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Medical Abbreviations Starting With "I"
This page lists 272 medical abbreviations starting with "I", each with its full form and a plain-English meaning. Where one abbreviation has more than one common meaning, each meaning has its own row — context in the chart is what tells them apart. Terms flagged ⚠ Error-prone are on recognised error-prone lists and should be written out in full. Use the filter box to narrow this list, the search on the main guide to search all 5,715 entries, or jump to another letter:
A B C D E F G H J K L M N 0–9 O P Q R S T U V W X Y Z
| Abbreviation | Full form | What it means | Used in |
|---|---|---|---|
| I&D | incision and drainage | Cutting open and draining a collection of pus | Surgery |
| I&O | intake and output | Measurement of fluids taken in and passed out | Nursing Renal & Nephrology |
| I&O cath | in-and-out catheterization | One-time straight catheter drainage | Nursing Renal & Nephrology |
| I&O strict | strict intake and output | Precise measurement of all fluids in and out | Nursing Renal & Nephrology |
| I-131 | iodine-131 | Radioactive iodine treating thyroid disease and cancer | Endocrinology Radiology & Imaging Prescription & Medication Orders |
| I-PASS | I-PASS handoff bundle | Standardized handoff mnemonic and bundle | Nursing General Medical Pediatrics |
| I:E | inspiratory-to-expiratory ratio (setting) | Breathing-in versus breathing-out time ratio | Respiratory Emergency & Critical Care |
| IA-2 | islet antigen-2 | Pancreatic islet target of antibodies in type 1 diabetes | Laboratory Endocrinology |
| IAA | insulin autoantibody | Antibody against insulin seen in early type 1 diabetes | Laboratory Endocrinology |
| IAB | induced abortion (term) | Intentional ending of pregnancy | Obstetrics & Gynecology |
| IABP | intra-aortic balloon pump | Balloon device in the aorta that supports heart pumping | Cardiology Emergency & Critical Care |
| IAD | illness anxiety disorder | Excessive worry about having a serious illness | Psychiatry |
| IAD | incontinence-associated dermatitis | Skin injury from urine or stool exposure | Nursing |
| IADL | instrumental activities of daily living | Complex daily tasks such as shopping and managing money | General Medical Nursing |
| IAI | intraamniotic infection | Infection inside the womb during pregnancy | Obstetrics & Gynecology Infectious Disease |
| IAT | indirect antiglobulin test | Test detecting red cell antibodies in plasma | Laboratory Hematology & Oncology |
| IBCLC | International Board Certified Lactation Consultant | Lactation specialist credential | Pediatrics Obstetrics & Gynecology Nursing |
| IBD | inflammatory bowel disease | Long-term gut inflammation, mainly Crohn's and ulcerative colitis | Gastroenterology |
| IBD child | pediatric inflammatory bowel disease (term) | Childhood Crohn and colitis grouping | Pediatrics Gastroenterology |
| IBM | inclusion body myositis | Slowly progressive muscle disease mainly in older adults | Musculoskeletal Neurology |
| IBRU | ibrutinib (chart shorthand) | BTK blocker pill shorthand | Prescription & Medication Orders Hematology & Oncology |
| IBS | irritable bowel syndrome | Gut condition with pain, bloating and changed bowel habit | Gastroenterology |
| IBS child | childhood irritable bowel syndrome () | Functional bowel pain pattern — childhood | Pediatrics Gastroenterology |
| IC | inspiratory capacity | Maximum air that can be breathed in after a normal breath out | Respiratory |
| IC anatomy | internal capsule (anatomy) | White matter highway in the deep brain | Neurology |
| ICA | internal carotid artery | Neck artery supplying most of the brain | Cardiology |
| ICA | islet cell antibody | Pancreatic islet antibody in autoimmune diabetes | Laboratory Endocrinology |
| ICA anatomy | internal carotid artery (anatomy) | Neck artery to the brain — anatomy | Neurology General Medical |
| iCa CRRT | ionized calcium (citrate monitoring) | Calcium checks guiding citrate therapy | Renal & Nephrology Emergency & Critical Care Laboratory |
| ICARS | International Cooperative Ataxia Rating Scale | Detailed ataxia rating scale | Neurology |
