X ray findings in children with abdominal pain

What abnormalities may appear on plain radiographs in children with abdominal pain? 

• The plain film should be assessed for “bones, stones, masses, and gas.” An appendicolith is present in only about 5% to 15% of patients with appendicitis.
• Other findings in appendicitis may include sentinel loop, air-fluid levels, fecolith, mass in right lower quadrant, and indistinct psoas margins with scoliosis toward the right.
• Rarely, a perforated appendix may produce pneumoperitoneum. Some renal calculi can be visualized on plain radiographs of the abdomen.
• The invaginating bowel of intussusception may be apparent as an intraluminal density, but the more common finding is a paucity of air in the right upper and lower quadrants.
• Multiple stacked, dilated loops of bowel with air-fluid levels and the absence of distal air may signify intestinal obstruction. Abdominal radiographs may show evidence of constipation, previously unsuspected, or foreign bodies (FBs) such as ingested magnets. 

Sources

Marin JR, Alpern ER: Abdominal pain in children. Emerg Med Clin North Am 2011; 29:401–428.