European Radiology

, Volume 28, Issue 2, pp 673–682 | Cite as

How to differentiate acute pelvic inflammatory disease from acute appendicitis ? A decision tree based on CT findings

  • Kim El Hentour
  • Ingrid MilletEmail author
  • Emmanuelle Pages-Bouic
  • Fernanda Curros-Doyon
  • Nicolas Molinari
  • Patrice Taourel
Emergency Radiology



To construct a decision tree based on CT findings to differentiate acute pelvic inflammatory disease (PID) from acute appendicitis (AA) in women with lower abdominal pain and inflammatory syndrome.

Materials and methods

This retrospective study was approved by our institutional review board and informed consent was waived. Contrast-enhanced CT studies of 109 women with acute PID and 218 age-matched women with AA were retrospectively and independently reviewed by two radiologists to identify CT findings predictive of PID or AA. Surgical and laboratory data were used for the PID and AA reference standard. Appropriate tests were performed to compare PID and AA and a CT decision tree using the classification and regression tree (CART) algorithm was generated.


The median patient age was 28 years (interquartile range, 22–39 years). According to the decision tree, an appendiceal diameter ≥ 7 mm was the most discriminating criterion for differentiating acute PID and AA, followed by a left tubal diameter ≥ 10 mm, with a global accuracy of 98.2 % (95 % CI: 96–99.4).


Appendiceal diameter and left tubal thickening are the most discriminating CT criteria for differentiating acute PID from AA.

Key points

• Appendiceal diameter and marked left tubal thickening allow differentiating PID from AA.

• PID should be considered if appendiceal diameter is < 7 mm.

• Marked left tubal diameter indicates PID rather than AA when enlarged appendix.

• No pathological CT findings were identified in 5 % of PID patients.


Pelvic inflammatory disease Computed tomography Appendicitis Fallopian tube Salpingitis 



Acute appendicitis


Classification and regression tree


C-reactive protein


Computed tomography


International classification of diseases


Interquartile range


Intrauterine device


Pelvic inflammatory disease


Tubo-ovarian abscess


Compliance with ethical standards


The scientific guarantor of this publication is Patrice Taourel.

Conflict of interest

The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.


The authors state that this work has not received any funding.

Statistics and biometry

Dr Molinari Nicolas kindly provided statistical advice for this manuscript.

Informed consent

Written informed consent was waived by the Institutional Review Board.

Ethical approval

Institutional Review Board approval was obtained.


• retrospective

• diagnostic study

• performed at one institution


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Copyright information

© European Society of Radiology 2017

Authors and Affiliations

  • Kim El Hentour
    • 1
  • Ingrid Millet
    • 1
    Email author
  • Emmanuelle Pages-Bouic
    • 1
  • Fernanda Curros-Doyon
    • 1
  • Nicolas Molinari
    • 2
  • Patrice Taourel
    • 1
  1. 1.Department of Medical ImagingLapeyronie HospitalMontpellierFrance
  2. 2.Department of Medical Information and StatisticsUMR 5149 IMAG, CHUMontpellierFrance

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