Medical Terminology curriculum

The root is the part a term is about, and it is most often a body part: "odont" is tooth, "myring" is eardrum and "dactyl" is a finger or toe. Find it by meaning, not by position. The same root can open one word and sit in the middle of another, as "cardi" does in cardiologist and myocardial.

Because the vowel is there for pronunciation, word-part lists often give a root both ways, as "gastr" and "gastro" or "cardi" and "cardio". The vowel is not a meaning, so it comes and goes: "carcin(o)" plus "-oma" gives carcinoma with no extra vowel, while "oste(o)" keeps its "o" before "-genic" in osteogenic.

Word-part lists usually show a root with its linking vowel attached, written as "osteo-" or "erythr(o)", so you learn one unit that attaches to many endings. "Osteo" plus "-genic" gives osteogenic, and "erythr(o)" plus "blast" gives erythroblast, a word built from two roots.

A prefix sits in front of the root and changes its meaning, often by adding size, shape, color, direction or amount. Swapping one prefix can reverse a word: hyperthyroidism is making more thyroid hormone than the body needs, and hypothyroidism is having too little. Not every term has a prefix, so many words start straight with the root.

A suffix ends the term and often names a test ("-scopy"), a problem ("-itis") or a description ("-eal", pertaining to). A new suffix can be built from a root plus an ending, as "-graphy" comes from "graph" plus "y". Suffixes alone never combine into a word, though; there must be a root to attach to.

A plain-English definition often starts with what the ending says, then the prefix, then the root. Transesophageal splits into "trans-" (across), "esophag" (esophagus) and "-eal" (pertaining to), so it reads as pertaining to across the esophagus. Check the result against how clinicians use a word: to a doctor, heart attack means damage to heart muscle, while a heart that stops beating is a cardiac arrest.

When a term holds several roots, read them as a list. Esophagogastroduodenoscopy names the esophagus, stomach and duodenum, the order an endoscope passes through them from the mouth, and ends in "-scopy", viewing. Erythroblast shows the plainest case: two roots, "erythr" and "blast", joined with no prefix or suffix.

Medical English draws on both Greek and Latin, so one structure can have two roots. A vein is "phleb" in phlebitis but "ven" in intravenous, and word-part lists give the eardrum both "tympan" and "myring". Learn both, because knowing one will not help you spot the other.

Many terms keep Latin plural endings instead of adding "s". A singular in "-a" takes "-ae" (mucosa, mucosae), one in "-us" takes "-i" (fungus, fungi), and one in "-um" takes "-a", as Latin bellum becomes bella. A term in "-is" can take "-es": synarthrosis becomes synarthroses. Learn each word as a pair.

One letter can move a term to a different place. The ileum is the last, narrowest part of the small intestine; the ilium is the largest hip bone. Mucus is the secretion itself, while mucous describes what makes it, as in mucous membrane. The perineum is a surface region near the anus; the peritoneum is the membrane lining the abdomen.

Several terms begin with a letter you do not hear. Pneumonia is said "noo-MOH-nyuh", ptosis "TOH-sis" and psychiatrist "sy-KY-uh-trist". If a word you heard seems missing from an index under N, T or S, try PN, PT or PS.

An eponym is named for a person or a place, so its parts tell you nothing: Lou Gehrig’s disease is another name for amyotrophic lateral sclerosis, or ALS. Acronyms decode only letter by letter, and a hurried hand can blur them, which is why the heart tracing is often written EKG to keep it apart from the brain test, EEG.

"-itis" names inflammation in whatever the root names: pharyngitis (throat), myositis (muscle), bursitis (bursa). It does not say why. Inflammation is the body’s response to injury or infection, so the word alone does not tell you whether germs are involved. Watch the "-osis" neighbor: osteoarthritis is a joint problem, while osteoporosis weakens bone.

Several endings mean condition: "-osis" (usually an abnormal one), "-ia", "-ism" and "-esis". "-iasis" adds the idea of something forming, as in lithiasis, stones forming in hollow organs such as the gallbladder or kidney ("lith" means stone). Because these endings say little beyond condition, the root carries the meaning.

"-emia" means a condition of the blood, and the rest of the word says what is in it and how much: hypercholesterolemia is an abnormally high level of cholesterol in the blood. The prefix carries the direction, so swapping "hyper-" for "hypo-" reverses the meaning. The ending "-uria" does the same job for urine.

Both "-algia" and "-dynia" mean pain, and some lists also gloss "-dynia" as swelling. The root says where it hurts: metatarsalgia is pain in the region of the metatarsus. Pain is a symptom rather than a cause, so a pain word tells you where it hurts without saying why.

