Ultrasound can help diagnose pediatric appendicitis, but is not effective in differentiating between perforated and nonperforated appendicitis, according to a study published in the journal Radiology.
Researchers from Texas Children’s Hospital and Baylor College of Medicine, both in Houston, prospectively evaluated the diagnostic performance of ultrasound in differentiating perforated from nonperforated pediatric appendicitis and to investigate the association between specific US findings and perforation.
A total of 577 patients with a diagnosis of appendicitis were included in the study. All had undergone abdominal US studies for suspected pediatric appendicitis upon presentation at the facility. The US studies were reported by using a risk-stratified scoring system:
· 1 indicated a normal appendix;
· 2 indicated an incompletely visualized normal appendix;
· 3 indicated a nonvisualized appendix;
· 4 indicated equivocal;
· 5a indicated a nonperforated appendicitis; and
· 5b indicated a perforated appendicitis.
The diagnostic performance of the ultrasound studies designated 5a and 5b was calculated and the following ultrasound findings were correlated with perforation at multivariate analysis:
· Maximum appendiceal diameter;
· Wall thickness, loss of mural stratification;
· Periappendiceal fat inflammation;
· Periappendiceal fluid;
· Lumen contents; and
· Appendicolith presence.
The number of symptomatic days prior to presentation was recorded. Surgical diagnosis and clinical follow-up served as reference standards.
The findings showed of the 577 subjects, 468 were determined to have a score of 5a and 109 with a score of 5b. Appendicitis was correctly identified in 573 (99.3 percent) of the 577 patients. Ultrasound performance in the detection of perforated appendicitis (5b) was as follows:
· Sensitivity of 44.0 percent (80 of 182);
· Specificity of 93.1 percent (364 of 391);
· Positive predictive value of 74.8 percent (80 of 107); and
· Negative predictive value of 78.1 percent (364 of 466).
Statistically significant associations with perforated appendicitis were longer duration of symptoms, increased maximum diameter, simple periappendiceal fluid, complex periappendiceal fluid, fluid-filled lumen, and appendicolith.
The researchers concluded that while ultrasound was highly specific in diagnosing pediatric appendicitis, it was nonsensitive for perforated pediatric appendicitis. They did note, however, that several US findings are significantly associated with perforation, especially the presence of complex periappendiceal fluid.