is associated with reduced days of daily dressing and wound care which would, subsequently, reduce the inconvenience and costs associated with wound care. Attempts to promote wound healing after anal fistula surgery have been described in the literature. Gupta and colleagues conducted a randomised controlled trial and reported that topical sucralfate is a safe and effective method for promoting mucosal healing and providing analgesia after anal fistulotomy.15 In another randomised trial, Chen et al demonstrated that silicate-based wound dressing effectively reduced wound size and hastened healing after anorectal surgery.16 Marsupialisation of the wound edges after standard fistulotomy has been investigated in previous randomised trials and has been reported to accelerate wound healing without significant affecting continence status or recurrence rate.8–10
The present study included 60 patients with simple anal fistula who underwent either fistulotomy alone or fistulotomy with marsupialisation. The two groups were comparable regarding patient demographics, clinical presentation and type of fistula, which highlights the absence of selection bias owing to the appropriate randomisation of patients to the two groups. The majority of patients were men of middle age, in concordance with the male predominance of anal fistula that we highlighted in a previous publication.17
The group in which marsupialisation of the wound edges was undertaken achieved complete healing significantly earlier than the fistulotomy only group. This significant reduction in time required for complete wound healing could be explained by a reduction in the size of the anal wound after fistulotomy when complemented by marsupialisation. Although we did not measure the size of anal wound in each group, Pescatori et al implied that marsupialisation significantly halved the wound size at the end of the operation from a mean of 1749 mm2 in fistulotomy only group to 819 mm2 in the marsupialisation group.9
Previous trials have also demonstrated better outcomes of combining marsupialisation with anal fistulotomy.8–10,18 However, these trials entailed different methodologies and patient population to our trial. One study included patients with high, complex and recurrent anal fistula,9 whereas our trial included patients with simple anal fistula only. Another study performed either fistulotomy or fistulectomy in addition to marsupialisation,10 which may be confounding, since fistulectomy results in a larger and deeper wound that takes longer duration to heal, compared to fistulotomy. Two trials used continuous absorbable sutures to perform marsupialisation,9,18 whereas we used interrupted absorbable sutures.
Marsupialisation of the wound edges proved to be an easy replicable technique that achieved earlier wound healing, yet without increasing the operation time significantly. The mean operation time was comparable between the two groups in our study, in line with previous studies.8–10 In addition, the two groups were comparable with regard to postoperative pain, in agreement with other studies,9,10,18 which have also reported no significant impact of marsupialisation on postoperative anal pain at different time points. However, one trial recorded the need to remove the marsupialisation suture in one patient because of persistent anal pain.9
Both groups had similar postoperative complication rate in terms of continence disturbance, bleeding and urine retention. Although it did not reach a significant level, none of the patients in the marsupialisation group experienced postoperative bleeding compared with two patients in the fistulotomy only group. Pescatori et al testified a significantly lower postoperative bleeding in the marsupialisation group.9 The rationale for the lower incidence of bleeding may be attributed to decreased wound size by marsupialisation or to the direct haemostatic effect of the sutures used in marsupialisation.
Anal continence is a major concern after anal fistula surgery. As formerly highlighted, there was no significant difference regarding continence disturbance between the two groups. None of the patients in the marsupialisation group experienced faecal incontinence, while one patient in the fistulotomy only group experienced minor, transient disturbance in the continence state. Ho et al showed a significant drop in the maximum anal squeeze pressure in the fistulotomy only group at three months postoperatively compared with the marsupialisation group.8 The authors concluded that marsupialisation induced less deformity and scarring of the external anal sphincter.
Only one patient in the present study experienced recurrence of anal fistula on follow-up and required placement of draining seton. The two groups were comparable with regard the incidence of recurrence. Although recurrence of anal fistula after laid-open fistulotomy was performed for simple, low anal fistula is not typically expected, certain factors such as presence of secondary tracks or supralevator extension may result in a higher incidence of recurrence if they were missed during the primary surgery.19,20
Although the consensus statement of the Italian Society of Colorectal Surgery recommended marsupialisation of the anal wound after fistulotomy in line with our findings, it is worthy to note that this recommendation was based only on two randomised trials which entailed heterogeneous patient populations and methodologies.21 Further randomised trials may help to substantiate the evidence for the efficacy of marsupialisation technique.
In summary, patients who underwent marsupialisation in addition to anal fistulotomy achieved complete wound healing and no longer required daily sitz baths and wound care approximately 10 days earlier than patients who underwent fistulotomy only, which may have a positive impact on the overall recovery, return to daily activities and patient convenience. Marsupialisation required a longer operative time, but of only two to three minutes. Comparable pain scores indicate that the sutures taken for marsupialisation were not associated with more severe pain than the conventional fistulotomy.
The present trial is not without limitations, including being a single-institution study comprising a relatively small number of patients in each group, which did not allow secondary subgroup analyses. The average follow-up duration was approximately 12 months; longer follow-up is needed to ascertain the long-term outcome of marsupialisation. Furthermore, we did not measure the size of the anal wound upon completion of the procedure in each group and serially during follow-up, which may have added more information about the rate by which marsupialisation hastened healing of the anal wound. Further, larger multicentre trials on the efficacy of marsupialisation of the wound edges after fistulotomy are needed to confirm the findings of the present trial.
