Anal fistula and pilonidal sinus disease coexisting simultaneously: An audit in a cohort of 1284 patients

Abstract

Fistula‐in‐ano and pilonidal disease are not known to occur together. In a retrospective study, all patients having fistula‐pilonidal disease coexisting simultaneously were included. Out of 1284 patients, 933 were operated (fistula‐in‐ano, 849; pilonidal disease, 77; and coexisting fistula‐pilonidal, 7). A total of 351 patients did not undergo any surgery (two patients had coexisting fistula‐pilonidal). Thus, a total of nine patients having coexisting fistula‐pilonidal sinus were included in the study (mean age 35.8 ± 19.9 years, M/F 7/2). pIn 6/9 patients, the pilonidal tract was communicating with fistula‐in‐ano, and in 3/9 patients, they were not communicating/connected. The connection could be established preoperatively with the help of MRI. In all patients with communicating fistula‐pilonidal sinus (n=6), the fistula was posterior. 6/9 patients had recurrent fistula and all (9/9) had multiple tracts. The fistula was high and complex in 8/9 patients (grade IV‐7, grade V‐1). 4/9 patients tested positive for tuberculosis while one patient was suffering from hidradenitis suppurativa. The latter improved on medical treatment. One patient did not agree for surgery and seven were operated. The disease healed in four patients, the disease did not heal in one patient, and two patients were in the convalescent stage. Anal fistula and pilonidal disease can coexist in a same patient and can even be connected. Such diseases are more complex and have a higher incidence of associated diseases like tuberculosis. Magnetic resonance imaging plays a pivotal role in diagnosis. If the connection is missed, the disease treatment becomes difficult.

1. INTRODUCTION

Anal fistula is a common disorder and has a prevalence of about 8.6 cases per 100 000 population.1 Its prevalence in men is around 12.3 cases per 100 000 population, and in women it is approximately 5.6 cases per 100 000 population.1 The pilonidal disease is common with a prevalence rate of about 26 per 100 000 population.2, 3 In spite of both the diseases being fairly common, yet there is still no data demonstrating the coexistence of both the diseases in a same patient. There have been reports showing pilonidal disease originating in the anal canal,4, 5, 6 but there was no demonstrable anal fistula in these cases.

The data of the last 7 years were scrutinised, and all cases having anal fistula coexisting with pilonidal disease were included in the study and analysed.

2. METHODS

All patients suffering from anal fistula and pilonidal disease who presented to a referral centre of anorectal disorders between the period September 2012 and February 2019 were screened. The approval for the study was taken from the Indus Hospital Ethics Committee.

2.1. Inclusion criteria

• Anal fistula and pilonidal disease coexisting in a patient at the same time irrespective of the fact whether they both were connected or not

2.2. Exclusion criteria

• Patient suffering from anal fistula and pilonidal disease at different times (not coexisting at the same time)

• Isolated anal fistula

• Isolated pilonidal disease

Magnetic resonance imaging (MRI) was performed in all the cases.7, 8 The fistula and pilonidal disease were termed “connected” when the pilonidal tract was seen communicating with the fistula tract in an MRI scan. The connection was confirmed on the operating table by injecting povidine‐iodine solution through the pilonidal sinus tract and noting its egress from the anus (Figure 1). Data of all the patients who had simultaneous anal fistula and pilonidal disease are provided in Table 1.

Figure 1.

Injecting povidine‐iodine solution through the pilonidal sinus tract and noting its egress from the anus demonstrating connection between the anal fistula and the pilonidal tract (patient on S. No. 1 in Table 1)

Table 1.

