portal vein gas-peri
phery of liver, gets there by a breach in the bowel wall. usually associated with pneumatosis intestinalis
distinguishing small bowel from colon
transverse lines go all the way across small bowel (valvulae connivenites)
Fig. 1. A supine plain film radiograph showing that the Rigler sign or double-wall sign, which is visible as gas outlining both sides of the bowel wall, appeared as a thin and white stripe (black arrows). The periphery of the film shows that air trapped between adjacent loops of bowel is also visible as the telltale triangle sign (white arrows).
| | |