Peptic ulcers occur most commonly in the first part of the duodenum where it is known as a duodenal ulcer. They are also common along the curvature of the stomach and are called gastric ulcers. They may occur in other sites but duodenal and gastric ulcers are by far the most common. | Peptic ulcers occur most commonly in the first part of the duodenum where it is known as a duodenal ulcer. They are also common along the curvature of the stomach and are called gastric ulcers. They may occur in other sites but duodenal and gastric ulcers are by far the most common. |