| ICCE | intracapsular cataract extraction | Historical whole-lens cataract removal | General Medical Surgery |
| ICD | implantable cardioverter-defibrillator | Implanted device that shocks the heart out of dangerous rhythms | Cardiology |
| ICD | intercostal drain | Tube between the ribs draining the chest | Surgery Respiratory |
| ICD | International Classification of Diseases | Global system coding diagnoses | General Medical |
| ICD device | implantable cardioverter-defibrillator (device) | Implanted shocking device — device | Cardiology |
| ICD-10 | International Classification of Diseases, 10th Revision | Diagnosis coding system, tenth revision | General Medical |
| ICDSC | Intensive Care Delirium Screening Checklist | ICU delirium checklist | Emergency & Critical Care Neurology |
| ICE | ifosfamide carboplatin etoposide | Salvage lymphoma chemotherapy combination | Hematology & Oncology Prescription & Medication Orders |
| ICE | intracardiac echocardiography | Ultrasound imaging from inside the heart | Radiology & Imaging Cardiology |
| ice test | ice pack test (myasthenia) | Cold improving a droopy lid in myasthenia | Neurology |
| ICGA | indocyanine green angiography | Dye imaging of choroidal circulation | General Medical Radiology & Imaging |
| ICH | intracerebral hemorrhage | Bleeding inside the brain tissue itself | Neurology Emergency & Critical Care |
| ICH score | ICH score (prognosis) | Brain bleed outcome score — prognosis | Neurology Emergency & Critical Care |
| ICHD | International Classification of Headache Disorders | Standard headache diagnosis framework | Neurology |
| ICI | immune checkpoint inhibitor | Immunotherapy class releasing brakes on immune cells | Prescription & Medication Orders Hematology & Oncology |
| ICL | implantable collamer lens | Implanted lens for vision correction | General Medical Surgery |
| icodextrin | icodextrin (PD fluid) | Long-dwell glucose-polymer PD fluid | Renal & Nephrology Prescription & Medication Orders |
| ICP | intracranial pressure | Pressure inside the skull | Neurology Emergency & Critical Care |
| ICP | intrahepatic cholestasis of pregnancy (itching) | Liver bile problem causing itching — pregnancy | Obstetrics & Gynecology Gastroenterology |
| ICS | inhaled corticosteroid (maintenance) | Daily inhaled steroid — maintenance | Pediatrics Respiratory Prescription & Medication Orders |
| ICSI | intracytoplasmic sperm injection | Injecting one sperm into an egg | Obstetrics & Gynecology |
| ICT | immunochromatographic test | Rapid strip test using colored particles | Laboratory General Medical |
| ICU | intensive care unit | Unit for critically ill patients needing close monitoring | Emergency & Critical Care |
| ID | infectious disease | Illness caused by germs, or the specialty treating them | Infectious Disease |
| ID | intellectual disability | Condition with limited intellectual and adaptive functioning from development | Psychiatry Pediatrics |
| IDA | idarubicin (chart shorthand) | Anthracycline leukemia drug shorthand | Prescription & Medication Orders Hematology & Oncology |
| IDA child | iron deficiency anemia (childhood) | Low iron anemia of childhood | Pediatrics Laboratory Hematology & Oncology |
| IDDSI | International Dysphagia Diet Standardisation Initiative | Global framework for food and drink texture levels | Nursing Neurology General Medical |
| IDerm | intradermal | Into the skin, describing an injection route | Prescription & Medication Orders Nursing |
| IDWG | interdialytic weight gain | Fluid weight gained between dialysis sessions | Renal & Nephrology Nursing |
| IE | ifosfamide etoposide | Sarcoma chemotherapy combination shorthand | Hematology & Oncology Prescription & Medication Orders |
| IE | infective endocarditis | Infection of the inner lining or valves of the heart | Cardiology |
| IED | intermittent explosive disorder | Repeated impulsive aggressive outbursts out of proportion | Psychiatry |
| IEP | individualized education program | School plan setting out special education support for a child | Pediatrics |
| IES-R | Impact of Event Scale Revised | Post-traumatic stress symptom scale | Psychiatry |
| IFA | indirect fluorescent antibody | Microscopy antibody test method | Laboratory General Medical |
