This has always been a tricky situation. In the past 2 years I have seen 3 patients with clinical signs of peritonitis. They had a visibly normal looking X ray chest and Abdomen but Ultrasound revealed moderate amount of free fluid in abdomen. On closure inspection of X ray chest all the patients had strong suspicion of free gas under left dome of diaphragm, which was distinctly separate from the fundus gas shadow. This was later confirmed on plain CT abdomen. All patients had ileal perforation as the intra-abdominal finding.
