Anal fistulae - Three-dimensional endoanal ultrasound and outcomes of collagen plug treatment

Research output: ThesisDoctoral Thesis (compilation)

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Background: The treatment of complex anal fistulae remains a therapeutic challenge. Early anal fistula plug (AFP) studies showed high success rates, while later reports demonstrated success rate of 13-100% at usual follow-up of 6-24 months. Very little is known about morphological findings related to success and failure of the AFP, especially if three-dimensional (3D) endoanal ultrasound (EAUS) is used for radiological follow-up. No documentation is available for the use of a high-resolution transducer for assessment of anal fistulae and anal canal length.

Aims: I: To evaluate the long-term success rate of the AFP in the treatment of complex anal fistulae. II: To explore the utilisation of 3D EAUS for the follow-up of the AFP. III: To evaluate the accuracy of 3D EAUS alone for assessment of newly diagnosed cryptoglandular fistulae, compared to intraoperative findings in combination with intraoperative 3D EAUS (gold standard). IV: To explore the use of 3D EAUS for the measurement of anal canal length in patients with newly diagnosed cryptoglandular fistulae.

Methods: Two prospective cohort study projects, each designed to produce two papers. Papers I & II: A single-centre study of consecutive patients with complex anal fistulae treated in May 2006-October 2009. Patients with ano/rectovaginal fistulas were excluded. Papers III & IV: A single-centre study of consecutive patients with newly diagnosed cryptoglandular anal fistulae and no history of fistula surgery treated between June 2018-March 2020. Patients with inflammatory bowel disease, ano/rectovaginal fistulae, more than one fistula, or a fistula with more than one internal orifice (IO) were excluded.

Main outcomes: Paper I: AFP success rate >7 years postoperatively, Paper II: Morphological 3D EAUS findings and relation to AFP failure, Paper III: Agreement between 3D EAUS alone and the gold standard, Paper IV: the mean anal canal length in female and male with transducers 2052 and 8838.

Results and conclusions: Paper I: The overall success rate 93-138 months after the AFP was 38%. It is acceptable considering the low morbidity of the procedure in a complex disease with high recurrence rates over time.
Paper II: 3D EAUS may be utilised for AFP follow-up. Postoperative 3D EAUS at three months or later, especially in combination with clinical symptoms, can be used to predict long-term AFP failure.
Paper III: 3D EAUS alone has high precision in identifying IO of anal fistulae. The method may be utilised even by relatively inexperienced surgeons to identify fistulae suitable for fistulotomy.
Paper IV: Measurements of anal canal length in female and male patients assessed by two different transducers for 3D EAUS are reported with generally acceptable reproducibility and repeatability.
Translated title of the contributionAnala fistlar: Tredimensionellt endoanalt ultraljud och resultat av behandling med kollagenplugg
Original languageEnglish
Awarding Institution
  • Department of Clinical Sciences, Malmö
  • Regnér, Sara, Supervisor
  • Johnson, Louis Banka, Assistant supervisor
  • Starck-Söndergaard, Marianne, Assistant supervisor
Award date2023 Dec 1
Place of PublicationLund
ISBN (Print)978-91-8021-480-3
Publication statusPublished - 2023

Bibliographical note

Defence details
Date: 2023-12-01
Time: 09:00
Place: Lilla aulan, Jan Waldenströms gata 5, Skånes Universitetssjukhus i Malmö
External reviewer(s)
Name: Myrelid, Pär
Title: Associate Professor
Affiliation: Division of Surgery, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, University Hospital Linköping

Subject classification (UKÄ)

  • Surgery

Free keywords

  • anal fistula
  • Crohn's disease
  • cryptoglandular fistula
  • anal fistula plug
  • Complex anal fistula
  • three-dimensional endoanal ultrasound
  • anal canal length
  • anal canal anatomy


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