Abdominal pain out of proportion to exam.
Can you determine what is the abnormal structure?
Esophagus.Stomach.Pericardium.Left lower lobe.Liver.
CXR: Abnormal cardiomediastinal silhouette, with apparent enlargement of the heart size. Large, rounded, double density with internal lucency that projects over the mediastinal contours Associated soft tissue density, seen best in the retrocardiac region on the lateral view of the chest, with absolute measurements difficult to determine. Intrathoracic mass is noted to splay the carina, with elevation of both the left and right mainstem bronchi. Associated airspace disease, likely passive atelectasis.
CT abd: Herniation of the stomach and proximal portion of the duodenum through the diaphragmatic hiatus into the chest. Twisting of the bowel within the chest near the diaphragm, likely within the distal stomach A few small pockets of extraluminal gas Duodenum is stretched and collapsed. Shift of the midline structures within the upper abdomen slightly to the left with stretching of the splenic and hepatic arteries. No discrete luminal obstruction. Significant surrounding mesenteric stranding extending into the abdomen with fluid tracking down within the subphrenic spaces.
Gastric volvulus is a relatively condition in which the stomach twists upon itself, potentially resulting in obstruction or life-threatening ischemia. Two basic categories of gastric volvulus exist: organoaxial volvulus (OAV) and mesenteroaxial volvulus (MAV). OAV occurs when the stomach rotates along its longitudinal axis, with the antrum rotating anterosuperior and the fundus rotating posteroinferior. OAV accounts for roughly 2/3 of cases. MAV occurs when the stomach rotates along its short axis, with the antrum displacing above the level of the gastroesophageal junction. A given gastric volvulus may be purely OAV, purely MAV, or a complex case, with components of both OAV and MAV.
Gastric volvulus can be seen in pediatrics and adults, but tends to be more common in the elderly and is associated with Type 3 or 4 parasophageal hernia. OAV is more common in adults. MAV is more common in children, and is frequently associated with an underlying anatomic defect.
Gastric volvulus has a varied presentation, ranging from asymptomatic to acute abdomen. Asymptomatic cases may be found incidentally at time of imaging, and these patients have no gastric outlet obstruction or vascular compromise. When prompted, these patients often elicit a history of GERD. Acute volvulus is a surgical emergency. The classic clinical "Borchardt Triad" consists of violent retching with little vomitus, constant severe epigastric pain, and difficulty advancing an NG tube beyond the distal esophagus. Lastly, chronic/intermittent gastric volvulus is an easily missed diagnosis, due to its vague, nonspecific symptoms and propensity for serendipitous reduction with NG tube placement.
Most adult cases of gastric volvulus result from laxity of stabilizing ligaments, including post-traumatic etiologies. Other cases result from congenital Morgagni hernias, and true idiopathic cases have been observed. Associated pathology includes large parasophageal hernias (allowing all or part of the stomach to enter the chest), diaphragmatic eventration, diaphragmatic paralysis, and wandering spleen (owing to an absence of stabilizing ligaments).
In terms of natural history, an enlarging parasophageal hernia results in an intrathoracic stomach, which is prone to volvulus. Obstruction occurs at points of torsion, and up to 180 degrees of rotation can occur without resulting in obstruction or strangulation. Twisting beyond 180 degrees usually results in an "acute abdomen". OAV is more prone to exceed 180 degrees of twist, making it more likely to obstruct. A so-called "upside-down" stomach can occur with OAV, with or without obstruction, and often presents with GI bleeding and anemia. In cases of strangulation, vascular compromise leads to necrosis, perforation, mediastinitis, peritonitis, and systemic shock. Intramural emphysema and frank perforation are ominous complications, and mortality is reported as high as 30% if obstruction is present.
Early diagnosis is critical to patient outcome, as rapid laparoscopic detorsion may be warranted. Percutaneous endoscopic gastropexy is not uncommonly employed, and gastric resection is required for cases of strangulation and necrosis. Balloon repositioning of the stomach may be attempted in cases of upside-down stomach, and fixation with percutaneous endoscopic gastrostomy is complimentary.
Radiologic overview of the diagnosis:
In terms of radiologic evaluation, radiographs are often the first line modality encountered. Upright abdominal radiographs may show a double air-fluid level with a large, distended stomach or an air and fluid-filled spheric viscus displaced upward and to the left. Collapsed small bowel is worrisome for obstruction. On chest radiographs, an upside-down stomach or retrocardiac fluid level may be seen. Two air-fluid levels at different heights suggest intrathoracic gastric volvulus.
The most optimal modality for evaluation of gastric volvulus remains fluoroscopy, which may demonstrate a massively distended stomach in the left upper quadrant extending into the chest, or inverted stomach contours (greater curvature above the less curvature, cardia and pylorus positioned at the same height, or downward pointing of the pylorus and duodenum). OAV may show 2 discrete twist points with luminal obstruction, and if contrast fails to enter the stomach, the obstruction is presumably at the gastroesophageal junction or proximal stomach. MAV will show the antrum and pylorus to lie above the level of the fundus. Incomplete or absent entrance of contrast into or out of the stomach is compatible with an acute obstructive gastric volvulus.
Gastric volvulus demonstrates a variable appearance on CT, depending on the degree of herniation, points of torsion, and positioning of the stomach. A linear septum within the gastric lumen may or may not be seen, indicating the point of torsion. CT remains valuable for preoperative planning and to assess for underlying malformation, malposition, or diaphragmatic defect.
MRI plays a limited role in imaging gastric volvulus, with coronal sequences demonstrating value in assessing for points of torsion, characterized by different signal intensities.
Angiography can play a diagnostic and therapeutic role if there is concomitant GI bleed.
In terms of initial imaging recommendations, fluoroscopic upper GI series is the first-line modality of choice, with CT playing a complimentary role for anatomic evaluation.