Preoperative assessment of simple and complex anorectal fistulas: Tridimensional endoanal ultrasound? Magnetic resonance? Both?

  • Antonio Brillantino
  • Francesca IacobellisEmail author
  • Alfonso Reginelli
  • Luigi Monaco
  • Biagio Sodano
  • Giuseppe Tufano
  • Antonio Tufano
  • Mauro Maglio
  • Maurizio De Palma
  • Natale Di Martino
  • Adolfo Renzi
  • Roberto Grassi



The purpose of the study is to evaluate the diagnostic value of tridimensional endoanal ultrasound (3D-EAUS) and magnetic resonance (MR) in the preoperative assessment of both simple and complex anorectal fistulas.


All the patients referred for the treatment of anal fistulas were enrolled in this study and underwent, as preoperative assessment, anamnestic evaluation, clinical examination, and unenhanced and H2O2-enhanced 3D-EAUS and MR. The results of imaging evaluation were compared with surgical findings, considered as reference standard.


During the study period, 124 patients operated on for anal fistulas underwent complete preoperative imaging assessment. Perfect agreement between 3D-EAUS and surgery in the anal fistulas’ severity grading was found (K = 1). The fistulas were classified as simple in 68/126 (53.9%) and complex in 58/126 (46.03%) cases, according to fistulas’ Parks’ classification and the most recent American Guidelines. In both simple and complex anal fistulas, 3D-EAUS did not show a significantly higher accuracy in the evaluation of internal openings, if compared with MR (P = 0.47; McNemar’s Chi-square test). In the complex anal fistulas, MR showed a significantly higher accuracy in the evaluation of secondary extensions if compared with 3D-EAUS (P = 0.041; McNemar’s Chi-square test), whereas in the simple anal fistulas, no significant difference was found.


In the preoperative work-up of patients with anorectal fistulas, 3D-EAUS may represent the first-line diagnostic tool. In cases of fistulas classified as complex by 3D-EAUS, MR may be indicated as adjunctive diagnostic imaging examination, to more carefully describe the fistulas’ complete anatomy.


3D-EAUS Endoanal ultrasound Magnetic resonance Anal fistulas Anal abscess Diagnostic accuracy 



Tridimensional endoanal ultrasound


Magnetic resonance


Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical standards

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Italian Society of Medical Radiology 2019

Authors and Affiliations

  • Antonio Brillantino
    • 1
  • Francesca Iacobellis
    • 2
    Email author
  • Alfonso Reginelli
    • 2
  • Luigi Monaco
    • 3
  • Biagio Sodano
    • 4
  • Giuseppe Tufano
    • 4
  • Antonio Tufano
    • 4
  • Mauro Maglio
    • 1
  • Maurizio De Palma
    • 1
  • Natale Di Martino
    • 5
  • Adolfo Renzi
    • 6
  • Roberto Grassi
    • 2
  1. 1.Department of Surgery“A. Cardarelli” HospitalNaplesItaly
  2. 2.Department of RadiologyUniversity of Campania “L. Vanvitelli”NaplesItaly
  3. 3.Department of Surgery“Villa Esther” HospitalAvellinoItaly
  4. 4.Department of Surgery, “Pellegrini” HospitalASL NA1 CentroNaplesItaly
  5. 5.Department of SurgeryUniversity of Campania “L. Vanvitelli”NaplesItaly
  6. 6.“Villa delle Querce” HospitalNaplesItaly

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