L1: In the last part of the small intestine (terminal ileum) – 20-27%
L2: In the large intestine – 23-48%
L3: In both small intestine and large intestine – 23-43%
L4: Upper digestive tract (esophagus, stomach, duodenum) – 2%
Solberg et al. In their study in Norway, it was determined that 27% of Crohn’s patients were in the L1, 48% in the L2 group, 23% in the L3 and 2% in the L2 group. Jess et al. In the study they carried out in Denmark, the rate of patients in the L2 group was found to be between 30-43%.
Lakatos et al. In the study they carried out in Hungary, the L1 group was determined as 20%, the L2 group 35%, the L3 group 43% and the L4 group 2%. Ng et al. They found similar results in their studies in Asia and Australia.
According to the way of movement
B1: No stenosis or perforation (68-81%)
B2: There is stenosis (5%)
B3: Perforation present (14%)
Thia et al. In their study at the Mayo Clinic, they determined that 81% of Crohn’s disease cases were group B1, 5% group B2, and 14% group B3. In the ECCO-EpiCom study carried out in Europe, it was determined that 68-75% of the patients were in the B1 group and 10% had disease in the breech region.