title: Differentiation between right tubo-ovarian abscess and appendicitis using CT--a diagnostic challenge.
abstract: OBJECTIVE
  To determine CT features that can potentially differentiate right tubo-ovarian abscess (TOA) from acute appendicitis (AA; including abscess formation).
  
  
  METHODS
  The abdominal computed tomography (CT) images of 48 patients with right-sided TOA (average age 39.3 ± 9.8 years) and 80 patients (average age 53.5 ± 19.9 years) with AA (24 with peri-appendicular abscess) were retrospectively evaluated. Two experienced radiologists evaluated 12 CT signs (including enlarged, thickened wall ovary, appendix diameter and wall thickness, peri-appendicular fluid collection, adjacent bowel wall thickening, fat stranding, free fluid, and extraluminal gas) in consensus to categorize the studies as either TOA or AA. The diagnosis and the frequency of each of the signs were correlated with the surgical and clinical outcome.
  
  
  RESULTS
  Reviewers classified 92% cases correctly (TOA=85%, AA=96.3%), 3% incorrectly (TOA=6.3%, AA=1.3%); 5% were equivocal (TOA=8.3%, AA=2.5%). In the peri-appendicular abscess group reviewers were correct in 100%. Frequent findings in the TOA group were an abnormal ovary (87.5%), peri-ovarian fat stranding (58.3%), and recto-sigmoid wall thickening (37.5%). An abnormal appendix was observed in 2% of TOA patients. Frequent findings in the AA group were a thickened wall (32.5%) and distended (80%) appendix. Recto-sigmoid wall thickening was less frequent in AA (12.5%). The appendix was not identified in 45.8% of the TOA patients compared to 15% AA.
  
  
  CONCLUSIONS
  In the presence of a right lower quadrant inflammatory mass, peri-ovarian fat stranding, thickened recto-sigmoid wall, and a normal appearing caecum, in young patients favour the diagnosis of TOA. An unidentified appendix does not contribute to the differentiation between TOA and peri-appendicular abscess.
authors: Department of Diagnostic Imaging, The Sheba Medical Center, Tel-Hashomer, Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel. iriseshed@gmail.com
authors: I
authors: I
authors: Eshed
authors: O
authors: O
authors: Halshtok
authors: Z
authors: Z
authors: Erlich
authors: R
authors: R
authors: Mashiach
authors: M
authors: M
authors: Hertz
authors: M M
authors: MM
authors: Amitai
authors: O
authors: O
authors: Portnoy
authors: L
authors: L
authors: Guranda
authors: N
authors: N
authors: Hiller
authors: S
authors: S
authors: Apter
mesh_terms: D018784:Abdominal Abscess / Q000000981:diagnostic imaging* / Q000601:surgery; D000328:Adult; D001064:Appendicitis / Q000000981:diagnostic imaging* / Q000601:surgery; D003937:Diagnosis, Differential; D005184:Fallopian Tube Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008875:Middle Aged; D010049:Ovarian Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D000292:Pelvic Inflammatory Disease / Q000000981:diagnostic imaging* / Q000601:surgery; D011860:Radiography, Abdominal; D012189:Retrospective Studies; D012680:Sensitivity and Specificity