| IFALD | intestinal failure-associated liver disease | Liver injury from long-term IV nutrition | Pediatrics Gastroenterology |
| IFE | immunofixation electrophoresis | Lab test identifying abnormal antibody proteins | Laboratory Hematology & Oncology |
| IFG | impaired fasting glucose | Fasting blood sugar higher than normal but not diabetes | Endocrinology Laboratory |
| IFO | ifosfamide (chart shorthand) | Alkylating chemotherapy shorthand | Prescription & Medication Orders Hematology & Oncology |
| IFSP | individualized family service plan | Early intervention plan for infants and toddlers with delays | Pediatrics |
| IFTA | interstitial fibrosis and tubular atrophy (graft) | Scarring pattern in transplant biopsies | Renal & Nephrology Laboratory |
| IgA | immunoglobulin A | Antibody protecting mucosal surfaces like the gut | Laboratory Infectious Disease Gastroenterology |
| IgAN | IgA nephropathy | Kidney disease from IgA deposits in the filters | Renal & Nephrology |
| IgAN child | IgA nephropathy (childhood) | Kidney disease with visible blood after colds — childhood | Pediatrics Renal & Nephrology |
| IgAV | IgA vasculitis (current term) | Current name for Henoch-Schönlein purpura | Pediatrics Renal & Nephrology |
| IgE | immunoglobulin E | Antibody involved in allergy | Laboratory Infectious Disease Respiratory |
| IGF tx | immediate graft function (transplant) | Promptly working transplant kidney | Renal & Nephrology Surgery |
| IGF-1 | insulin-like growth factor 1 | Hormone reflecting growth hormone activity | Laboratory Endocrinology |
| IGFBP-1 test | insulin-like growth factor binding protein-1 test | Ruptured membrane test protein | Obstetrics & Gynecology Laboratory |
| IGFBP-3 | insulin-like growth factor binding protein 3 | Carrier protein used in growth assessment | Laboratory Endocrinology Pediatrics |
| IgG | immunoglobulin G | Most common antibody type in blood | Laboratory Infectious Disease |
| IgG index | immunoglobulin G index (CSF) | Ratio supporting MS diagnosis | Neurology Laboratory |
| IgM | immunoglobulin M | First antibody type made in a new infection | Laboratory Infectious Disease |
| IgM anti-HAV | IgM hepatitis A antibody | Marker of acute hepatitis A | Laboratory Infectious Disease |
| IgM anti-HBc | IgM hepatitis B core antibody | Marker of recent hepatitis B infection | Laboratory Infectious Disease |
| IGRA | interferon-gamma release assay | Blood test for tuberculosis infection | Respiratory Laboratory Infectious Disease |
| IGRA child | interferon-gamma release assay (childhood) | TB blood test — childhood | Pediatrics Infectious Disease Laboratory |
| IGRT | image-guided radiation therapy | Daily imaging used to aim radiation precisely | Hematology & Oncology Radiology & Imaging |
| IGT | impaired glucose tolerance | Blood sugar higher than normal but not diabetes | Endocrinology Laboratory |
| IHC | immunohistochemistry | Lab staining using antibodies on tissue samples | Laboratory Hematology & Oncology |
| IHCA | in-hospital cardiac arrest | Cardiac arrest occurring inside a hospital | Cardiology Emergency & Critical Care |
| IHD | intermittent hemodialysis (session) | Standard discrete dialysis sessions | Renal & Nephrology Emergency & Critical Care |
| IHD | ischemic heart disease | Heart disease caused by reduced blood supply to heart muscle | Cardiology |
| IIA | internal iliac artery | Pelvic artery feeding the pelvic organs | Obstetrics & Gynecology Radiology & Imaging |
| IIH | idiopathic intracranial hypertension | Raised pressure in the skull without a found cause | Neurology |
| IIH eye | idiopathic intracranial hypertension (eye findings) | Raised brain pressure threatening vision | Neurology General Medical |
| IJV | internal jugular vein | Large neck vein used for central access | Emergency & Critical Care |
| IKDC | International Knee Documentation Committee score | Knee evaluation form | Musculoskeletal |
| ILAE | International League Against Epilepsy | Body classifying seizures and epilepsies | Neurology General Medical |
| ILD | interstitial lung disease | Group of diseases causing scarring or inflammation of lung tissue | Respiratory |
