| Abbreviation | Meaning |
|---|
| 131I or I131 | iodine-131 (aka radioactive iodine or radioiodine) |
| IA | intra-arterial intra-articular |
| IAA | insulin autoantibody |
| IABP | intra-aortic balloon pump |
| IAI | intra-amniotic infection |
| IBC | inflammatory breast cancer |
| IBD | inflammatory bowel disease |
| IBS | irritable bowel syndrome |
| IC | ileocecal
immunocompromised
informed consent
intensive care
interstitial cystitis
immune complex
intracardiac |
| ICC | immunocytochemistry |
| ICD | implantable cardioverter-defibrillator
intercostal drain |
| ICDS | Integrated Child Development Services Program |
| ICD-10 | International Classification of Diseases, 10th Revision |
| ICF | intracellular fluid |
| ICG | impedance cardiography |
| ICH | intracerebral hemorrhage |
| ICI | intracervical insemination |
| ICM | ischemic cardiomyopathy |
| ICP | intracranial pressure |
| ICS | intercostal space
inhaled corticosteroids
internal carotid stenosis |
| ICSI | intracytoplasmic sperm injection |
| ICCU | intensive cardiac care unit |
| ICU | intensive care unit |
| ID | infectious dose
infectious disease
identifying data
intellectual disability |
| I&D | incision and drainage (how to treat an abscess) |
| IDA | iron deficiency anemia |
| IDC | idiopathic dilated cardiomyopathy
indwelling catheter
infiltrating ductal carcinoma |
| IDDM | insulin-dependent diabetes mellitus (now called diabetes mellitus type 1) |
| IDL | intermediate-density lipoprotein |
| IDP | infectious disease precautions |
| IE | infective endocarditis |
| IF | immunofluorescence |
| IFG | impaired fasting glycaemia |
| Ig | immunoglobulin |
| IgA | immunoglobulin A |
| IgAV | IgA vasculitis (formerly known as Henoch–Schönlein purpura) |
| IgD | immunoglobulin D |
| IgE | immunoglobulin E |
| IGF | insulin-like growth factor |
| IgG | immunoglobulin G |
| IgG4-RD | IgG4-related disease |
| IgG4-RKD | IgG4-related kidney disease |
| IgG4-ROD | IgG4-related ophthalmic disease |
| IgG4-TIN | IgG4-related tubulointerstitial nephritis |
| IgM | immunoglobulin M |
| IGT | impaired glucose tolerance |
| IHC | immunohistochemistry |
| IHD | ischaemic heart disease |
| IHPS | infantile hypertrophic pyloric stenosis |
| IHSS | idiopathic hypertrophic subaortic stenosis (hypertrophic cardiomyopathy) |
| II | intellectual impairment |
| IIEF | International Index of Erectile Function |
| ILD | interstitial lung disease |
| ILI | Influenza-like illness |
| IM | intramuscular |
| IMA | inferior mesenteric artery |
| IMB | intermenstrual bleed (bleeding between periods) |
| IMI | intramuscular injection |
| IMM | intramyometrial |
| IMN | infectious mononucleosis
intramedullary nail |
| IMRT | intensity-modulated radiotherapy |
| IMT | inflammatory myofibroblastic tumor
intima-media thickness |
| IMV | intermittent mandatory ventilation (see mechanical ventilation) |
| Inc | incomplete |
| INF(-α/-β/-γ) | interferons -α/-β/-γ |
| INFX | infection |
| INH | inhaled Isoniazid |
| Inj | injection |
| INR | international normalized ratio |
| Int | internal |
| INT | intermittent needle therapy |
| IO | intraosseous infusion |
| I&O | inputs and outputs
intake and outputs |
| IODM | infant of diabetic mother |
| IOL | induction of labor
intraocular lens |
| IOP | intra-occular pressure |
| IP | interphalangeal joint |
| iPSCs | induced pluripotent stem cells |
| IPF | idiopathic pulmonary fibrosis |
| IPG | Implantable Pulse Generator |
| IPH | intraparenchymal hemorrhage or intraperitoneal hemorrhage or idiopathic pulmonary hemosiderosis |
| IPMN | Intraductal papillary mucinous neoplasm |
| IPPB | intermittent positive pressure breathing (see mechanical ventilation) |
| IPPV | intermittent positive pressure ventilation (see mechanical ventilation) |
| IPS | intraperitoneal sounds |
| IQ | intelligence quotient |
| IR | insulin resistance
Interventional radiology |
| IRDS | infant respiratory distress syndrome |
| IRIDA | inherited iron-refractory iron deficiency anemia |
| IRIS | Immune reconstitution inflammatory syndrome |
| IS | Incentive Spirometry |
| ISA | intrinsic sympathomimetic activity |
| ISDN | isosorbide dinitrate |
| ISH | isolated systolic hypertension |
| ISMN | isosorbide mononitrate |
| ISQ | no change (from Latin, in status quo) |
| IT | immature teratoma
intrathecal |
| ITP | idiopathic thrombocytopenic purpura
immune-mediated thrombocytopenic purpura |
| ITU | intensive treatment unit (or intensive therapy unit) |
| IUCD | intrauterine contraceptive device |
| IU | international units |
| IUD | intrauterine death—sometimes confused with intrauterine contraceptive device—use FDIU or IUFD instead.
intrauterine device—sometimes confused with intrauterine death—use IUCD instead (intrauterine contraceptive device) |
| IUFD | intrauterine foetal demise |
| IUGR | intrauterine growth restriction |
| IUI | intrauterine insemination |
| IUP | intrauterine pregnancy |
| IUPC | intrauterine pressure catheter |
| IUS | intrauterine system |
| IUT | intrauterine transfusion |
| IV | intravenous |
| IVC | inferior vena cava |
| IVD | Intervertebral disc |
| IV-DSA | intravenous digital subtraction angiography |
| IVDU | intravenous drug user |
| IVF | in vitro fertilization;
intravenous fluids |
| IVH | interventricular hemorrhage |
| IVIG | intravenous immunoglobulin |
| IVP | intravenous pyelogram |
| IVPB | intravenous piggyback (i.v. short-term infusion) |
| IVPG | Intravenous pyogenic granuloma |
| IVSS | Intravenous Soluset [1] |
| IVU | intravenous urogram |
| IVUS | intravascular ultrasound |
| Ix | Investigation(s) |