How does the Parks classification compare with the AGA classification in predicting surgical outcomes for perianal CD fistulas

What is known

- Parks classifies tracts anatomically (intersphincteric, transsphincteric, suprasphincteric, extrasphincteric; modified to add superficial/submucosal) but does not capture secondary tracts, abscess, or proctitis. ^1–4 - The AGA system divides fistulas into simple vs complex using tract anatomy, number of external openings, and complicating features (abscess, proctitis, stricture, rectovaginal involvement). ^2,5,6 - AGA complexity has prognostic relevance — complex fistulas achieve remission less often and undergo more procedures (median 6 vs 3) than simple fistulas. ^2,7 - Parks is regarded as most useful when combined with internal/external opening location and abscess severity, rather than as a standalone outcome predictor. ⁷

What is unknown / caveats

- No head-to-head study of Parks vs AGA for surgical outcome prediction in the retrieved evidence - AGA 'complex' category aggregates multiple variables and does not permit individualized treatment stratification - Retrieved sources are reviews/guidelines, not comparative outcome cohorts - The excerpts describe the two systems' properties but do not quantify their comparative predictive accuracy for surgical outcomes.

## References

1. Pelly T, Anand E, Hanna L, Shakweh E, Joshi S, Lung P, Hart A, Tozer P. Time to classify: a narrative and scoping review of the old and the new classifications of perianal Crohn's disease. Tech Coloproctol. 2025;29(1):123. PMID: 40419817.

2. Lee JL, Yoon YS, Yu CS. Treatment Strategy for Perianal Fistulas in Crohn Disease Patients: The Surgeon's Point of View. Ann Coloproctol. 2021;37(1):5-15. PMID: 33730796.

3. American Gastroenterological Association Clinical Practice C. American Gastroenterological Association medical position statement: perianal Crohn's disease. Gastroenterology. 2003;125(5):1503-7. PMID: 14598267.

4. Gecse K, Khanna R, Stoker J, Jenkins JT, Gabe S, Hahnloser D, D'Haens G. Fistulizing Crohn's disease: Diagnosis and management. United European Gastroenterol J. 2013;1(3):206-13. PMID: 24917961.

5. Lan N, Wu X, Shen B. Stem cell therapy: light in the tunnel for penetrating Crohn's disease. Gastroenterol Rep (Oxf). 2023;11:goac085. PMID: 36974084.

6. Cho WJ, Wong SY. A Guide Through the Tunnel: Updates in the Approach to Classification and Management of Perianal Fistulizing Crohn's Disease. Curr Gastroenterol Rep. 2025;27(1):46. PMID: 40576852.

7. Householder S, Picoraro JA. Diagnosis and Classification of Fistula from Inflammatory Bowel Disease and Inflammatory Bowel Disease-Related Surgery. Gastrointest Endosc Clin N Am. 2022;32(4):631-650. PMID: 36202507.

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_Draft — generated by the IBDology RAG and not yet clinician-reviewed. Answers are grounded in the retrieved literature listed above; a high faithfulness score means the answer matches its sources, not that the sources are correct._