Conclusion
Marsupialisation of the edges of the laid-open fistula track after fistulotomy resulted in quicker healing with similar complication and recurrence rates to lay open fistulotomy alone.
References
- 1.Sainio P. Fistula-in-ano in a defined population. Incidence and epidemiological aspects. Ann Chir Gynaecol 1984; (4): 219–224. [PubMed] [Google Scholar]
- 2.Poggio J. Fistula-in-ano. Medscape 2018, 11 June https://emedicine.medscape.com/article/190234-overview#a2 (cited April 2019).
- 3.Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg 1976; (1): 1–12. [DOI] [PubMed] [Google Scholar]
- 4.Bubbers EJ, Cologne KG. Management of complex anal fistulas. Clin Colon Rectal Surg 2016; (1): 43–49. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Vogel JD, Johnson EK, Morris AM et al. Clinical practice guideline for the management of anorectal abscess, fistula-in-ano, and rectovaginal fistula. Dis Colon Rectum 2016; (12): 1,117–1,133. [DOI] [PubMed] [Google Scholar]
- 6.Xu Y, Liang S, Tang W. Meta-analysis of randomized clinical trials comparing fistulectomy versus fistulotomy for low anal fistula. SpringerPlus 2016; (1): 1,722. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Alvandipour M, Ala S, Tavakoli H et al. Efficacy of 10% sucralfate ointment after anal fistulotomy: a prospective, double-blind, randomized, placebo-controlled trial. Int J Surg 2016; (Pt A): 13–17. [DOI] [PubMed] [Google Scholar]
- 8.Ho YH, Tan M, Leong AF, Seow-Choen F. Marsupialization of fistulotomy wounds improves healing: a randomized controlled trial. Br J Surg 1998; : 105–107. [DOI] [PubMed] [Google Scholar]
- 9.Pescatori M, Ayabaca SM, Cafaro D et al. Marsupialization of fistulotomy and fistulectomy wounds improves healing and decreases bleeding: a randomized controlled trial. Colorectal Dis 2006; : 11–14. [DOI] [PubMed] [Google Scholar]
- 10.Jain BK, Vaibhaw K, Garg PK et al. Comparison of a fistulectomy and a fistulotomy with marsupialization in the management of a simple anal fistula: a randomized, controlled pilot trial. J Korean Soc Coloproctol 2012; : 78–82. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Jorge J, Wexner S. Etiology and management of fecal incontinence. Dis Colon Rectum 1993; (1): 77–97. [DOI] [PubMed] [Google Scholar]
- 12.Emile SH, Elfeki H, Shalaby M, Sakr A. A Systematic review and meta-analysis of the efficacy and safety of video-assisted anal fistula treatment (VAAFT). Surg Endosc 2018; (4): 2,084–2,093. [DOI] [PubMed] [Google Scholar]
- 13.Hong KD, Kang S, Kalaskar S, Wexner SD. Ligation of intersphincteric fistula tract (LIFT) to treat anal fistula: systematic review and meta-analysis. Tech Coloproctol 2014; (8): 685–691. [DOI] [PubMed] [Google Scholar]
- 14.Narang SK, Keogh K, Alam NN et al. A systematic review of new treatments for cryptoglandular fistula in ano. Surgeon 2017; (1): 30–39. [DOI] [PubMed] [Google Scholar]
- 15.Gupta PJ, Heda PS, Shrirao SA, Kalaskar SS. Topical sucralfate treatment of anal fistulotomy wounds: a randomized placebo-controlled trial. Dis Colon Rectum 2011; (6): 699–704. [DOI] [PubMed] [Google Scholar]
- 16.Chen S, Huan Z, Zhang L, Chang J. The clinical application of a silicate-based wound dressing (DermFactor®) for wound healing after anal surgery: a randomized study. Int J Surg 2018; : 229–232. [DOI] [PubMed] [Google Scholar]
- 17.Emile SH, Elgendy H, Sakr A et al. Gender-based analysis of the characteristics and outcomes of surgery for anal fistula: analysis of more than 560 cases. J Coloproctol (Rio J) 2018; (3): 199–206. [Google Scholar]
- 18.Sahakitrungruang C, Pattana-Arun J, Khomvilai S et al. Marsupialization for simple fistula in ano: a randomized controlled trial. J Med Assoc Thai 2011; (6): 699–703. [PubMed] [Google Scholar]
- 19.Emile SH, Elfeki H, Thabet W et al. Predictive factors for recurrence of high transsphincteric anal fistula after placement of seton. J Surg Res 2017; : 261–268. [DOI] [PubMed] [Google Scholar]
- 20.Visscher AP, Schuur D, Slooff RA et al. Predictive factors for recurrence of cryptoglandular fistulae characterized by preoperative three-dimensional endoanal ultrasound. Colorectal Dis 2016; (5): 503–509. [DOI] [PubMed] [Google Scholar]
- 21.Amato A, Bottini C, De Nardi P et al. Evaluation and management of perianal abscess and anal fistula: a consensus statement developed by the Italian Society of Colorectal Surgery (SICCR). Tech Coloproctol 2015; (10): 595–606. [DOI] [PubMed] [Google Scholar]