| Abbreviations | Meaning |
 | UGI | (see GI) Upper Gastrointestinal |
 | OG | Obstetrics And Gynecology; Occlusogingival; 1-O-octyl-beta-D-glucopyranoside; Oligodendrocyte; Optic Ganglion; Orange Green; Orogastric; [protective] Overgarment |
 | NBM | No Bowel Movement; Normal Bone Marrow; Normal Bowel Movement; Nothing By Mouth |
 | GCA | Gastric Cancer Area; Giant Cell Arteritis |
 | LGI | (see GI) Lower Gastro-intestinal Tract |
 | IO | Intestinal Obstruction |
 | PGS | Postsurgical Gastroparesis Syndrome |
 | SIM | Specialized Intestinal Metaplasia |
 | GIF | Gastric Intrinsic Factor; Gonadotropin-inhibiting Factor; Graphic Interchange Format [imaging]; Growth Hormone-inhibiting Factor |
 | SBS | Short Bowel Syndrome |
 | CRIP | Cysteine-rich Intestinal Protein |
 | N-CAP | Nifedipine Gastrointestinal Therapeutic System Circadian Anti-Ischemic Program |
 | GES | Gastroesophageal Sphincter; Glucose-electrolyte Solution |
 | GTB | Gastrointestinal Tract Bleeding |
 | WBI | Web-based Instruction [telemedicine]; Whole Bowel Irrigation |