Source:http://linkedlifedata.com/resource/umls/id/C0032320
MSH: A condition with trapped gas or air in the PERITONEAL CAVITY, usually secondary to perforation of the internal organs such as the LUNG and the GASTROINTESTINAL TRACT, or to recent surgery. Pneumoperitoneum may be purposely introduced to aid radiological examination.,NCI: The presence of air in the peritoneal cavity. Causes include perforated peptic ulcer, perforated bowel, and trauma.