Gastric volvulus (Latin volvere, to roll) is rotation of all or part of the stomach by more than 180º, which may lead to a closed-loop obstruction and possible strangulation. (See the images below.) [1, 2, 3]
Symptoms may range from mild abdominal pain and vomiting, when no or partial outlet obstruction is present, to severe pain and retching, when there is complete obstruction and ischemia. 
The definitive diagnosis of gastric volvulus resides with the radiologist. Typically, the first examination to be performed in the patient with symptoms referable to the chest and/or abdomen is a plain radiograph. Although this is a good examination to start with, the most definitive study is the upper GI barium study. [3, 4, 5, 6] Plain radiography may demonstrate findings that are indistinguishable from those that are produced by other causes of gastric atony or obstruction. However, the modality is useful for excluding other causes of the patient's symptoms, such as pneumoperitoneum or pneumothorax. 
Barium study is highly sensitive and specific. However, the diagnosis may be missed in cases of intermittent torsion. Fiberoptic endoscopy has a limited role in the diagnosis of gastric volvulus because the twist precludes passage of the endoscope.
Laboratory studies are generally unrewarding, although levels of amylase and alkaline phosphatase may be increased.
In mesenteroaxial volvulus, the distended stomach appears spherical on supine images. Two air-fluid levels are visible on the upright film: 1 in the fundus, which is inferior, and 1 in the antrum, which is superior. In addition, the upright image often demonstrates a beak where the esophagogastric junction is seen on normal images. If a nasogastric tube is passed, the esophagogastric junction is seen inferior to its normal location. If barium moves past the esophagogastric junction, the upside-down configuration of the stomach and the degree of obstruction can be documented.
Organoaxial volvulus is difficult to diagnose on plain images. The stomach lies horizontally and contains a single air-fluid level on upright views. No characteristic beak is observed. Decreased air is noted within the remaining GI tract. Barium study shows that the esophagogastric junction is lower than normal. Marked gastric dilatation and the slow passage of contrast material past the site of twisting are noted.
See the images below for the radiographic characteristics of gastric volvulus.
Plain radiographic findings that are suggestive of gastric volvulus should be confirmed with a barium study.
Although the classic plain radiographic findings described above are suggestive of volvulus, a false-negative diagnosis may result if the twisted stomach is filled with fluid. A distended, air-filled stomach may result secondary to other causes of gastric obstruction, leading to a false-positive diagnosis.
The barium study is highly sensitive and specific for gastric volvulus. It is generally considered to be the criterion standard for diagnosis. However, as stated above, the diagnosis may be missed in cases of intermittent torsion. The upper GI series may show only a paraesophageal hernia or eventration of the diaphragm during a symptom-free interval, leading to a false-negative diagnosis.
The computed tomography (CT) scanning and magnetic resonance imaging (MRI) appearance of gastric volvulus can be variable. The extent of diaphragmatic herniation, the points of torsion, and the final position of the stomach determine the appearance. [8, 9, 10]
CT scanning and MRI are not typically considered to be the diagnostic examinations of choice in patients who are evaluated for gastric volvulus. However, some experts argue that the multiaxial reconstructions that are afforded by helical CT in particular may be preferred to the images obtained with conventional barium study, particularly in the acutely ill patient who is unable to tolerate a fluoroscopic examination. In addition, chronic gastric volvulus is often discovered incidentally in patients undergoing CT scanning for an unrelated condition. In most patients, CT scan or MRI findings that suggest a gastric volvulus should be confirmed with an upper GI series.
Without torsion, gastric volvulus may be difficult to distinguish from paraesophageal hiatal hernia, and false-positive, as well as false-negative, diagnoses can result.
Ultrasonography is a noninvasive modality that can be performed on debilitated patients relatively easily and repeatedly; it requires no specific preparation. However, ultrasonography as a technique for the detection of gastric disease (and of gastric volvulus in particular) is still in its infancy.
A study has demonstrated the peanut sign in a case of chronic gastric volvulus. The ultrasonographic features consist of a constricted segment of stomach, with 2 dilated segments located above and below the constricted part, akin to a peanut.  In several case reports, however, the ultrasonographic evaluation of gastric volvulus showed normal findings. Until more data are available, upper GI series should be used to confirm the diagnosis.
Gastric volvulus may be discovered during scintigraphic examination, sometimes incidentally, as the cause of a patient's symptoms. However, scintigraphic evidence of gastric volvulus should be confirmed with an upper GI series.
In 1 case report, a technetium-99m pertechnetate Meckel scan obtained to assess chronic GI bleeding in a child demonstrated an intrathoracic stomach with the greater curvature superior to the lesser curvature. Another case report demonstrated similar findings during an iodine-131 whole-body scan in a patient with metastatic thyroid cancer. In each case, upper GI series confirmed an organoaxial volvulus.
During an episode of gastric volvulus, the arteries supplying the stomach are displaced according to the position of the stomach. Typically, the right and left gastroepiploic arteries are displaced high beneath the left hemidiaphragm. The right gastroduodenal artery also is displaced, and the left gastric artery appears to be coiled and shortened.
Angiography is often used in the evaluation of massive or refractory GI hemorrhage. Although it is a rare cause of such hemorrhage, gastric volvulus should be considered. The angiographic appearance is sensitive and specific during an acute episode.