"-megaly" says an organ is enlarged without saying why. "-trophy" and "-plasia" both translate as growth but describe different things: hypertrophy is added bulk from bigger cells and accumulated fluid, while hyperplasia is an increase in the number of cells. "-poiesis" means production, which names making something rather than its size.

"-pathy" means disease in general, so retinopathy, from "retin" (retina), is disease of the retina. "-oma" means tumor or mass, and it does not mean cancer by itself. A lipoma is a benign tumor made of fat cells, and only some "-oma" words, such as melanoma, name a cancer.

"-rrhage" means bleeding, as in hemorrhage, a loss of blood from damaged vessels. "-rrhea" means flow or discharge, as in diarrhea, frequent or uncontrollable bowel movements that may be soft, loose or watery; the ending names the flow, not blood. "-rrhaphy" is different again: it means a surgical suture, a repair rather than a symptom.

"-penia" means a lack, so neutropenia is a lower-than-normal number of neutrophils, a kind of white blood cell. "-cytosis" points the other way: lymphocytosis is an excess of lymphocytes in the blood. "-poiesis" means production, and "-sclerosis" hardening, as in atherosclerosis, where artery walls thicken and lose elasticity.

"-ectomy" means cutting out or removal. The suffix does not settle how much is taken: a colectomy can remove all or part of the colon, and when only part is removed it is called a partial colectomy. Qualifiers such as partial or segmental carry the amount, so read the whole name before assuming an organ is gone.

"-otomy" is an incision and "-ostomy" an opening, so a craniotomy is a cut into the skull while an ostomy makes a stoma, an opening from inside the body to the outside. An ileostomy, for example, opens the ileum to the outside and gives waste a new path out after part of the intestine is removed.

"-plasty" is surgical reconstruction of whatever the root names. "-rrhaphy" means suturing; a herniorrhaphy repairs an abnormal opening that tissue pushes through. "-pexy" fixes something in place, as orchiopexy secures an undescended testicle inside the scrotum. Reconstruct, stitch, fix: three different repairs.

"-scopy" is looking with an instrument and "-scope" is the instrument, so in a laparoscopy a laparoscope, a thin tube with a light and lens, is passed through the abdominal wall to view the inside. "-opsy" also glosses as visual examination, but a biopsy goes further: it removes cells or tissue for a pathologist to examine.

"-graphy" is the process of recording and "-gram" the record it produces. Echocardiography records the heart’s size and motion with ultrasound, and the result is an echocardiogram. The ending is the discriminator: it tells you whether a word names the test being done or what the test leaves behind.

"-centesis" is a surgical puncture to remove fluid: arthrocentesis draws fluid from a joint cavity, and paracentesis withdraws it from a body cavity. "-desis" means surgical binding, so arthrodesis binds a joint. One drains a space; the other binds parts together.

"-lysis" means breakdown or dissolving, and it need not be a procedure: hemolysis is the destruction of red blood cells by many causes. "-tripsy" means crushing, so lithotripsy breaks up a stone in the kidney, ureter, bladder or gallbladder. "-iatry" means medical treatment, and "-iatrist" the person who gives it.

"-meter" is a measuring device and "-metry" the measurement, so spirometry measures the volume of air breathed in or out. "-opsy" means viewing, and with "bio-" (life) it gives biopsy: removing specimens from the living body for a pathologist to examine.

"Intra-" means within, "inter-" between and "extra-" outside or beyond, after the Latin words intra, inter and extra. The first two differ by one letter. An intravenous injection goes into a vein, while the intercellular matrix fills the spaces between cells. Misread the prefix and you put the structure in the wrong place.

"Sub-", "infra-" and "hypo-" can all mean below. Subcutaneous means beneath the skin, and muscle names use "sub-" and "infra-" for position. "Hypo-" is the tricky one: besides under, it means deficient, so hypokinesia is slow or diminished movement, not movement beneath something.

"Supra-" and "super-" mean above, and "epi-" means upon or on the outside of. Muscle names use "supra-" for position, and epigastric refers to the upper middle area of the abdomen. "Hyper-" can also mean above, but it often means excessive, as in hypercholesterolemia, too much cholesterol in the blood.

"Peri-" and "circum-" both mean around. The pericardium is the sac that surrounds the heart and the roots of its great vessels. Compare "epi-", upon: the epicardium is the layer lying on the heart itself, the visceral layer of the serous membrane that also lines the sac. One prefix wraps a structure; the other rests on it.

"Endo-" means within or inner, while "ecto-" and "exo-" mean outer or outside. Endocrine glands have no ducts and release hormones straight into the blood; exocrine glands send their secretions through a duct to a surface or cavity. The endocardium is the heart’s innermost layer.

