The initial investigation for volvulus can be a plain x-ray without contrast, or a CT scan. CT scan is useful in diagnosing volvulus when x-ray has been unfruitful. CT can also identify the level of obstruction and determine if bowel necrosis has occurred.

• The abdominal CT should be performed when the patient presents with symptoms of abdominal pain, distension, constipation/obstipation and nausea.^[1][2]
• A CT scan can determine obstruction level, rule out other causes of abdominal pain and obstruction, and when pathology is not clear with a plain x-ray.
  • The following result of abdominal CT is indicative of volvulus:
    • Sigmoid, cecal, ileal volvulus:
      • Whirl pattern signifying a dilated bowel
      • Bird beak appearance of afferent and efferent colonic segments
      • Absence of rectal gas
      • Separation of the sigmoid walls by adjacent mesenteric fat (split wall sign)
    • Additional findings suggestive of bowel necrosis on CT:
      • Presence of air in the intestines (pneumatosis intestinalis)
      • Portal venous gas
      • Loss of bowel wall enhancement
• In addition to these findings, a CT scan may be useful in determining the following:
  • Diaphragmatic defects
  • Free air or fluid in the abdomen
  • Other sources of symptoms within the abdominal cavity