Fistula‐pilonidal coexisting simultaneously: patient details

S. No	Age/sex	Number of previous surgery	Fistula position	Fistulagrade	Number of fistula tracts	Horseshoe fistula	Fistula‐pilonidal connected	Associated diseases	Outcome
1 (Figures 1and 2)	33/M	0	Posterior	4	3	Yes	Yes	TB	Not healed
2	65/M	3	Posterior	4	4	No	Yes	TB	Not operated.Lost to follow‐up
3 (Figure 3)	32/M	5	Posterior	5	7	Yes	Yes	TB	Cured
4	32/M	1	Posterior	4	2	Yes	Yes	Nil	Inadequate follow‐up
5	67/M	1	Posterior	4	6	Yes	Yes	Nil	Cured
6 (Figure 4)	20/F	0	Posterior	4	2	No	Yes	HS	Not operated.Improved withmedicines
7	24/F	0	Anterior	4	11	No	No	TB	Cured
8	32/M	1	Anterior	2	2	No	No	Nil	Cured
9	18/M	2	Lateral 3 o'clock	4	2	No	No	Nil	Inadequatefollow‐up
Total	M = 7, F = 2 Mean = 35.8 years	Recurrent = 6/9	Posterior = 6/9	Grade 2 = 1/9Grade 4 = 7/9Grade 5 = 1/9	Range = 2‐11,Median = 3	Horseshoe = 4/9	Connected = 6/9	TB = 4, HS = 1	Not operated = 2,Inadequate follow‐up = 2,Cured = 4/5

Abbreviations: TB, tuberculosis; HS, hidradenitis suppurativa.

2.2.1. Management of pilonidal sinus

The closed procedures (primary closure or a flap procedure) to treat pilonidal disease were contraindicated in these patients as the pilonidal tract would get continuously contaminated because of the connected anal fistula. Therefore, the pilonidal disease was managed by an open procedure named LOCULA (Lay open with curettage under local anaesthesia).9, 10 LOCULA entailed laying open (deroofing) the pilonidal sinus, curetting the tracts, and then let the wound heal by secondary intention. The principle behind this procedure was that pilonidal disease was not malignant and should be treated like any ordinary abscess.11, 12 Therefore, wide local excision or even simple excision was an overtreatment, and hence unwarranted.11, 12 Another reason commonly advocated for doing flap procedures is do flatten the buttock contour so that recurrence could be avoided. However, simple steps taken in the postoperative period (regular hair removal and application of powder to keep natal cleft dry) work very well to prevent postoperative long‐term recurrences after LOCULA.9, 11, 12

2.2.2. Management of anal fistula

The anal fistula was managed depending on whether it was low fistula or high fistula. A low fistula (involving less than one‐third of the external sphincter) was managed by fistulotomy, and a high fistula (involving more than one‐third of the external sphincter) was managed by a sphincter‐saving procedure named TROPIS (transanal opening of intersphincteric space).13, 14 The latter is a sphincter‐saving procedure that has been shown to be effective in managing high fistulas. In this procedure, the intersphincteric tract is opened inside the rectum through the transanal route, and the tracts in the ischiorectal fossa are curetted, cleaned, and dilated.14, 15

Anal fistula was classified as per Garg's classification (Table 2). The standard Parks and St James University Hospital (SJUH) classifications were not used as these classifications had been found to be inaccurate because they neither correlated with the severity of the disease nor guided with regard to disease management.16, 17, 18, 19 On the other hand, the recently published Garg classification has been found to accurately classify fistula as per the severity of the disease and also guided with regard to its management.16, 17 Garg grades I and II could be safely managed by fistulotomy without any risk to incontinence, and fistulotomy was contraindicated in Garg grades III‐V.16, 17 In these high‐grade fistulas, sphincter‐sparing procedures should be performed.

Table 2.

Garg's classification for fistula‐in‐ano

Fistula	Grade	Description
Simple (fistulotomy safe)	I	Low fistula with a linear tract (intersphincteric or transsphincteric)
	II	Low fistula with multiple tracts or abscess or horseshoe tract (intersphincteric or transsphincteric)
Complex (fistulotomy contraindicated)	III	High transsphincteric fistula with a linear tract Fistula with associated comorbiditiesa
	IV	High transsphincteric fistula with multiple tracts or abscess or horseshoe tract
	V	High transsphincteric fistula with intersphincteric supralevator extension Suprasphincteric fistula or Extrasphincteric fistula

Note: Low fistula, <1/3 external sphincter involvement; high fistula, >1/3 sphincter involvement.

^aComorbidities with associated Crohn's, HIV, or AIDS disease; sphincter injury; postradiation exposure; or anterior fistula in a female.