"Pre-" and "ante-" mean before or in front, "post-" behind or after, and "retro-" backward or behind. Each can mark time or place, and the root tells you which. Postoperative refers to the period after an operation, a time, while retroperitoneal refers to the space at the back of the abdominal cavity, a place.

"Trans-" and "dia-" mean across or through, and "per-" means through. In a transesophageal echocardiogram, the heart is imaged with ultrasound from a tube swallowed into the esophagus. A percutaneous route passes through the skin. In diarrhea, "dia-" joins "-rrhea" (flow).

"Ab-" means away from and "ad-" toward, after the Latin ab (from) and ad (to). One letter separates the muscle names abductor and adductor, which act in opposite directions. Afferent and efferent make a similar pair in lymph nodes: afferent vessels carry lymph into a node, and efferent vessels carry it away.

"Mono-" and "uni-" mean one, "bi-" two and "diplo-" double. Unilateral has to do with one side of the body and bilateral affects both sides, and the biceps is named for its two heads. Diplopia is double vision, in which one object is seen as two, so the prefix counts what is seen rather than the eyes.

"Tri-" means three, "tetra-" and "quadri-" four, and "multi-" and "poly-" many, while "olig-" means few or little. The triceps has three heads and the quadriceps four. Polyuria is passing a large volume of urine and oliguria is urine output below normal, so the prefix alone reverses the finding.

Word-part lists give "hemi-" and "semi-" the same gloss, half, but in hemiplegia "hemi-" names a side, not a measured fraction: it is severe or complete loss of movement on one side of the body. Milder one-sided weakness is hemiparesis, so the ending, not the prefix, tells you how severe the loss is.

"Macro-" and "mega-" mean large and "micro-" small, and "-megaly" is the ending for enlargement. A macrophage is a white blood cell that kills microbes and removes dead cells, and megakaryocytes are very large bone-marrow cells whose pieces become platelets. Megacolon is dilatation of the colon, and it has several different causes.

"Hyper-" means above, beyond or excessive and "hypo-" under or deficient. In terms for levels and activity they read as too much and too little: hypercholesterolemia is too much cholesterol in the blood, and hypokinesia is slow or diminished movement. The same prefixes can also carry a positional sense, so read the root before choosing.

"A-" and "an-" mean without or lacking, and "anti-" and "contra-" mean against. Compare anuria, absence of urine formation, with asymptomatic, having no signs or symptoms of disease: the prefix is "an-" before the vowel and "a-" before the consonant. Check the root as well, since "anti-" also begins with "an" but means something else.

"Dys-" means difficult or abnormal and "mal-" means bad. Dysphagia is difficulty swallowing and dyskinesia is abnormal involuntary movement, which shows both senses, while malnutrition is not getting enough calories or key nutrients. Do not confuse "dys-" with "dis-", which means separation or taking apart.

"Tachy-" means fast and "brady-" slow, so tachypnea is an increased breathing rate. The prefix gives a direction, not a cutoff: two federal definitions of an abnormally slow adult heart rate put the line 10 beats per minute apart, one of them hedged with "usually". A slow rate can also be normal, especially in people who are young or physically fit.

"Neo-" means new and "re-" again, and "pre-" and "post-" mean before and after. A neoplasm is new growth, an abnormal mass of tissue. Recurrence and relapse both describe a return: the National Cancer Institute’s dictionary uses recurrence for cancer that comes back after a time when it could not be detected, and relapse for any disease or its symptoms returning after improvement.

"Eu-" means good or well, "normo-" normal and "ortho-" straight, normal or correct. They contrast with problem prefixes such as "dys-", difficult or abnormal. Pick the sense that fits the root: in orthostatic hypotension, a drop in blood pressure after standing, read "ortho-" as straight rather than normal.

Color roots describe what is seen: "erythr" red, "leuk" white, "cyan" blue, "melan" black, "xanth" yellow and "chlor" green. Cyanosis is blue-colored skin from too little oxygen in the blood, and melanoma begins in melanocytes. Leukemia shows the limit: it is a cancer of blood-forming tissue, not white blood.

A sagittal plane runs front to back and divides right from left; only the median plane, through the midline, gives equal halves. A coronal, or frontal, plane runs side to side and separates front from back. A transverse, or axial, plane is horizontal and separates upper from lower.

Superior, or cranial, means toward the head end of the body; inferior, or caudal, means away from it. These words compare one structure with another rather than naming fixed places, so the same organ can be superior to one structure and inferior to another.

Anterior, or ventral, means front, and posterior, or dorsal, means back: the kneecap is on the anterior side of the leg and the shoulder blades on the posterior side of the body. The same pair names the main body cavities, the smaller dorsal cavity around the brain and spinal cord and the larger ventral cavity in front.

