Comparison of Preoperative and Postoperative MRI After Fistula-in-Ano Surgery: Lessons Learnt from An Audit of 1323 MRI At a Single Centre

  • Pankaj GargEmail author
Original Scientific Report



Several studies have evaluated the efficacy of preoperative MRI in fistula-in-ano. However, the evaluation of MRI after fistula-in-ano surgery has never been done. The aim was to evaluate the utility of MRI in postoperative period after fistula-in-ano surgery.


Preoperative MRI was done in all the patients presenting with fistula-in-ano. Postoperative MRI was done to check radiological healing in clinically healed fistulas or when postoperative complication/healing problem was seen. The postoperative MRI was compared with preoperative MRI and correlated with the clinical picture.


A total of 1323 MRI were done in 1003 fistula-in-ano patients, out of which 702 patients underwent surgery. In 702 patients, there were 361 recurrent fistulas, 153 had associated abscess, 388 had multiple tracts, 146 had horseshoe tract, and 76 had supralevator fistula. In total, 320 postoperative MRI scans were done in 180/702 patients. The requirement of postoperative MRI was significantly higher in complex (grades III–V) than simple fistulas (grades I–II) [43.5% (136/313) vs. 11.3% (44/389), respectively, P < 0.0001]. In early postoperative period (8 weeks), healing (granulation) tissue was difficult to differentiate from active fistula tract/pus. The complete radiological healing took at least 10–12 weeks. So getting MRI scan for the assessment of healing was more accurate after 12 weeks. MRI was very accurate to identify postoperative complications like abscess, missed tract or non-healing of a tract. MRI detected such complications even in apparently clinically healed tracts. Closure/healing of internal opening and intersphincteric tract was assessed accurately by MRI and correlated well with the fistula healing.


MRI is highly useful to assess healing and detect complications after fistula surgery.



The author acknowledges the contribution of Dr Baljit kaur, the radiologist, who analysed all the MRI scans with the author.

Author’s contributions

Pankaj Garg contributed to concept, study design, acquisition of data, analysis of data, drafting, revising, final approval of the draft, submission of manuscript.

Compliance with ethical standards

Conflict of interest

All authors have declared that they have no conflicts of interest.


  1. 1.
    Garg P, Singh P, Kaur B (2017) Magnetic resonance imaging (MRI): operative findings correlation in 229 fistula-in-ano patients. World J Surg 41:1618–1624. CrossRefGoogle Scholar
  2. 2.
    Siddiqui MR, Ashrafian H, Tozer P et al (2012) A diagnostic accuracy meta-analysis of endoanal ultrasound and MRI for perianal fistula assessment. Dis Colon Rectum 55:576–585CrossRefGoogle Scholar
  3. 3.
    Halligan S, Stoker J (2006) Imaging of fistula in ano. Radiology 239:18–33CrossRefGoogle Scholar
  4. 4.
    Garg P (2018) Understanding and treating supralevator Fistula-in-Ano: MRI analysis of 51 cases and a review of literature. Dis Colon Rectum 61:612–621CrossRefGoogle Scholar
  5. 5.
    Garg P (2018) Is fistulotomy still the gold standard in present era and is it highly underutilized?: An audit of 675 operated cases. Int J Surg 56:26–30CrossRefGoogle Scholar
  6. 6.
    Garg P (2017) Transanal opening of intersphincteric space (TROPIS)—a new procedure to treat high complex anal fistula. Int J Surg 40:130–134CrossRefGoogle Scholar
  7. 7.
    Garg P (2017) Comparing existing classifications of fistula-in-ano in 440 operated patients: is it time for a new classification? Int J Surg 42:34–40CrossRefGoogle Scholar
  8. 8.
    Morris J, Spencer JA, Ambrose NS (2000) MR imaging classification of perianal fistulas and its implications for patient management. Radiographics 20:623–635 discussion 35–7 CrossRefGoogle Scholar
  9. 9.
    Parks AG, Gordon PH, Hardcastle JD (1976) A classification of fistula-in-ano. Br J Surg 63:1–12CrossRefGoogle Scholar
  10. 10.
    Garg P (2018) Garg classification for anal fistulas: Is it better than existing classifications?—a review. Indian J Surg 80:606–608. CrossRefGoogle Scholar
  11. 11.
    Garg P (2018) Intersphincteric component in a complex fistula-in-ano is like an abscess and should be treated like one. Dis Colon Rectum 61:e26CrossRefGoogle Scholar
  12. 12.
    Garg P, Begani M, Ladha A, Garg M (2018) Intersphincteric component in complex fistula-in-ano is like an abscess and should be treated like one: transanal opening of intersphincteric space (TROPIS) procedure in 158 highly complex anal fistulas. Dis Colon Rectum 61:E245CrossRefGoogle Scholar
  13. 13.
    Garg P (2016) Supralevator extension in fistula-in-ano is almost always in the intersphincteric plane: easy solution for a complex disease. Dis Colon Rectum 59:e41–e42CrossRefGoogle Scholar
  14. 14.
    Lefrancois P, Zummo-Soucy M, Olivie D et al (2018) Diagnostic performance of intravoxel incoherent motion diffusion-weighted imaging and dynamic contrast-enhanced MRI for assessment of anal fistula activity. PLoS ONE 13:e0191822CrossRefGoogle Scholar
  15. 15.
    Lam D, Yong E, D’Souza B, Woods R (2018) Three-dimensional modeling for Crohn’s Fistula-in-Ano: a novel, interactive approach. Dis Colon Rectum 61:567–572CrossRefGoogle Scholar

Copyright information

© Société Internationale de Chirurgie 2019

Authors and Affiliations

  1. 1.Indus Super Specialty HospitalMohaliIndia
  2. 2.Garg Fistula Research InstitutePanchkulaIndia

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