3. RESULTS

A total of 1284 patients of anal fistula and pilonidal disease who were clinically and radiologically evaluated over the 7‐year period were screened. Out of 1284 patients, 933 were operated (849 for fistula‐in‐ano and 77 for pilonidal disease) and 351 patients did not agree for surgery. In the operated group, 7/933 patients had coexisting fistula‐pilonidal disease and in the non‐operated group, 2/351 had coexisting fistula‐pilonidal disease. Thus, a total of 9 patients had coexisting fistula‐pilonidal disease. Out of the two patients who were not operated, one did not agree for surgery and the other was suffering from hidradenitis suppurativa, which was managed with medical treatment (retinoic acid and antibiotics) (Table 1). The mean age was 35.8 ± 19.9 years and seven were males (Table 1). In 6/9 patients, the pilonidal tract was communicating with the anal fistula (Table 1, Figure 2, 3, 4), and in the remainder three patients, the coexisting pilonidal disease and anal fistula were not connected with each other. In all the communicating fistulas (6/6), the fistula position was posterior (Table 1, Figure 2, 3, 4). The fistula was horseshoe in 4/6 of these fistulas (Table 1, Figure 2). In non‐communicating fistulas (n = 3), the fistula position was anterior in two and lateral in one patient. 6/9 patients had recurrent fistula and all (9/9) patients had multiple tracts [the number of tracts ranged from 2 to 11 (median 3)] (Table 1). The fistula was high and complex in 8/9 patients (grade II‐one, grade IV‐seven, and grade V‐one). 4/9 patients tested positive for tuberculosis while one patient was suffering from hidradenitis suppurativa (Figure 4). The latter improved on medical treatment and the remaining eight patients were advised surgery. One patient did not agree for surgery and seven underwent operation. The fistula was low in one patient and fistulotomy was done in this patient. In the remaining operated fistulas (6/7), the fistula was high and was managed by the TROPIS procedure.13, 14 The pilonidal sinus disease was managed by LOCULA in all the seven patients.9, 10 The two patients were in the convalescent stage (inadequate follow‐up). In the remaining five patients with adequate follow‐up, the disease healed completely (both anal fistula and pilonidal disease) in four patients (4/5) and the disease did not heal in one (1/5) patient.

Figure 2.

The anal fistula‐pilonidal connection seen (patient on S. No. 1 in Table 1). Left upper, sagittal view—schematic diagram; right upper, sagittal view—MRI scan; left lower, axial view—schematic diagram; right lower: axial view—MRI scan

Figure 3.

The fistula‐pilonidal connection and intersphincteric horseshoe fistula tract (patient on S. No. 3 in Table 1). Left upper, sagittal view—schematic diagram; right upper, sagittal view—MRI scan; left lower, axial view—schematic diagram; right lower, axial view—MRI scan

Figure 4.

The MRI scans of fistula‐pilonidal connection seen in a patient of hidradenitis suppurativa (patient on S. No. 6 in Table 1). Left upper, sagittal view—before treatment; right upper, sagittal view—after medical treatment; left lower, axial view—before treatment; right lower, axial view—after medical treatment. The coccygeal inflammation and oedema seen in left sided images (pre‐treatment) has resolved in right sided images (post‐treatment)

4. DISCUSSION

The present study demonstrated that anal fistula and pilonidal disease could not only coexist but also communicate with each other. The latter happened in two‐thirds (6/9) of the patients. The anal fistula was anterior or lateral in position in all non‐communicating (3/9) and posterior in all communicating fistula‐pilonidal patients (6/9) (Figure 2, 3, 4).

Although there are reports of pilonidal disease occurring in the anal canal,4, 5, 6 there was hardly any case in the literature in which sacrococcygeal pilonidal sinus spread to and got communicated with fistula‐in‐ano. Apart from the large cohort, the other reason for identifying such cases in the present study could be the mandatory usage of MRI imaging in every patient of the cohort. Had MRI not been performed in every patient, then it is possible that the connection in these cases (communicating fistula‐pilonidal disease) could have been missed in the present study as well. The routine availability and low price of an MRI scan (US $100‐$110) in India made it feasible to obtain an MRI scan in every patient suffering from fistula‐in‐ano.7