Medial means toward the midline of the body and lateral away from it, so the little toe is on the lateral side of the foot. The midline is the median plane, which divides the body into right and left halves. Like other directional terms, these compare one structure with another.

Proximal means nearer the trunk or a part’s point of origin, and distal farther from it: the hand is at the distal end of the forearm, and the proximal end of the femur meets the pelvis. The pair is not limited to limbs; the ileum, for example, is described as the distal part of the small intestine.

Superficial refers to the surface, and fascia shows the contrast with deep: superficial fascia lies just below the skin, while deep fascia wraps muscles, nerves and organs. Lying positions have their own words: supine is lying face up and prone is lying face down.

The dorsal cavity is the smaller one at the back: its cranial part holds the brain and the vertebral canal holds the spinal cord. The larger ventral cavity is split by the diaphragm into the thoracic cavity, with the heart and lungs, and the abdominopelvic cavity, with most of the digestive tract and the urinary and reproductive organs.

The chest is not one open space. Each lung sits in its own pleural cavity, the space between two layers of pleura that holds a thin film of fluid. Between the lungs lies the mediastinum, which contains the heart and its large vessels, the trachea, esophagus, thymus and lymph nodes, but not the lungs.

Serous membranes line cavities that do not open to the outside and cover the organs inside them. Each has a parietal layer on the cavity wall and a visceral layer on the organ: the parietal peritoneum lines the abdominal wall and the visceral peritoneum covers the organs. The pleura and pericardium follow the same pattern.

Many region words come from roots: axillary refers to the armpit, or axilla, inguinal to the groin, cervical to the neck and brachial to the arm. Lymph nodes cluster in three of these superficial regions on each side of the body: the inguinal, axillary and cervical regions.

"Cyt" means cell and "hist" tissue. Cytology is the study of cells under a microscope and histology the study of tissues, while "-cyte" ends cell names such as megakaryocyte, a very large cell in the bone marrow. A tissue is a group of cells with similar structure that work together as a unit.

The body has four main tissue types: epithelial, connective, muscle and nerve. Their roots show up everywhere, as "my" for muscle, "neur" for nerve, and "adip" or "lip" for fat. Fat is a connective tissue, alongside cartilage, bone and blood, and a lipoma is a benign tumor made of fat cells.

"-plasia" means growth, and the prefix says what kind. Hyperplasia is an increase in the number of cells, which still look normal. Dysplasia is the presence of abnormal cells in a tissue; it is not cancer, though it may sometimes become cancer. A neoplasm is new growth: an abnormal mass of tissue.

Neoplasm and tumor mean the same thing: an abnormal mass that forms when cells grow and divide more than they should or do not die when they should. Benign means not cancer; benign tumors can grow but do not invade or spread. Malignant cells can invade and spread. In situ means in the original place, so carcinoma in situ has not spread.

Acute describes signs or symptoms that begin and worsen quickly, while a chronic disease usually lasts three months or longer. Idiopathic means of unknown cause, congenital means present at birth, and iatrogenic means resulting from treatment by a health professional. A nosocomial infection is one caught in a health care setting.

A symptom is something a person feels and reports, such as pain or nausea; a sign is something someone else can find, such as fever or swelling. A syndrome is a set of symptoms or conditions that occur together. Diagnosis identifies the condition, etiology is its cause, and prognosis is its likely outcome.

Skin appears as "derm" in intradermal, within the skin, and as "cutane" in subcutaneous, beneath the skin, and percutaneous, through the skin. The two can even swap: intradermal and intracutaneous mean the same thing. Knowing both roots lets you place a word in the skin when the rest is new.

"Onych" means nail, so onychomycosis is a fungal infection of a nail. "Hidr" means sweat, as in hyperhidrosis, excessive sweating, and it is easy to misread as "hydr", which means water. Sebaceous glands in the dermis secrete sebum, an oily substance, and most open into hair follicles.

A lesion name describes how a spot looks at one moment. A papule is a small, solid, raised bump with clear edges, while a blister holds fluid within or beneath the epidermis. Because lesions change, one rash can pass through several names: CDC describes smallpox lesions moving from macules to papules to vesicles, then pustules.

Dermatitis is any inflammation of the skin. Urticaria is the formal name for hives, itchy raised red areas, while pruritus is itching itself, a symptom rather than something you can see. Alopecia is hair loss, and cyanosis is a bluish color of the skin and mucous membranes, from "cyan", blue.

"Oste" means bone, "cost" rib, and both "spondyl" and "vertebr" mean vertebra. "Myel" is the trap: it can mean bone marrow or the spinal cord, so read the rest of the word. Two National Library of Medicine lists disagree on "crani": its tutorial says skull and its word-part appendix says brain. Craniotomy, an incision into the cranium, shows the skull sense.

