In the absence of obvious symptoms of acute abdomen, what is the situation of finding free gas under the diaphragm?

Peritonitis usually occurs immediately after gastrointestinal perforation. After about 10 hour, the bacteria proliferated and gradually became bacterial peritonitis, mostly diffuse. If the patient gets better after 24 hours, peritonitis may be limited. ① Gastrointestinal perforation: Sometimes the clinical symptoms of peritonitis may not be obvious when the ulcer is perforated, and there are also people who have gastrointestinal perforation caused by gastrointestinal tumor or retroperitoneal tumor without obvious symptoms of peritonitis. At this time, we should actively check and pay close attention to the development of the disease; ② Small intestinal gas cyst: This kind of patients are sometimes found in outpatient fluoroscopy, and most of them are complicated with pyloric obstruction; ③ Pneumothorax: In a few cases of pneumothorax, the gas in the thoracic cavity can enter the abdominal cavity through the mediastinum; ④ Artificial pneumoperitoneum, recent after abdominal operation or after tubal ventilation: As long as the medical history is paid attention, this situation is not difficult to distinguish. It can be seen that the clinical significance of finding subphrenic free gas in abdominal fluoroscopy is obvious. Therefore, it is very important for X-ray doctors to determine whether there is subphrenic free gas. Use various postures, such as standing posture, and make a horizontal projection with the right side up when necessary to observe. Attention should be paid to the stable colon, diaphragmatic overlap and gastric vesicle, which should not be mistaken for free gas under the diaphragm. Generally speaking, gastrointestinal perforation has peritonitis symptoms and typical clinical signs, and it is also possible that X-ray fluoroscopy has not found free gas under the diaphragm. It depends on the location, size and time of the perforation.