Objective: Abdominal pain is one of the most common causes of hospitalization in childhood. Here we aimed to evaluate the contribution of positive fi ndings in the upright abdominal x-ray and ultrasound imaging for the diagnosis of acute appendicitis in children admitted with abdominal pain.Material and Methods: The upright abdominal x-ray and ultrasound images of children who presented to our outpatient clinic with suspected acute appendicitis in 2010 were analyzed retrospectively. The patients were divided into 2 groups. The children with a fi nal diagnosis of acute appendicitis constituted group 1, while the patients who were operated on for suspected appendicitis and where the pathology examination was negative for appendicitis and children who required only observation in the hospital or as outpatient for suspected appendicitis made up group 2. Findings accepted to suggest a diagnosis of acute appendicitis on plain x-ray were air-fl uid level at the right lower quadrant, diffuse air-fl uid evels, presence of fecalith, blurring or loss of the properitoneal fat stripe, lumbar scoliosis with a left convexity, free air under the diaphragm,

and gas shadow in the appendix. The criterion for the diagnosis of appendicitis by US was detection of a non-compressible, fl uid-fi lled

and blind-ended tubular intestinal segment in connection with the cecum that was more than 6 mm in diameter. Furthermore, fi ndings that

support the diagnosis of appendicitis such as presence of an appendicolith, increased periappendiceal mesenteric echogenicity, presence

of abscess and conglomeration of intestinal loops to the right lower quadrant were also evaluated.

Results: A total of 744 patients presented at our outpatient clinic for suspected acute appendicitis during the year 2010. Group I

consisted of 350 and group II of 394 children. The mean age was comparable between the groups (p>0.05). Upright abdominal x-ray

was available for 87.5% and ultrasound imaging for 78.5% the patients. Only 59.4% of the ultrasound examinations were carried out by

our institution’s radiology department while the rest (40.6%) were performed elsewhere. In group I, the fi ndings on plain abdominal x-ray

suggestive of acute appendicitis were as follows; air-fl uid levels at right lower quadrant (46.8%), lumbar scoliosis with left-sided convexity

(10.5%), presence of fecalith (4.7%), and blurring of the right properitoneal fat shadow (4.1%). The sensitivity of plain abdominal x-ray

for acute appendicitis was 56.3% with a specifi city of 66.9%. The diameter of the appendix could be measured only in 180 patients with

ultrasound imaging. An appendix diameter ≥ 6 mm could be used to diagnose appendicitis with 86.4% sensitivity while unresponsiveness

to compression could predict acute appendicitis with a sensitivity of 72.1%. In group I, appendicolith, abscess and increased mesenteric

echogenity on ultrasound imaging were found in 16.2%, 5.5% and 37.5% of the patients respectively. The total sensitivity and specifi city

of ultrasound imaging were 66.9% and 66.1% respectively.

Conclusion: Only half of the children with acute appendicitis have a positive fi nding on plain x-ray. Although variability exists depending on

the experience of the radiologist, ultrasound imaging is one of the most sensitive imaging modalities for the diagnosis of childhood acute

appendicitis. In conclusion, we believe that acute appendicitis cannot be diagnosed by relying solely on imaging features and correlation of

the imaging features with clinical parameters is essential.

Keywords: Appendicitis, Child, Abdominal radiography, Ultrasonography