Varices, oesophageal

The anatomical substrate for gastro-oesophageal varices is provided by the anastomoses between the coronary vein and the short gastric veins with the oesophageal and perioesophageal veins and with the splenic vein. The distal perioesophageal plexus anastomoses superiorly with the azygos and hemiazygos system. Distinction is usually made between "uphill" and "downhill" varices.

"Uphill" varices are secondary to reversal of flow in the coronary vein caused by the portal hypertension. Via the azygos vein, which drains into the superior vena cava (SVC) the blood returning from the visceral circulation bypasses the obstructed portal system. Although in many instances associated oesophageal and gastric varices are demonstrated, in some patients only oesophageal varices can be present which is assumed to be due to a better developed connective tissue network supporting the venous channels of the stomach which makes them more resistant to elevated portal pressure.

"Downhill" oesophageal varices are due to obstruction or occlusion of the SVC. Venous circulation draining the upper and middle thirds of the thoracic oesophagus anastomoses with the supreme intercostal vein and other venous channels of the neck and the mediastinum that normally drain into the SVC. If the obstruction is located cranial to the entry of the azygos vein into the SVC, the varices will be limited to the upper and middle thirds of the thoracic oesophagus. However, if the obstruction is located more caudally, flow reversal in the azygos-hemiazygos system will occur. Varices may then be seen involving not only the upper two-thirds of the oesophagus, but also its lower third. Isolated gastric varices are commonly due to splenic vein obstruction. Venous return from the spleen is then diverted through the short gastric veins and the fundal plexus allowing blood to drain into the portal vein via the coronary vein.

Whereas "downhill" varices will only exceptionally cause gastrointestinal blood loss, "uphill" varices frequently lead to bleeding, which may be massive and life threatening. Oesophageal varices can be demonstrated well by barium study including maneouvres designed to increase variceal distension such as Valsalva manoeuvre, Muller manoeuvre and the Trendelenburg position.

Typical radiographic appearance on mucosal relief views is serpiginous thickening of longitudinal folds producing tortuous longitudinal filling defects (Fig.1). Mucosal barium coating of the contracted oesophagus is particularly helpful in demonstrating varices. The changeable nature of varices during fluoroscopy caused by peristalsis, respiration and varying degrees of oesophageal distension, is very useful to differentiate them from other causes of oesophageal fold thickening.

The radiographic features of "downhill" varices is similar to that of "uphill" varices but they are characteristically located in the upper and middle third of the thoracic oesophagus because of the underlying venous anatomy whereas "uphill" varices are most prominent in the distal third of the thoracic oesophagus.

Gastric varices are usually associated with oesophageal varices but are detected radiologically in less than 50% of patients with oesophageal varices on barium study. Their combined presence strongly suggests portal hypertension.

Radiologically gastric varices are apparent as thickened tortuous folds or multiple lobulated filling defects (Fig.2) projecting between curvilinear, crescentic collections of barium in the fundal region. They can be displayed with single contrast technique if small amounts of barium are used or by double contrast techniques. As in the oesophagus, th tend to be located deeper in the submucosa, are routinely displayed in the water-filled stomach as multiple hypoechoic rounded, clustered structures.

Angiography, which has been used extensively in the past for visualization of varices during the venous phase of coeliac and mesenteric angiography or following direct splenoportography, has now been largely abandoned in favour of CT and recently of MR angiography.

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