Rationale and Objectives
The aim of this study was to evaluate the predictive value of intraluminal air for appendiceal necrosis and/or perforation when not apparent on imaging. Additional factors of intraluminal appendicoliths, age, and gender were also assessed.
Materials and Methods
Patients with pathologically proven appendicitis who underwent multidetector computed tomographic imaging over a 3-year period ( n = 487) were retrospectively reviewed. Those with imaging evidence for perforation were excluded to create a study population of apparent uncomplicated acute appendicitis ( n = 374). Each scan was assessed for intraluminal appendiceal air and appendicoliths on multidetector computed tomography and compared against surgical and pathologic results for appendiceal necrosis and/or perforation.
Results
Image-occult necrosis or perforation was present in 17.4% (65 or 374) of the study cohort. Intraluminal air and appendicoliths were predictive variables by univariate logistic regression ( P = .001 and P ≤ .001, respectively), with odds ratios of 2.64 (95% confidence interval, 1.48–4.73) for intraluminal air and 2.67 (95% confidence interval, 1.55–4.61) for appendicoliths. Both remained independent variables on multivariate modeling despite multicollinearity. Increasing age was also predictive (odds ratio, 1.25; 95% confidence interval, 1.09–1.44; P = .002), whereas gender was not ( P = .472).
Conclusions
Intraluminal appendiceal air in the setting of acute appendicitis is a marker of perforated or necrotic appendicitis. Recognition of this finding in otherwise uncomplicated appendicitis at imaging should raise suspicion for image-occult perforation or necrosis.
Acute appendicitis is the most common abdominal surgical emergency in the United States, with >250,000 new cases diagnosed each year . Computed tomographic (CT) imaging has emerged as the preferred imaging modality for the diagnosis of appendicitis, especially in adults, because of its high accuracy, widespread availability, and lack of operator dependence . A recent study documented the increased utilization of CT imaging in adult patients with suspected appendicitis from 19% in 1998 to 93% in 2007 . CT imaging has an excellent performance profile, with sensitivities and specificities ranging from 94% to 98% for the diagnosis of acute appendicitis , and is accurate in the differentiation of perforated from nonperforated appendicitis .
Prompt diagnosis of acute appendicitis is critical, because treatment of appendicitis before perforation significantly decreases morbidity and mortality . In our experience, the presence of intraluminal air within the appendix may be helpful in this regard, because it represents a finding that suggests necrosis and perforation that may otherwise be unapparent at imaging. Although some studies have pointed to an association between intraluminal air and acute appendicitis , its relationship to a more serious situation has not been widely recognized to our knowledge, either clinically or in the literature (aside from a sporadic case report) . Indeed, the presence of intraluminal air has been used as a feature to argue against the diagnosis of acute appendicitis by confirmation of luminal patency. However, this represents a distinctly different situation whereby the appendix is otherwise normal in appearance without evidence of obstruction or inflammation. The primary purpose of this study was to evaluate the predictive value of intraluminal appendiceal air in the setting of acute appendicitis for the presence of appendiceal necrosis and/or perforation when not otherwise apparent at imaging. The secondary aims included investigating other potential predictive factors, including demographic variables of age and gender and the CT feature of the presence of an intraluminal appendicolith.
Materials and methods
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Patient Population
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CT Technique
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Image Analysis
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Ground Truth for Necrosis or Perforation
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Statistical Analysis
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Results
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Table 1
Characteristics of the Patients
Variable Entire Study Population Simple Appendicitis Advanced Appendicitis_P_ ∗ ( n = 374) ( n = 309) ( n = 65) Age (y), mean ± standard deviation 26.0 ± 17.6 24.4 ± 16.2 32.2 ± 22.5 .044 Gender .50 Male 205 172 33 Female 169 137 32 Intraluminal air 80/374 (21.4%) 56/309 (18.1%) 24/65 (36.9%) .001 Intraluminal appendicolith 134/374 (35.8%) 98/309 (31.7%) 36/65 (55.4%) <.001
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Discussion
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