Intestinal metaplasia (IM) occurs when cells in the tissues of the upper digestive tract, often in the stomach or esophagus, change and become more like cells from the intestines. Intestinal metaplasia in the esophagus is also called Barrett’s esophagus. Intestinal metaplasia is more common in people who have chronic acid reflux or gastroesophageal reflux disease (GERD). The exact cause of intestinal metaplasia is still uncertain. Some healthcare professionals believe an H. pylori infection causes intestinal metaplasia, but there is also a range of risk factors that may increase the risk of developing it. While it is not possible to avoid some risk factors such as genetics, people can avoid other risk factors, including diet, H. pylori infection, and smoking.
Intestinal metaplasia can be severe. The transformation of the cells of the gastric lining puts a person at a much higher risk of developing gastric cancer. It is believed the risk for progression into gastric cancer is highest among patients with diffuse gastric IM (which involves both antrum and body). Once dysplasia is present, the location is less important as there is a higher risk regardless of location. The median time until diagnosis of cancer among the patients with GIM was 4.6 years.
Currently, there is no ICD-10-CM unique code for gastric IM. The October 2021 updates will include 10 new codes in two new subcategories for gastric intestinal metaplasia, one without dysplasia (Table 1) and one with dysplasia (Table 2).
| CODE | DESCRIPTION |
| K31.A0 | Gastric intestinal metaplasia, unspecified |
| K31.A11 | Gastric intestinal metaplasia without dysplasia, involving the antrum |
| K31.A12 | Gastric intestinal metaplasia without dysplasia, involving the body (corpus) |
| K31.A13 | Gastric intestinal metaplasia without dysplasia, involving the fundus |
| K31.A14 | Gastric intestinal metaplasia without dysplasia, involving the cardia |
| K31.A15 | Gastric intestinal metaplasia without dysplasia, involving multiple sites |
| K31.A19 | Gastric intestinal metaplasia without dysplasia, unspecified site |
| CODE | DESCRIPTION |
| K31.A21 | Gastric intestinal metaplasia with low grade dysplasia |
| K31.A22 | Gastric intestinal metaplasia with high grade dysplasia |
| K31.A29 | Gastric intestinal metaplasia with dysplasia unspecified |