Attending in Emergency Department(AED)

Recently one of our resident order a KUB for a 62F with epigastric pain which LMD diagnosed GB stone. His first impression is acute cholecystitis. After I visit the patient, PE showed severe epigastric pain with decreased bowel sound, muscle guarding and rebound pain. ED echo showed much air reflections in supine view but when I turned the patient to left decubitus view, there are several air reflections over right liver dome and without movements during respiration >> free air. Then I sent the patient for a chest left decubitus view and then a sitting Chest PA view. Finally the X rays showed much free air under right diaphragm which later prove to be PPU.
Epigastric pain + free air in left decubitus view by echo>> 100% subphrenic free air will be shown in either or both left decubitus view and/or sitting/standing Chest PA.

Suggestions:
1. For abd pain above the umbilicus>> order plain abdomen.
2. For abd pain below the umbilicus>> order KUB.
3. Abdominal ultrasound is the choice of examination in acute abdomen besides traditional X rays.
4. If the above measures didn't showed any free air, then an CT scan without contrast is needed to show the subphrenic free air.