Puborectalis Muscle Involvement on Magnetic Resonance Imaging in Complex Fistula: A New Perspective on Diagnosis and Treatment

Efficacy and safety of transanal opening of intersphincteric space in the treatment of high complex anal fistula: A meta‑analysis

The best treatment of high complex anal fistula (HCAF) is to avoid anal incontinence while improving the cure rate. On this basis, several surgical procedures for preserving the anal sphincter have been proposed. The purpose of the present study was to evaluate the efficacy and safety of transanal opening of intersphincteric space for treating HCAF. PubMed, Cochrane Library, China National Knowledge Infrastructure and the Wanfang databases were searched to collate all the articles on transanal opening of intersphincteric space for treating HCAF. A total of two researchers independently completed the whole process, from screening and inclusion to data extraction and the data was included in the RevMan 5.3 software for analysis. The main outcomes included the patients' essential characteristics, primary healing rate, management after recurrence, final healing rate, anal incontinence score before and after surgery, postoperative complication rate and types of complications. A total of six articles were included in this meta-analysis. The results showed that the weighted final healing rate of patients following transanal opening of intersphincteric space was 89% [risk differences (RD)=0.89; 95% confidence interval (CI)=0.86-0.92; I2=0%; P<0.00001]. The results of the anal incontinence score showed that there was no significant difference between the results before and after transanal opening of intersphincteric space surgery mean differences [(MD)=-0.04, Cl=-0.10-0.02, I2=0%; P=0.21]. Only 11 patients were reported to have complications, including urinary retention and bleeding following transanal opening of intersphincteric space with a complication rate of 8% (11/138) and the weighted average complication rate was 6% (RD=0.06,95% CI=0.02-0.10; I2=9%; P=0.003). Transanal opening of intersphincteric space has a high cure rate, a favorable anal incontinence score, fewer types of postoperative complications and a low complication rate; it can be used as a minimally invasive and sphincter-preserving surgical method for treating HCAF and is worthy of further promotion and research in clinical practice.

Guidelines to diagnose and treat peri-levator high-5 anal fistulas: Supralevator, suprasphincteric, extrasphincteric, high outersphincteric, and high intrarectal fistulas

Supralevator, suprasphincteric, extrasphincteric, and high intrarectal fistulas (high fistulas in muscle layers of the rectal wall) are well-known high anal fistulas which are considered the most complex and extremely challenging fistulas to manage. Magnetic resonance imaging has brought more clarity to the pathophysiology of these fistulas. Along with these fistulas, a new type of complex fistula in high outersphincteric space, a fistula at the roof of ischiorectal fossa inside the levator ani muscle (RIFIL), has been described. The diagnosis, management, and prognosis of RIFIL fistulas is reported to be even worse than supralevator and suprasphincteric fistulas. There is a lot of confusion regarding the anatomy, diagnosis, and management of these five types of fistulas. The main reason for this is the paucity of literature about these fistulas. The common feature of all these fistulas is their complete involvement of the external anal sphincter. Therefore, fistulotomy, the simplest and most commonly performed procedure, is practically ruled out in these fistulas and a sphincter-saving procedure needs to be performed. Recent advances have provided new insights into the anatomy, radiological modalities, diagnosis, and management of these five types of high fistulas. These have been discussed and guidelines formulated for the diagnosis and treatment of these fistulas for the first time in this paper.

Anal fistula at roof of ischiorectal fossa inside levator-ani muscle (RIFIL): a new highly complex anal fistula diagnosed on MRI

BACKGROUND

As experience with anal fistula imaging (MRI) has increased, new pathways of fistula extension have been identified. A recently described pathway is the  'outer-sphincteric space' present between the external anal sphincter and its covering outer fascia. A new type of complex fistula is being described which is present in the outer-sphincteric space and continues superiorly along the lateral border of the external anal sphincter to the infero-lateral surface of the puborectalis and levator-ani. In effect, these outer-sphincteric fistulas are at the roof of the ischiorectal fossa inside the levator muscle (RIFIL). These fistulas are not transsphincteric fistulas as they remain inside the levator muscle and do not enter the ischiorectal fossa.

METHODS

The MRI scans of consecutive anal fistula patients operated over the last two years were analyzed retrospectively.

RESULTS

Of 419 operated fistula patients analyzed, 42(10%) had RIFIL and 377 non-RIFIL fistulas. Compared to non-RIFIL fistulas, there were significantly more recurrent, multiple tracts, horseshoe, supralevator, and suprasphincteric fistulas in the RIFIL group. RIFIL fistulas were significantly more complex than non-RIFIL fistulas(85.7% vs 38.5%, p < 0.00001) and the surgery failure rate was also significantly higher in the RIFIL group (30.6%) than in the non-RIFIL fistula (7.2%) group(p = 0.0001).

CONCLUSION

RIFIL are highly complex fistulas. Proper diagnosis by MRI, surgical access, and subsequent management of these fistulas is quite challenging and they are associated with poor prognosis. Missing their diagnosis would lead to higher recurrence rate. These have not been described previously and were perhaps confused with high transsphincteric infralevator fistulas in ischiorectal fossa.