May Be Caused by

 Common

Bowel infarction

Bronchoscopy

Crohn disease

Diagnostic pneumoperitoneum

Endoscopy

Intestinal obstruction

Perforated GI tract neoplasm

Perforated peptic ulcer

Peritoneal dialysis

Postoperative state

Respiratory therapy

Rubin test

Vaginal aspiration

 Uncommon

Aerophagia

Distention of stomach

Gastroscopy

Idiopathic dilatation of colon

Jejunal diverticulosis

Misplaced oxygen tube

Pneumatosis cystoides intestinalis

Pneumomediastinum

Pneumothorax via congenital pleuroperitoneal fistula

Pulmonary emphysema

Ruptured bulla

Sclerotherapy of esophageal varices

Sodium bicarbonate ingestion