| ileal conduit | ileal conduit (urinary diversion) | Bowel segment channeling urine to a stoma | Surgery Renal & Nephrology |
| ileocecal | ileocecal valve (anatomy) | Valve between small bowel and colon | Gastroenterology |
| iliac art | common iliac artery | Main pelvic artery | General Medical Radiology & Imaging |
| ilioinguinal n | ilioinguinal nerve | Groin skin nerve at risk in hernia surgery | Neurology Surgery |
| illness anxiety | illness anxiety disorder (diagnosis) | Health worry with few symptoms — diagnosis | Psychiatry |
| ILM peel | internal limiting membrane peel | Removing the retina's innermost layer in macular surgery | Surgery |
| ILR | implantable loop recorder (device) | Under-skin long-term rhythm recorder | Cardiology |
| IM | intramuscular | Into a muscle, describing an injection route | Prescription & Medication Orders Nursing |
| IM nail | intramedullary nail | Metal rod placed inside a bone to fix a fracture | Musculoskeletal Surgery |
| IM nail | intramedullary nailing (procedure) | Rod fixation inside a long bone | Surgery Musculoskeletal |
| IMA | inferior mesenteric artery | Artery feeding the lower colon | Gastroenterology Radiology & Imaging |
| IMAT | imatinib (chart shorthand) | BCR-ABL blocker pill that transformed CML care | Prescription & Medication Orders Hematology & Oncology |
| IMB | intermenstrual bleeding | Vaginal bleeding between periods | Obstetrics & Gynecology |
| IMC | intermediate care unit | Step-down level care | Nursing Emergency & Critical Care |
| IMCU | intermediate care unit (full abbreviation) | Step-down care unit | Nursing Emergency & Critical Care |
| immunization catch-up | catch-up immunization (schedule) | Making up missed vaccines — schedule | Pediatrics Infectious Disease |
| immunization SIDS | immunization (no SIDS link) | Vaccination not linked to sleep deaths — counseling | Pediatrics Infectious Disease Nursing |
| immunoadsorption | immunoadsorption (antibody column) | Column removing antibodies from blood | Renal & Nephrology Laboratory Surgery |
| ImPACT | ImPACT (computerized concussion test) | Computer concussion battery brand | Pediatrics Neurology |
| imperforate anus | anorectal malformation (diagnosis) | Absent or misplaced anus — diagnosis | Pediatrics Surgery |
| impetigo | impetigo (diagnosis) | Honey-crusted skin infection — diagnosis | Pediatrics Infectious Disease |
| implant recon | implant-based breast reconstruction | Rebuilding the breast with an implant | Surgery |
| IMPROVE | IMPROVE VTE risk score | Hospital patient clot risk model | Hematology & Oncology |
| IMRT | intensity-modulated radiation therapy | Shaped radiation sparing nearby tissue | Hematology & Oncology Radiology & Imaging |
| IMV | intermittent mandatory ventilation (mode) | Set breaths between spontaneous ones, older mode | Respiratory Emergency & Critical Care |
| in-toeing | in-toeing (gait variant) | Toes pointing inward when walking | Pediatrics Musculoskeletal |
| inattentive ADHD | predominantly inattentive presentation (ADHD) | Attention-type ADHD pattern | Pediatrics Psychiatry |
| incident report | incident report (occurrence report) | Safety event documentation | Nursing General Medical |
| incisional biopsy | incisional biopsy (procedure) | Sampling part of a lesion | Surgery General Medical |
| inclined sleeper | inclined sleepers (recalled products) | Reclined infant sleep products recalled for deaths | Pediatrics Emergency & Critical Care |
| incomplete AB | incomplete abortion (term) | Part of the pregnancy tissue retained | Obstetrics & Gynecology |
| incomplete Kawasaki | incomplete Kawasaki disease (term) | Kawasaki without the full criteria | Pediatrics Cardiology |
| inconsolable | inconsolable crying (red flag) | Crying not soothed by comfort — warning | Pediatrics Emergency & Critical Care |
| incremental HD | incremental hemodialysis (start strategy) | Starting with fewer sessions and building up | Renal & Nephrology |
| independent advocate | independent living donor advocate (role) | Donor-protecting team member role | Renal & Nephrology Surgery General Medical |
| induction tx | induction therapy (transplant) | Strong early anti-rejection treatment | Renal & Nephrology Prescription & Medication Orders Surgery |
