Diseases of Stomach and Duodenum ICD 9 Codes (531-5. Appendicitis ICD 9 Codes (540-543) Hernia of Abdominal Cavity ICD 9 Codes (550-553). Icd9 Code For Diffuse Gastric Wall Thickening - posted: 12 December 2013 2.46 - The following information about icd9 code for diffuse gastric wall thickening and the.