Each name is a joint or bone root plus a procedure suffix. Arthroplasty rebuilds a joint, arthrocentesis punctures a joint to draw off fluid, and arthrodesis binds a joint surgically. A laminectomy removes all of a vertebral lamina, the thin back wall of the arch around the spinal cord; removing part of it is a laminotomy.

"Arthr" means joint, as in arthroscopy, examining a joint with an endoscope. "Chondr" means cartilage, which is formed by cells called chondrocytes, and "burs" means bursa, a small fluid-filled sac between a bone and other moving parts. Synovial refers to the synovial membrane, which lines freely movable joints and secretes fluid into the joint cavity.

The spine runs through regions: seven cervical vertebrae in the neck, 12 thoracic in the upper back and five lumbar in the lower back, then the sacrum and coccyx. A level is written as a letter and number, such as C3, T2 or L4. Counts at the bottom vary by source, so the coccyx may be given as four vertebrae or three to five.

A comminuted fracture breaks a bone into several pieces. Open means a wound connects with the break and closed means it does not, so the pair describes the skin, not how badly the bone is broken. A pathologic fracture is caused by disease, a stress fracture by repetitive strain, and a compression fracture by pressure that collapses the bone.

Each name decodes from its parts. Osteoporosis is a loss of bone mass that can lead to fractures, and osteomyelitis is inflammation of bone from infection. Kyphosis, from "kyph" (humped), is a rounded outward curve of the upper back; scoliosis, from "scoli" (twisted), is a sideways curve. Ankylosis means a joint is fixed and immobile.

"-plegia" means paralysis, and the prefix says how much of the body is involved. Hemiplegia affects one side, paraplegia the lower body and legs, and quadriplegia, also called tetraplegia, all four limbs. Word-part lists gloss "para-" as alongside or abnormal, which does not predict the legs, so learn paraplegia as a whole word.

"My", "myo" and "muscul" mean muscle, as in myositis, inflammation of a muscle. The tendon root appears in tendinopathy, overuse injury of a tendon with pain, swelling and impaired performance. Fascia is layered connective tissue: superficial fascia lies just under the skin, and deep fascia wraps muscles and nerves.

"-plegia" is paralysis and "-paresis" milder weakness. Ataxia is impaired coordination of smooth voluntary movement, and "-kinesia" refers to movement, as in dyskinesia, abnormal involuntary movements. Word-part lists also give "-praxia" and "-taxis" as movement endings, so check a definition rather than guessing from the sound.

Myalgia is muscle pain and myopathy is muscle disease. Atrophy is a decrease in size, which in muscle can follow aging, poor blood supply, immobilization or loss of nerve supply. Muscular dystrophies are a separate, inherited group with wasting and weakness. Fibromyalgia is a long-lasting disorder with pain and tenderness throughout the body.

Most skeletal muscle names describe a feature, and many combine several: size (maximus), shape (deltoid), fiber direction (rectus, oblique), location (pectoralis), number of origins (biceps), attachments (sternocleidomastoid) or action (flexor, adductor). Decoding the name often tells you where a muscle is and what it does.

Supination turns the forearm so the palm faces forward or up, and pronation turns it backward or down. The same two words describe combined movements of the foot, so check whether the hand or the foot is meant. Gait is a manner or style of walking, and flexor and extensor muscles are named for the movements they produce.

"Cardi" and "coron" refer to the heart, and the wall layers build on "cardium": the endocardium is the inner layer, the myocardium the muscle in the middle, and the epicardium the outer layer. The pericardium is the sac around them. "Valvul" means valve, as in valvuloplasty, widening a narrowed heart valve.

"Angi" and "vas" or "vasc" mean blood vessel, "arteri" artery, and both "ven" and "phleb" mean vein. The two vein roots appear in different words, so learn them as a pair: intravenous describes something put into a vein, and phlebitis is inflammation of a vein. Knowing "ven" alone would not help you read the second.

A thrombus is a blood clot that forms in a vessel, while an embolus is whatever blocks a vessel after being carried in the bloodstream, a clot or other undissolved material. An aneurysm is a sac-like bulge in a weakened vessel wall, varicose veins are enlarged and twisted, and atherosclerosis is thickening and stiffening of artery walls as plaque forms.

These terms trace what happens when blood flow fails. Stenosis is narrowing ("steno") and occlusion is blockage, as in a coronary occlusion, and either can cause ischemia, hypoperfusion, meaning too little blood flow through a tissue. Infarction is tissue death caused by local ischemia, so a myocardial infarction is death of heart muscle from a blocked blood supply.

