Both xrays show markedly dilated loops of small bowel, and a dilated transverse colon is seen on the chest xray. The chest xray is taken standing up (erect) and shows air-fluid levels in both the small and large bowel. On the abdominal xray, there is no gas seen in the large bowel beyond the splenic flexure. The findings indicate small and large bowel obstruction.
The transition point appears to be just beyond the splenic flexure on the chest xray. A focussed view of the upper abdomen was also taken as part of the abdominal series:
This view confirms a transition point at the proximal descending colon - indicated by a sudden change in distension of the colon from being gas-filled to completely collapsed. This is known as the colon cut-off sign.
A CT of the chest, abdomen and pelvis should be the next step as the findings are suspicious for a colonic malignancy.
The CT confirms a tight stricture involving the proximal descending colon with marked proximal colonic distension.
The colon cut-off sign has been described most commonly with acute pancreatitis, secondary to the inflammation extending to the splenic flexure via the phrenicocolic ligament. However, the degree of distension is not as much as in a true colonic stricture, with much of the small bowel distension in pancreatitis being due to an ileus. If you see this pattern of xray findings in somebody with abdominal distension without features of acute pancreatitis, a malignant stricture should be suspected and CT of the chest, abdomen and pelvis arranged.