The x-ray features of the lower esophageal web differ from both the middle esophageal web and the lower esophageal ring. The proximal end of the web (cephalic end) shows symmetrical expansion of the esophagus and the distal end (esophageal vestibular area) shows a double concave surface. It is one of the clinical manifestations of esophageal webs and rings. What causes esophageal webbing and annulus esophagus? Esophageal webs may be caused by the formation of vacuoles during the development of the esophagus during the embryonic period, which fuse incompletely and leave a partial or complete mucosal annular diaphragm; it is also thought to be caused by the overgrowth of squamous epithelium that replaces the villous columnar cells during the development of the esophagus. The esophageal muscle ring is caused by overgrowth of the mesodermal component during the formation of the esophageal muscle layer in the embryonic period, resulting in esophageal stricture. Patients with upper esophageal webbing are usually asymptomatic when eating a liquid diet, but mostly appear when eating hard foods, mainly manifesting as intermittent dysphagia and a feeling of food retention in the upper chest. Most patients with middle esophageal webbing are asymptomatic, but congenital middle esophageal webbing should be considered in infants over 5 to 11 months of age with intermittent vomiting or sudden esophageal obstruction. In adults, the cause of mid-oesophageal webbing is unknown. It presents with intermittent difficulty swallowing harder foods and a sensation of food stagnation behind the sternum. The clinical features of lower esophageal webbing are similar to those of lower esophageal rings. Intermittent dysphagia is the main symptom of lower esophageal ring. When eating in a hurry, the patient has the sensation that the food mass is blocking the esophagus and cannot be swallowed. The patient tries to relieve the symptoms by spitting out the food or drinking water to wash down the food mass. If this works, the patient will learn a lesson from it and chew slowly during the next meal to avoid the suffering of difficulty in swallowing due to the rush to eat, and will not have similar symptoms for weeks or even months. The lower esophageal ring prevents acid reflux, and the patient does not have heartburn. However, after repeated dilatation treatment, although the dysphagia disappears, the anti-reflux barrier is destroyed, and reflux esophagitis may develop. Patients with lower esophageal rings have sliding esophageal hiatal hernia, which can also present with reflux symptoms. Esophageal obstruction is one of the complications, which can lead to spontaneous esophageal rupture if it is repeated and causes esophageal dilatation.