| inevitable AB | inevitable abortion (term) | Miscarriage in progress with open cervix | Obstetrics & Gynecology |
| infant car seat challenge | infant car seat challenge (test) | Seated monitoring test | Pediatrics Nursing |
| infantile hemangioma | infantile hemangioma (diagnosis) | Strawberry birthmark tumor — diagnosis | Pediatrics Surgery |
| infantile spasms | infantile spasms (epilepsy) | Infant seizure type with developmental risk | Neurology Pediatrics |
| Infasurf | Infasurf (calfactant brand) | Calf-derived surfactant brand | Pediatrics Prescription & Medication Orders |
| infiltration access | needle infiltration (access injury) | Needle through the vessel wall causing a hematoma | Renal & Nephrology Nursing |
| ingestion | ingestion (presentation) | Swallowed substance presentation | Emergency & Critical Care Pediatrics |
| inguinal hernia repair | inguinal hernia repair (procedure) | Fixing a groin hernia — procedure | Surgery |
| inguinal lig | inguinal ligament (anatomy) | Groin crease ligament | Surgery General Medical |
| Inh | inhalation | Breathed in, describing a medicine route | Prescription & Medication Orders Respiratory |
| INH | isoniazid | Antibiotic medicine used against tuberculosis | Prescription & Medication Orders Infectious Disease |
| inhaled epi | inhaled epoprostenol (iEPO) | Inhaled lung vessel dilator used in place of nitric oxide | Respiratory Emergency & Critical Care Prescription & Medication Orders |
| inhibin B | inhibin B (ovarian hormone) | Hormone used in fertility and ovarian assessment | Laboratory Obstetrics & Gynecology Endocrinology |
| initial OH | initial orthostatic hypotension | Brief pressure drop immediately on standing | Neurology Cardiology |
| inline suction | closed suction catheter (inline) | Suction without disconnecting the ventilator | Nursing Respiratory Emergency & Critical Care |
| INN | international nonproprietary name | Globally standard name of a medicine substance | Prescription & Medication Orders |
| inner cannula | inner cannula (trach) | Removable inner tube of a tracheostomy | Nursing Respiratory |
| innocent murmur | innocent murmur (term) | Harmless childhood heart sound | Pediatrics Cardiology |
| innominate | brachiocephalic artery (innominate) | First large branch off the aortic arch | General Medical Radiology & Imaging |
| iNO | inhaled nitric oxide (neonatal) | Lung vessel relaxing gas — neonatal | Pediatrics Respiratory Emergency & Critical Care Prescription & Medication Orders |
| INO | internuclear ophthalmoplegia (finding) | Eye movement disconnect from a brainstem lesion — finding | Neurology |
| iNO adult | inhaled nitric oxide (adult ARDS) | Lung vessel relaxing gas — adult lung failure | Respiratory Emergency & Critical Care Prescription & Medication Orders |
| inpatient status | inpatient status (admission type) | Full admission status | Nursing General Medical |
| INR | international normalized ratio | Standardised measure of blood clotting tendency | Laboratory Hematology & Oncology |
| insight MSE | insight (mental status element) | Understanding of one's illness | Psychiatry |
| INSTI | integrase strand transfer inhibitor | HIV drug class blocking viral integration | Infectious Disease Prescription & Medication Orders |
| instrument count | instrument count (surgical) | Verifying all instruments before wound closure | Nursing Surgery |
| insula | insular cortex (anatomy) | Deep folded brain region | Neurology |
| insulin drip | insulin infusion (DKA protocol) | Continuous insulin in ketoacidosis care — protocol | Emergency & Critical Care Endocrinology Prescription & Medication Orders Nursing |
| INSURE | intubate surfactant extubate (technique) | Give surfactant then remove the tube quickly | Pediatrics Respiratory |
| intent SI | suicidal intent (assessment element) | Determination to act on suicidal thoughts | Psychiatry |
| intercostals | intercostal muscles (group) | Muscles between the ribs used in breathing | Respiratory Musculoskeletal |
| interdisciplinary rounds | interdisciplinary rounds (IDR) | Multi-team daily patient review | Nursing General Medical |
