Upper GI studies
The diagnosis of gastric volvulus is usually based on barium studies; however, some authors recommend computed tomography (CT) scanning as the imaging modality of choice. Upper gastrointestinal (GI) contrast radiographic studies (using barium or Gastrografin) are sensitive and specific if performed with the stomach in the "twisted" state and may show an upside-down stomach. Contrast studies have been reported to have a diagnostic yield in 81–84% of patients. Often performed for an evaluation of acute abdominal pain, a computed tomography (CT) scan can offer immediate diagnosis by showing two bubbles with a transition line. Proponents of CT scanning in the diagnosis of gastric volvulus report several benefits, including: 

the ability to rapidly diagnose the condition based on a few coronal reconstructed images,
the ability to detect the presence or absence of gastric pneumatosis and free air,
the detection of predisposing factors (i.e., diaphragmatic or hiatal hernias), and
the exclusion of other abdominal pathology. Endoscopy
Upper gastrointestinal (GI) endoscopy may be helpful in the diagnosis of gastric volvulus. When this procedure reveals distortion of the gastric anatomy with difficulty intubating the stomach or pylorus, it can be highly suggestive of gastric volvulus. In the late stage of gastric volvulus, strangulation of the blood supply can result in progressive ischemic ulceration or mucosal fissuring. The nonoperative mortality rate for gastric volvulus is reportedly as high as 80%. Historically, mortality rates of 30–50% have been reported for acute gastric volvulus, with the major cause of death being strangulation, which can lead to necrosis and perforation.
With advances in diagnosis and management, the mortality rate from acute gastric volvulus is 15–20% and that for chronic gastric volvulus is 0–13%. References
External links

Schaefer D, Nikoomenesh P, Moore C (1997). "Gastric volvulus: an old disease process with some new twists". Gastroenterologist. 5 (1): 41–5. PMID 9074918.