An arrhythmia is any disturbance of the heart’s normal rhythm, whether in rate or in its electrical signals. Rate words pair the speed prefixes with "-cardia". Atrial fibrillation and atrial flutter are both rapid rhythms of the upper chambers that keep blood from being pumped well into the lower ones; one federal definition traces fibrillation to abnormal impulse generation and typical flutter to abnormal conduction.

Angioplasty repairs a vessel, often by widening a narrowed artery. Angiography is x-ray imaging of vessels after a contrast agent is injected, so it shows the problem rather than fixing it. Echocardiography records the heart with ultrasound, and cardiac catheterization places a catheter in the heart to diagnose or treat.

Abbreviation lists expand MI as myocardial infarction, CAD as coronary artery disease, CABG as coronary artery bypass graft, CHF as congestive heart failure and AFIB as atrial fibrillation. ECG and EKG both mean electrocardiogram; EKG helps keep a hurried note from being misread as EEG, a brain test.

"Hem" and "hemat" mean blood, and "-cyte" means cell. Erythrocytes are red blood cells and leukocytes are white blood cells. Platelets, also called thrombocytes, help form clots, which fits "thromb" (clot); they are pieces of megakaryocytes, very large cells in the bone marrow.

These words share "-emia", blood condition, but name different things. Anemia is too few red blood cells, hypoglycemia too little blood glucose, and septicemia disease from bacteria and their toxins spreading in the blood. Leukemia is a cancer of blood-forming tissue such as bone marrow, so the shared ending only tells you blood is involved.

Hemostasis is the process that stops blood flowing from vessels, through vessel contraction, clumping of blood cells and coagulation, the clotting-factor chain that forms a clot. An anticoagulant prevents or treats clots. A hemorrhage is blood loss from damaged vessels, and a hematoma is a pool of mostly clotted blood in a tissue or space.

"Lymph" means lymph, and "lymphaden" adds "aden" (gland) because lymph nodes are also called lymph glands; lymphadenopathy is disease or swelling of the nodes. "Splen" means spleen. The thymus, in the chest behind the breastbone, is also part of the lymphatic system, and the tonsils are masses of lymphoid tissue in the throat.

An antigen is any substance that makes the body mount an immune response against it, and an antibody is a protein that binds one specific antigen. An allergen is a substance that causes an allergic response. Anaphylaxis is an acute hypersensitivity reaction to an antigen met before, and immunocompromised means having a weakened immune system.

A CBC, or complete blood count, measures red cells (RBC), white cells (WBC) and platelets, plus hemoglobin (HGB) and hematocrit (HCT), the share of blood made up of red cells. PT and PTT, prothrombin time and partial thromboplastin time, both time how long plasma takes to clot, and they test different parts of the clotting pathway.

Nose terms use "rhin-", throat terms "pharyng-", voice-box terms "laryng-" and windpipe terms "trache-"; sinus terms keep the word itself, as in sinusitis. Keep pharynx and larynx apart: the pharynx carries both food and air, while the larynx in front of it is the organ of voice, which is why laryngitis can bring hoarseness.

The ending "-pnea" means breathing, so the prefix carries the meaning: apnea is a pause with no spontaneous breathing, dyspnea is difficult or labored breathing, and tachypnea is a fast breathing rate. Hypoxia uses the oxygen root instead, so it names oxygen that is too low rather than a breathing pattern.

"Bronch-" names the large airways that lead from the windpipe into each lung, and "pneum-" can mean either air or lung, so the rest of the word decides. "Pleur-" is the thin membrane around the lungs, though word-part lists also gloss it as rib. The alveoli are small outpouchings at the far end of the airways, past the bronchi.

Breathing words end in "-pnea". Hypercapnia names too much carbon dioxide in arterial blood, while hypoxia and hypoxemia mark oxygen that is too low. Hemoptysis is spitting up blood from the respiratory tract, which you tell apart from hematemesis, vomited blood that generally points to the upper digestive tract.

Atelectasis is lung with no air in it, collapsed or never fully inflated, while emphysema is enlarged air spaces beyond the terminal bronchioles. Pleural effusion and pneumothorax share one space, the pleural cavity: an effusion is fluid there and a pneumothorax is air or gas. An effusion is a sign of disease, not a diagnosis. Pneumonia is infection of the lung itself.

Bronchoscopy looks into the bronchi with a scope, and spirometry measures how much air goes in or out. Thoracentesis draws fluid or air out of the chest. Two ways into the windpipe differ by route: a tracheostomy is a surgical opening through the neck, while intubation passes a tube in through the mouth or nose with no opening made.

One root can take several endings: colonoscopy is endoscopy of the colon, a colostomy makes an opening between the colon and the body surface, and a colectomy removes the colon. A gastrostomy is an opening into the stomach, often for feeding. Cholecystectomy joins "chol-" (bile) and "cyst-" (bladder or sac), so it names surgical removal of the gallbladder.