| INTERGROWTH | INTERGROWTH-21st (standards) | International newborn growth standards project | Pediatrics Obstetrics & Gynecology |
| interhemispheric | interhemispheric subdural (abuse pattern) | Blood along the midline in inflicted injury | Pediatrics Neurology Radiology & Imaging |
| interossei | interosseous muscles (hand) | Muscles between hand bones spreading fingers | Musculoskeletal |
| interrupted arch | interrupted aortic arch (defect) | Gap in the aorta arch | Pediatrics Cardiology Emergency & Critical Care |
| intox | intoxication (documentation shorthand) | Under the influence — documentation shorthand | Psychiatry Emergency & Critical Care |
| Intraop | intraoperative | During an operation | Surgery |
| introducer | introducer sheath (device) | Large-bore access sheath for catheters | Cardiology Emergency & Critical Care Radiology & Imaging |
| intussusception | intussusception (diagnosis) | Telescoping bowel — diagnosis | Pediatrics Gastroenterology Surgery Emergency & Critical Care Radiology & Imaging |
| IO | intestinal obstruction | Blockage of the intestines | Gastroenterology Surgery |
| IO | intraosseous | Into bone marrow, an emergency access route | Emergency & Critical Care Prescription & Medication Orders |
| IO | intraosseous access | Needle into bone marrow for emergency fluids | Emergency & Critical Care |
| IO needle | intraosseous needle (device) | Drill-placed bone access needle | Emergency & Critical Care Nursing |
| IO neonate | intraosseous access (newborn resuscitation) | Bone access in newborn emergencies | Pediatrics Emergency & Critical Care |
| IOL | induction of labor | Starting labour artificially before it begins on its own | Obstetrics & Gynecology |
| IOL | intraocular lens | Artificial lens implanted at cataract surgery | General Medical Surgery |
| IOOA | inferior oblique overaction | Eye muscle overaction pattern in strabismus | General Medical Pediatrics |
| IOP | intraocular pressure | Pressure inside the eye | General Medical Vitals & Assessment |
| IP H | intraparenchymal hemorrhage (term) | Bleeding within brain tissue | Neurology Radiology & Imaging |
| IPC | indwelling pleural catheter | Tunneled long-term chest drain | Respiratory Surgery |
| IPC | intermittent pneumatic compression | Inflating sleeves preventing leg clots | Nursing Surgery |
| IPD | intermittent peritoneal dialysis (in-center) | Periodic facility peritoneal dialysis | Renal & Nephrology |
| IPF | idiopathic pulmonary fibrosis | Progressive lung scarring with no known cause | Respiratory |
| IPF | immature platelet fraction | Young platelet percentage showing platelet production | Laboratory Hematology & Oncology |
| IPI | International Prognostic Index (lymphoma) | Aggressive lymphoma risk score | Hematology & Oncology |
| IPI | ipilimumab (chart shorthand) | CTLA-4 immune checkpoint drug shorthand | Prescription & Medication Orders Hematology & Oncology |
| IPM | imipenem (chart shorthand) | Carbapenem antibiotic chart shorthand | Prescription & Medication Orders Infectious Disease |
| IPP | inflatable penile prosthesis | Pump-operated erection implant | Surgery Renal & Nephrology |
| IPPV | intermittent positive pressure ventilation | Machine-delivered positive pressure breaths | Respiratory Emergency & Critical Care |
| IPS | International Prognostic Score (Hodgkin) | Hodgkin lymphoma risk score | Hematology & Oncology |
| IPSS | International Prognostic Scoring System | MDS and myelofibrosis risk scoring | Hematology & Oncology |
| IPSS | International Prostate Symptom Score | Questionnaire grading prostate urinary symptoms | Renal & Nephrology |
| IPSS-M | molecular International Prognostic Scoring System | Mutation-based MDS risk score | Hematology & Oncology |
| IPSS-R | revised International Prognostic Scoring System | Refined MDS risk score | Hematology & Oncology |
| IPT | interpersonal psychotherapy | Therapy focused on relationships and life events | Psychiatry |
| IPT | interpersonal therapy | Relationship-focused depression therapy | Psychiatry |
| IPV | inactivated poliovirus vaccine | Injected polio vaccine using killed virus | Infectious Disease Pediatrics |
| IQ | intelligence quotient | Standard score comparing thinking ability with peers | Psychiatry |
