A CT scan will show the distended loops quite well. Look for collapsed bowel and follow it proximally to the distended area. This will be evidence of obstruction and will point to the site of obstruction.
With a CT it may be possible to see enlarged lymph glands or evidence of metastatic disease in the liver or peritoneum.
|Modality||Sensitivity (%)||Specificity (%)|
|CT with oral contrast||100||83|
Sometimes the plain film will not show evidence of intestinal obstruction because the loops do not have much gas in them. Obstruction is usually obvious on a CT scan, see table 12.
Rarer causes of obstruction may be diagnosed pre-operatively on CT scanning. For instance, Spigelian hernia6 or an unsuspected laparoscopic port site hernia.