Mouth terms use "stomat-" and stomach terms "gastr-", so do not let the look of "stomat-" pull you toward the stomach. The tongue has two roots, "gloss-" and "lingu-", that mean the same thing. "Esophag-" names the muscular tube between the throat and the stomach, and the word stays recognizable inside longer terms.

From the stomach, the small intestine runs duodenum, jejunum, then ileum, and the large intestine continues through the colon to the rectum and anal canal. The ileum, the last part of the small intestine, is easy to confuse with the ilium, a hip bone, so spelling decides which one a word means. "Proct-" covers the anus and rectum.

Liver terms use "hepat-", and "chol-" means bile, so "cholecyst-" names the gallbladder, the sac that stores bile. Gallstones anywhere in the bile system are cholelithiasis, with "lith-" for stone. ERCP, endoscopic retrograde cholangiopancreatography, is a test for problems in the liver, gallbladder, bile ducts and pancreas.

Dysphagia is difficulty swallowing and emesis is vomiting. Two blood signs are easy to mix up: hematemesis is vomited blood, fresh red or like coffee grounds, while melena is black, tarry stool holding degraded blood. Ascites is free fluid in the abdominal cavity, and anorexia is loss of appetite, a symptom as well as the defining feature of anorexia nervosa.

Enteral nutrition uses the gut, by mouth or through a tube such as a gastrostomy, while parenteral nutrition goes by another route, for example a vein. Absorption is uptake through the gut lining, and metabolism is the chemistry that turns it into energy and new material. NPO is a Latin abbreviation for nothing by mouth.

Reflux is backward flow of stomach contents into the esophagus, and ileus is stalled gut movement with no physical blockage. The suffix separates two pouch words: diverticulosis means pouches are present in the colon, while diverticulitis means they are inflamed. Cirrhosis is a liver rebuilt as fibrous bands around nodules, and a hernia is tissue pushing through its containing wall.

"-uria" means a condition in the urine, so the front of the word says what is found or how it feels: hematuria is blood, proteinuria is protein, glycosuria is sugar, and dysuria is painful urination. Volume words use the same ending, as in polyuria, a large volume. Glycosuria can come from high blood sugar or from a defect in the kidney itself.

The kidney has two roots, "nephr-" and "ren-", and "pyel-" points to the renal pelvis, the funnel that joins the kidney to the ureter. Ureter and urethra are the classic mix-up: the paired ureters carry urine from the kidneys to the bladder, and the urethra carries it from the bladder out of the body. "Cyst-" means bladder or sac.

Read these as a scale of output: polyuria is a large volume, oliguria is output below the normal range, and anuria means no urine is formed. Oliguria even has a measured cutoff, at or below 0.5 or 1 mL per kilogram per hour depending on age. Nocturia is about timing rather than total volume: frequent urination at night that breaks sleep.

Catheterization passes a tube into the bladder or kidney, and cystoscopy looks inside the bladder with a scope. Lithotripsy breaks up a stone by physical force, sometimes with focused shock waves and no surgery; dissolving a stone with acids does not count. Dialysis cleans the blood when the kidneys cannot, and urinalysis examines the urine by chemical, physical or microscopic means.

Nephrolithiasis is stone formation in the kidney, and pyelonephritis is inflammation reaching both the kidney tissue and its pelvis. Incontinence and retention are opposites: incontinence is involuntary loss of urine, while retention is being unable to empty the bladder. Uremia is waste the kidneys should clear building up in the blood.

UTI is a urinary tract infection, and GU means genitourinary, the urinary and sex organs together. Kidney tests appear as BUN, blood urea nitrogen, and GFR, glomerular filtration rate, and ESRD is end-stage renal disease. IVP, intravenous pyelogram, is an x-ray test of the urinary system, built on the same "pyel-" pelvis root.

The uterus root is "hyster-", the fallopian tube root "salping-", which simply means tube, and "vagin-" names the vagina. The ovary has two roots, "oophor-" and "ovari-", so oophorectomy and ovariectomy name the same surgery. The cervix is the neck of the uterus, the lower part that opens into the vagina.

Testis terms use "orchid-" or "orchio-", so orchitis is inflammation of a testis, and prostate terms use "prostat-". "Sperma-" and "spermato-" mean sperm. The vas deferens is the duct that carries sperm from the testis, rising from the scrotum to join the seminal vesicles.

Menarche is the first menstrual period and menopause the last, recognized only after 12 months without one. Between them, the prefix names the problem: amenorrhea is no menstruation, dysmenorrhea is painful menstruation, and menorrhagia is excessive bleeding during it. Bleeding unrelated to menstruation has a different name, metrorrhagia.