| IQCODE | Informant Questionnaire on Cognitive Decline | Informant-based cognitive decline screen | Neurology Psychiatry |
| IR | immediate release | Medicine released quickly after taking | Prescription & Medication Orders |
| IR | interventional radiology | Image-guided minimally invasive procedures | Radiology & Imaging |
| IR drain | image-guided drain placement | Radiology placement of a drainage catheter | Radiology & Imaging Surgery |
| IRBC | irradiated red blood cells | Red cells treated to prevent graft-versus-host disease | Hematology & Oncology Laboratory |
| iRECIST | immune RECIST | Response rules adapted for immunotherapy | Hematology & Oncology |
| IRINO | irinotecan (chart shorthand) | Colon cancer chemotherapy shorthand | Prescription & Medication Orders Hematology & Oncology Gastroenterology |
| IRIS | immune reconstitution inflammatory syndrome | Worsening inflammation as immunity recovers after HIV treatment starts | Infectious Disease |
| iron def child | iron deficiency (childhood) | Commonest childhood nutritional deficiency | Pediatrics Laboratory Hematology & Oncology |
| IRT | immunoreactive trypsinogen (CF screen) | Newborn CF screening marker | Pediatrics Laboratory |
| IRV | inspiratory reserve volume | Extra air that can be breathed in after a normal breath in | Respiratory |
| IS | incentive spirometer | Breathing device encouraging deep breaths | Nursing Respiratory |
| IS XM | immediate spin crossmatch | Quick crossmatch for patients without antibodies | Laboratory Hematology & Oncology |
| ISA | isavuconazole (chart shorthand) | Azole antifungal chart shorthand | Prescription & Medication Orders Infectious Disease |
| ischemic monomelic | ischemic monomelic neuropathy (access) | Nerve injury after access creation without obvious steal signs | Renal & Nephrology Neurology Surgery |
| ISDN | isosorbide dinitrate | Nitrate medicine for chest pain and heart failure | Prescription & Medication Orders Cardiology |
| ISI | Insomnia Severity Index | Insomnia questionnaire | Psychiatry Neurology |
| ISMN | isosorbide mononitrate | Long-acting nitrate medicine for chest pain | Prescription & Medication Orders Cardiology |
| ISMP | Institute for Safe Medication Practices | Organization publishing medication safety lists | Prescription & Medication Orders Nursing General Medical |
| Isolation | isolation precautions | Measures separating infectious patients to protect others | Infectious Disease Nursing |
| isolette | isolette (incubator) | Enclosed heated baby bed | Pediatrics Nursing |
| ISS | inferior sagittal sinus | Vein channel along the lower midline brain fold | Neurology |
| ISS | Injury Severity Score | Score grading overall severity of injuries | Emergency & Critical Care Surgery |
| ISS | International Staging System (myeloma) | Myeloma staging from albumin and beta-2 microglobulin | Hematology & Oncology |
| iStent | iStent (trabecular micro-bypass) | Tiny stent improving eye fluid drainage | Surgery |
| IT | intrathecal | Into the spinal canal, describing a medicine route | Prescription & Medication Orders Neurology |
| IT pump | intrathecal pump (implant) | Implanted pump delivering spinal medication | Surgery Neurology |
| ITB | iliotibial band (anatomy) | Thick band along the outer thigh | Musculoskeletal |
| ITBS | iliotibial band syndrome | Outer knee pain from irritation of the iliotibial band | Musculoskeletal |
| ITC | itraconazole (chart shorthand) | Azole antifungal chart shorthand | Prescription & Medication Orders Infectious Disease |
| ITP | immune thrombocytopenic purpura | Immune condition causing low platelets and bruising | Hematology & Oncology |
| ITR | inferior turbinate reduction | Procedure shrinking the lower nasal turbinate | General Medical Surgery |
| ITT | intention-to-treat | Analysing study participants in their assigned groups | General Medical |
| IU ⚠ Error-prone | international unit | Standard measure of substance activity, error-prone in writing | Prescription & Medication Orders Laboratory |
| IUC | indwelling urinary catheter | Tube left in place to drain urine | Renal & Nephrology Nursing |