The pathophysiology of the connection in cases of the communicating fistula‐pilonidal disease could be threefold: (a) both the diseases could be independently coexisting and communicated accidentally, (b) the pilonidal disease was primary and its tract deepened and opened in the anorectum to form the fistula, and (c) the anal fistula was primary and one of its tract progressed in the posterior direction to open in the lower back. It was difficult to confirm as which of these three possibilities was responsible for the communicating fistula‐pilonidal cases. However, the third possibility looked more likely as anal fistula was a more virulent disease and had tendency to spread more when compared with the pilonidal sinus. It is also possible that some of these cases might just be the extension of anal fistula up to the lower back (usual site of pilonidal sinus), with no actual pilonidal disease being present. Once the fistula‐in‐ano had made external opening in the middle of natal cleft in the lower back, then few hairs might have accidently slipped in or got sucked in the fistula tract giving the impression of a coexisting pilonidal sinus.

Irrespective of the pathophysiology, the present study highlighted a very important point that in recurrent pilonidal disease with deep tracts, the possibility of coexisting fistula‐in‐ano should be ruled out. In few cases, the opening of the pilonidal sinus might be the only opening present in communicating pilonidal‐fistula patients (Figure 3). In such cases, the fistula‐in‐ano might be completely missed, and the patient might keep on suffering from repeated recurrences after surgery of the pilonidal disease. Therefore, MRI or transrectal ultrasound would be extremely helpful in diagnosing the associated fistula‐in‐ano.7, 8

The prevalence of associated secondary infection (4/6) was quite high in the study cohort especially in communicating fistula‐pilonidal patients (n=6). 3/6 of these patients were suffering from tuberculosis and 1/6 patients was suffering from hidradenitis suppurativa. Moreover, 6/9 patients had recurrent fistula. The diagnosis of tuberculosis is often missed due to which tuberculosis has higher association with recurrent fistula.20 The latter is one of the prominent reasons for the tuberculosis fistula being more complex and extensive. Therefore, the possibility of tuberculosis‐infected fistula‐in‐ano had a higher possibility of spreading posteriorly leading to and reaching the lower back. The possibility of tuberculosis is also higher in recurrent pilonidal sinus with deeper tracts.21

The treatment of communicating fistula‐pilonidal presented a therapeutic challenge. The fistula in majority (8/9) of these cases was high fistula (involving more than one‐third of external sphincter) and was thus not suitable for fistulotomy. A sphincter‐saving procedure, TROPIS (transanal opening of intersphincteric space) was done in all these cases.13, 14 The treatment of pilonidal disease in communicating fistula‐pilonidal was also quite challenging. As a result of communication of pilonidal sinus with the rectum, any closed (primary closure or flap) procedure was contraindicated in these patients. Therefore, an open procedure with minimal morbidity (LOCULA)9, 10 was performed along with the sphincter‐saving procedure for fistula. The combination of these procedures proved effective as the fistula‐pilonidal disease got healed in 80% (4/5) patients. In the patient with associated hidradenitis suppurativa, the medical management (retinoic acid and rifampicin) was initiated. The patient responded quite well to the medical management and the disease resolved satisfactorily (Figure 4).

In conclusion, anal fistula and pilonidal sinus can not only coexist in the same patient but can also communicate with each other. MRI plays a pivotal role in diagnosing such patients. The fistula in communicating fistula‐pilonidal disease is usually high and complex, therefore such patients present a therapeutic challenge. There is high association with secondary diseases like tuberculosis in these patients. In some patients with communicating fistula‐pilonidal sinus, pilonidal opening may be the only opening present with no fistula opening in the perianal region. Therefore, in patients with recurrent pilonidal disease refractory to treatment, MRI should be used to rule out an associated anal fistula disease.

CONFLICT OF INTEREST

The authors declare no potential conflict of interest.

AUTHOR CONTRIBUTIONS

P.G. conceived and designed the study, contributed to the acquisition of data, analysis of data, drafting, revising, final approval of the draft, and submission of the manuscript; and is the guarantor of the review.

Garg P. Anal fistula and pilonidal sinus disease coexisting simultaneously: An audit in a cohort of 1284 patients. Int Wound J. 2019;16:1199–1205. 10.1111/iwj.13187