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Classification of acute appendicitis (CAA): treatment directed new classification based on imaging (ultrasound, computed tomography) and pathology

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Abstract

Purpose

Acute appendicitis (AA) is amongst the most common causes of acute abdominal pain. In spite of progress based on risk stratifications, “negative” appendectomies are performed in up to 30% of patients whilst the appendix perforates in others. Preoperative classification of AA based on imaging is therefore recommended. The aim was to classify AA based on imaging (ultrasound/US, computed tomography/CT), surgical pathology, and/or histopathology in order to differentiate between complicated and uncomplicated AA. A new classification of acute appendicitis (CAA) shall be illustrated by typical US and CT images and be employed in a diagnostic and therapeutic algorithm.

Methods

Medline, Embase, and the Cochrane Library were searched. Any study after 1970, which investigated clinical scores, pathology, US, CT, magnetic resonance imaging, and treatment of AA, was included. Typical images were taken from the author’s image database.

Results

Five main types of AA are defined, normal appendix (type 0), nonvisualised appendix (type X), uncomplicated AA (type 1), complicated AA without perforation (type 2), and complicated AA with perforation (type 3). The imaging modality is indicated by an additional letter, e.g., type p3b for free perforation on pathology. Standardised reporting of the appendix evaluation by US and CT is presented, as well as algorithms for AA management. Imaging features indicating imminent perforation, as well as likely recurrence, were both classified as complicated AA.

Conclusion

Imaging is mandatory in suspected AA. The CAA clearly separates uncomplicated from complicated forms of AA allowing nonoperative management in selected patients with uncomplicated forms of AA.

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Acknowledgement

We thank M. Knörzer for secretarial assistance and A. De Forrest, MD, and M.W. Hoffmann, MD PhD, for critical reading of the manuscript.

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Authors and Affiliations

  1. Medizinische Klinik I mit Schwerpunkt Gastroenterologie, Diabetologie, Rheumatologie und Onkologie, St. Marien- und St. Annastiftskrankenhaus, Salzburger Straße 15, D67067, Ludwigshafen, Germany

    Jörg C. Hoffmann & Claus-Peter Trimborn

  2. Klinik für Allgemein-, Viszeral- und Transplantationschirurgie, Universitätsklinikum Augsburg, Augsburg, Germany

    Michael Hoffmann & Matthias Anthuber

  3. Radiologische Klinik, St. Marien- und St. Annastiftskrankenhaus Ludwigshafen, Ludwigshafen, Germany

    Ralf Schröder

  4. Institut für Pathologie der Ruhr-Universität Bochum, Bochum, Germany

    Sarah Förster & Andrea Tannapfel

  5. Gastroenterologie, Allgemeine Innere Medizin und Geriatrie, Rems-Murr-Kliniken Winnenden, Winnenden, Germany

    Klaus Dirks

  6. Abteilung für Radiologie und Nuklearmedizin Krankenhaus der Barmherzigen Brüder Salzburg, Salzburg, Austria

    Alois Hollerweger

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Hoffmann, J.C., Trimborn, CP., Hoffmann, M. et al. Classification of acute appendicitis (CAA): treatment directed new classification based on imaging (ultrasound, computed tomography) and pathology. Int J Colorectal Dis 36, 2347–2360 (2021). https://doi.org/10.1007/s00384-021-03940-8

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