Low-dose CT is an effective way to diagnose or exclude appendicitis. Ultrasonography is another valuable tool.
When ultrasonography is used, a normal appendix may be seen in up to 50% of children with abdominal pain and the clinical question of appendicitis. Visualization of a normal appendix measuring less that 6 mm in diameter excludes appendicitis (figure 1). An enlarged appendix that does not compress is diagnostic of appenidicitis (figure 2). In those children in whom the appendix cannot be identified or with complications from appendicitis, obeservation by the doctor or CT is the next step. In some institutions, MRI is used for appendicitis.
Fluoroscopic enema is an effective way to diagnose, exclude, and treat intussusception (a condition in which a part of the bowel "telescopes" into another part of the bowel). The majority of children with clinically suspected intussusception do not have intussusception. There is no way for your doctor to diagnose intussusception because less than 30% of patients with intussusception have the typical findings of abdominal mass, colicky abdominal pain, and currant jelly stool. Ultrasonography is a reliable screening method for diagnosis and exclusion of intussusception (figure 3).
In children, diagnosis of empyema (infection around the lung) with CT is difficult. The wall of the lung (pleura) may not enhance after intravenous contrast administration (a material injected in the vein to see the orans better), and the contour of the collection may be the same as simple pleural effusion. On ultrasonograms, pleural loculations and debris-containing fluid (pleural effusion) are readily identified (figure 4).