The main complications of gastric ulcers are fourfold: one is upper gastrointestinal bleeding; the second is perforation; the third is pyloric obstruction; the fourth is malignant transformation.

Upper gastrointestinal bleeding is the most common complication of gastric ulcers. If a patient has experienced bleeding, there is a high likelihood of recurrence. Perforations mainly occur in elderly individuals. Pyloric obstruction is primarily caused by ulcers in the pyloric canal and pre-pyloric area. It is divided into mechanical obstruction and functional obstruction. Mechanical obstruction results from scarring after the ulcer heals, which narrows the pyloric opening. Functional obstruction is due to congestion and edema of the mucosa after the ulcer, causing relative narrowing of the pylorus. As for malignant transformation, it is still controversial, but it is generally believed to be around 1%-7%.