Ultrasound reliable for diagnosing perforated appendicitis in kids

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 - ultrasound perforated appendicitis
11-year-old girl with acute perforated appendicitis. Ultrasound image shows shadowing appendicolith (arrow) in appendiceal lumen.
Source: AJR2013; 200:957-962

Diagnosis of perforated appendicitis in children can be made when an abscess is detected with ultrasound, according to a study published in the May issue of the American Journal of Roentgenology.

In addition to the finding of an abscess, sonographic findings of intraluminal appendicolith and loss of the submucosal echogenic layer of the appendix were also found to be associated with appendiceal perforation, according to Terry L. Levin, MD, of Albert Einstein College of Medicine in Bronx, N.Y., and colleagues.

“Our study showed that ultrasound of children is effective in diagnosing perforation of the appendix, thus it has the potential to replace and thereby reduce the number of CT examinations commonly performed in this situation,” wrote the authors.

Acute appendicitis is the most common condition requiring emergency surgery in children. While emergency surgery is indicated for nonperforated appendicitis, therapy for perforated appendicitis may be nonsurgical.

To determine the effectiveness of ultrasound at differentiating perforated from nonperforated appendicitis in children, Levin and colleagues conducted a retrospective study of 161 consecutively registered children (mean age of 11 years) who had acute appendicitis and had undergone ultrasound and appendectomy. The surgical report was used as the reference standard.

Results showed the perforation rate was significantly higher in children younger than eight years compared with older children, with rates of 62.5 percent and 29.5 percent, respectively, according to the authors.

An abscess on ultrasound was associated with perforations, featuring a sensitivity of 36.2 percent and a specificity of 99 percent.

“In children younger than 8 years, who tend to have perforation without abscess formation, the differentiation is more complicated,” wrote Levin and colleagues. “In that age group, the findings of an appendicolith, loss of the appendiceal echogenic submucosal layer, a large amount of periappendiceal echogenic fat, and free fluid in the Morrison pouch or pelvis are associated with perforation in a decreasing order of significance.” Loss of the echogenic submucosal layer should not be the sole finding for diagnosis, they added.

When compared to CT, the authors said the sensitivities of their sonographic findings are comparable to reported CT sensitivities of various findings. Some specificities between the two modalities were less favorable for ultrasound, but the sonographic finding of an appendicolith in younger children and an abscess in a child of any age had comparable specificities to CT.

“CT should be reserved for complicated cases in which the appendix is not identified or the presence or absence of perforation cannot be determined with ultrasound,” concluded Levin and colleagues.