| IUD | intrauterine device | Small device placed in the uterus for contraception | Obstetrics & Gynecology |
| IUGR | intrauterine growth restriction | Slow growth of a baby before birth | Obstetrics & Gynecology |
| IUI | intrauterine insemination | Fertility treatment placing sperm directly into the uterus | Obstetrics & Gynecology |
| IUP | intrauterine pregnancy | Pregnancy developing inside the uterus | Obstetrics & Gynecology |
| IUPC | intrauterine pressure catheter | Catheter measuring contraction strength inside the womb | Obstetrics & Gynecology Nursing |
| IUS | intrauterine system | Hormone-releasing device placed in the uterus for contraception | Obstetrics & Gynecology |
| IUT | intrauterine transfusion (procedure) | transfusing the fetus through the cord | Pediatrics Obstetrics & Gynecology Hematology & Oncology Surgery |
| IV | intravenous | Into a vein, describing a fluid or medicine route | Prescription & Medication Orders Nursing |
| IV access | intravenous access | A line into a vein for fluids or medicines | Emergency & Critical Care Nursing |
| IV ketamine | intravenous ketamine (depression treatment) | Infusion treatment for resistant depression | Psychiatry Prescription & Medication Orders |
| IVAC | infection-related ventilator-associated complication | Ventilator deterioration with signs of infection | Respiratory Emergency & Critical Care Infectious Disease |
| IVC | inferior vena cava | Large vein bringing blood from the lower body to the heart | Cardiology |
| IVC | involuntary commitment | Court-ordered psychiatric hospitalization | Psychiatry |
| IVC anatomy | inferior vena cava (anatomy) | Great vein returning lower body blood — anatomy | General Medical Cardiology |
| IVC collapsibility | inferior vena cava collapsibility | Ultrasound clue to fluid status | Cardiology Radiology & Imaging Emergency & Critical Care |
| IVCD | intraventricular conduction delay | Slowed electrical conduction within the lower heart chambers | Cardiology |
| IVF | in vitro fertilization | Fertility treatment where eggs are fertilised outside the body | Obstetrics & Gynecology |
| IVH | intraventricular hemorrhage | Bleeding into the fluid spaces of a premature baby's brain | Pediatrics Neurology |
| IVH neuro | intraventricular hemorrhage (adult) | Bleeding into the brain fluid spaces — adult | Neurology Emergency & Critical Care |
| IVI | intravitreal injection | Injection of medicine into the eye | General Medical Prescription & Medication Orders |
| IVIG | intravenous immune globulin (treatment) | Antibody infusion treatment — treatment | Pediatrics Prescription & Medication Orders Neurology Infectious Disease |
| IVIG jaundice | IVIG (hemolytic jaundice) | Antibody treatment reducing exchange need | Pediatrics Hematology & Oncology Prescription & Medication Orders |
| IVIG transplant | IVIG (desensitization) | Antibody treatment in transplant preparation | Renal & Nephrology Prescription & Medication Orders Surgery |
| IVP | intravenous pyelogram | X-ray imaging of the kidneys using contrast dye | Radiology & Imaging Renal & Nephrology |
| IVP order | intravenous push (order) | Medication given directly into the vein — order | Nursing Prescription & Medication Orders |
| IVPB | intravenous piggyback (order) | Medication infused through the main IV line — order | Nursing Prescription & Medication Orders |
| IVT | intravenous thrombolysis (stroke) | Clot-dissolving stroke treatment — treatment | Neurology Emergency & Critical Care Prescription & Medication Orders |
| IVU | intravenous urogram | Contrast X-ray imaging of the urinary tract | Renal & Nephrology Radiology & Imaging |
| IVUS | intravascular ultrasound | Ultrasound from inside a blood vessel to see its wall | Cardiology |
| IXA | ixazomib (chart shorthand) | Oral proteasome inhibitor shorthand | Prescription & Medication Orders Hematology & Oncology |
Educational reference only. This guide is for learning and quick reference. Abbreviations vary between hospitals, countries and specialties, and some are discouraged because they can be misread. Always write and interpret orders using your own institution’s approved abbreviation list, and check anything unclear with the prescriber or your local policy.