Achieving a high cure rate in complex anal fistulas: understanding the conceptual role of the Garg cardinal principles
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We read with great interest the article by Abbas et al. [1], in which they discussed their excellent results with fistulotomy with immediate primary sphincteroplasty (FIPS) and demonstrated that the outcomes of FIPS are comparable to those of fistulotomy alone. However, there are a few questions and relevant points that we believe merit further discussion based on our experience.
The authors performed a fistulotomy followed by immediate primary sphincteroplasty (FIPS), a procedure that is technically distinct from fistulectomy with primary sphincter repair (FPR). However, the authors did not clearly differentiate between these 2 techniques. In the discussion, the term FIPS is used while citing papers on FPR. Furthermore, Table 3 is titled "Summary of studies reporting the results of FIPS," yet of the 20 studies listed, 17 pertain to FPR and only 3 to FIPS [1].
FPR was initially described by Parkash et al. [2] in 1985, while the first description of FIPS was published by Ratto et al. [3] in 2013. In a systematic review conducted by Ratto et al. [4] in 2015, which aimed to evaluate the literature on fistulotomy or fistulectomy and primary sphincter reconstruction, they identified 14 studies involving FPR and only 1 involving FIPS. It was not until the publication of the first study on FIPS in 2013 [3], and subsequent research in 2019 [5], that the procedure became more common [6].
FIPS and FPR are conceptually similar surgical procedures with comparable outcomes, but it is important to recognize that they differ technically. In FPR, a fistulectomy is performed, involving the complete removal of the fistula tract. In contrast, FIPS involves a fistulotomy, where the fistula tract is merely opened, cleaned, and curetted without completely excising its posterior wall. Technically, a fistulotomy is easier to perform than a fistulectomy. Initially, there was concern that performing a fistulotomy without sphincter repair and without fully excising all tracts might lead to increased septic complications and recurrence rates. However, these concerns were mitigated by the findings of Litta et al. [5] in 2019, and further supported by the study in question [1], which demonstrated that FIPS does not lead to an increase in septic complications and has a success rate comparable to that of FPR.
In the study conducted by Abbas et al. [1], suprasphincteric fistulas were present in both groups, with 5 out of 45 cases in the FIPS group and 4 out of 107 in the fistulotomy group. This finding is notable because a suprasphincteric fistula encompasses the entire external anal sphincter, making it an absolute contraindication for fistulotomy and a strong contraindication for FIPS. Performing a fistulotomy or even FIPS on a suprasphincteric fistula would necessitate cutting through the entire external anal sphincter, an approach that is neither logical nor recommended. Similarly, Litta et al. [5] excluded suprasphincteric fistulas from their study on FIPS.
Over the past 15 years, several gadget-based sphincter-sparing procedures have been introduced, including video-assisted anal fistula treatment (VAAFT), fistula-tract laser closure (FiLac), fixcision, anal fistula plug (AFP), over-the-scope clip (OTSC), and stem cell treatments. However, their success rates in treating high complex fistulas are not promising, ranging from 25% to 65% [7]. In contrast, studies on FIPS and FPR have consistently shown high success rates in high complex fistulas. It would be pertinent to analyze the pathophysiological basis behind the high success rate of FIPS and FPR, and this understanding is provided by the 3 Garg cardinal principles for managing complex fistula in ano [8, 9].
The 3 cardinal principles are ISTAC (intersphincteric tract acts like an abscess in a closed space), DRAPED (drainage of all pus and ensuring continued drainage in the postoperative period till complete healing occurs), and HOPTIC (healing occurs progressively till it is interrupted irreversibly by a collection) [8].
ISTAC implies that a fistula tract in the intersphincteric space, confined by 2 anal sphincter muscles, behaves similarly to an abscess and should therefore be drained and treated as such. DRAPED highlights the necessity of evacuating pus and maintaining effective drainage until complete healing is achieved. HOPTIC indicates that the healing process is ongoing unless it is halted or permanently obstructed by an accumulation of pus or serous fluid. A surgical procedure adhering to these 3 principles is likely to be highly effective in treating complex fistulas. Conversely, ignoring these principles may result in lower success rates [8].
Once these principles are understood, it becomes clear why recent gadget-based sphincter-sparing procedures (VAAFT, FiLac, fixcision, AFP, OTSC, etc.) yield poor outcomes in treating high complex fistulas. These procedures fail to adhere to the ISTAC principle, which involves addressing the intersphincteric portion of the fistula tract; instead, they focus solely on managing the external tracts and the internal opening. Consequently, most simple fistulas, which typically lack a significant intersphincteric portion, see a moderate success rate of 50% to 75% with these procedures. The ligation of intersphincteric tract (LIFT) procedure addresses the ISTAC principle by opening and cleaning the intersphincteric tract and space. However, it neglects the second principle, DRAPED, as it allows the opened-up intersphincteric tract to collapse and close during the postoperative period. This oversight results in a moderate success rate of 50% to 75% in complex fistulas. A recently described procedure, transanal opening of intersphincteric space (TROPIS) [10, 11], effectively addresses both the ISTAC and DRAPED principles. It involves deroofing the intersphincteric portion of the fistula tract through the transanal route, allowing it to heal by secondary intention. A recent meta-analysis has shown that among all sphincter-preserving procedures, TROPIS achieved the highest cure rate (85%–92%) [7]. In the FPR/FIPS procedures, the intersphincteric portion of the fistula tract is excised, laid open, and allowed to heal by secondary intention in fistulotomy. This approach adheres to both the ISTAC and DRAPED principles, resulting in a high success rate.
The Garg cardinal principles offer valuable insights into which procedures are more effective for treating high complexity fistulas. These principles should be considered when developing new methods to manage complex fistulas.
Notes
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