Each is a root plus "-ectomy", removal: hysterectomy removes the uterus, oophorectomy one or both ovaries, and salpingectomy one or both fallopian tubes. Read the ending carefully, because a hysterotomy, with "-otomy", is only an incision into the uterus. Circumcision removes all or part of the foreskin.

Endometriosis is uterine-lining tissue growing outside the uterus, while a fibroid, or leiomyoma, is a benign smooth-muscle tumor that rarely occurs outside the uterus and gut. Prostatitis is inflammation in the prostate. Cryptorchidism is a testis that never descended into the scrotum, and hypospadias is a urethral opening below its normal place.

STD stands for sexually transmitted disease, one spread by sexual contact. HPV, human papillomavirus, can cause cervical cancer, and a PAP test looks for that cancer in collected cells. PID is pelvic inflammatory disease, infection and inflammation of the female reproductive organs, and an IUD is an intrauterine device used for birth control.

Parturition is the process of giving birth, and lactation is milk secretion after it; "lact-" means milk. The amnion is the innermost sac around the developing embryo, bathed in amniotic fluid, which is why drawing that fluid is amniocentesis. As a biological span, pregnancy runs from fertilization to birth.

Gravidity is the number of pregnancies, counted whether or not they reached term, and parity is the number of offspring borne. The two can differ, because every pregnancy adds to gravidity but only a birth adds to parity, so neither number stands in for the other.

Early labor thins the cervix, called effacing, and opens it, called dilation. The first stage runs to full dilation, the second ends with the birth of the baby, and the third ends when the placenta is delivered. Presentation is the baby's orientation in the birth canal; the normal one is vertical and cephalic, a name taken from the part that comes first.

Amniocentesis passes a needle through the abdomen into the uterus to draw amniotic fluid, often to check the fetus's chromosomes. An episiotomy is an incision that widens the vaginal opening for delivery, and a cesarean section delivers the baby through a cut in the abdomen and uterus. Cervical cerclage stitches a weak cervix closed.

A newborn, or neonate, is an infant in the first 28 days. Preterm means born before 37 weeks, and a prolonged pregnancy runs past 42 weeks. Meconium is the thick green-to-black material that forms the first stools. The Apgar score rates five signs from 0 to 2 at one minute and again at five minutes, then adds them.

Preeclampsia is a sudden rise in blood pressure after week 20, often with signs of organ damage such as protein in the urine. Placenta previa and placental abruption both involve the placenta but differ in mechanism: previa is a placenta implanted low, over or near the cervix, while abruption is a normally placed placenta separating too early. An ectopic pregnancy implants outside the uterus, mostly in a tube.

"-phasia" names speech and "-phagia" eating or swallowing, so aphasia is impaired language and dysphagia difficult swallowing. Ataxia is impaired coordination of voluntary movement. "-plegia" means paralysis, and the prefix gives the extent: hemiplegia affects one side, paraplegia the legs and lower trunk, and quadriplegia all four limbs.

"Neur-" means nerve, "encephal-" brain, and "mening-" the three membranes covering the brain and spinal cord. "Myel-" is the trap: it can mean spinal cord or bone marrow, so the rest of the word decides. Keep two look-alike structures apart: the cerebrum is the two-hemisphere part of the brain, while the cerebellum lies behind the brainstem.

"-esthesia" means sensation and "-algesia" pain, and the prefix says which way it is off. Hypesthesia is reduced skin sensitivity and hyperesthesia increased, while paresthesia is tingling or warmth felt with no stimulus at all. Hyperalgesia is extra pain from a barely painful stimulus, and analgesia is pain relief.

Lethargy is sluggish, listless tiredness with trouble concentrating. Stupor is reduced response to stimuli, yet the person can still be roused by vigorous, repeated stimulation. Coma is the deeper state from which the person cannot be aroused. Syncope, or fainting, is different in kind, a brief loss of consciousness, usually from a sudden drop in blood flow to the brain.

Neuropathy is disease of the nerves, encephalitis is inflammation of the brain, and meningitis is inflammation of the meninges that cover it; the root tells you which structure. Hydrocephalus is too much cerebrospinal fluid inside the skull. A seizure is a sudden, disorderly burst of brain-cell activity, and recurrent seizures are what epilepsy names.

A lumbar puncture taps fluid from the space around the spinal cord, usually between the third and fourth lumbar vertebrae. Electroencephalography records the brain's electrical activity through electrodes. Craniotomy cuts into the skull, and myelography is x-ray imaging of the spinal cord after contrast is injected around it.

CNS is the central nervous system, the brain and spinal cord, and CSF is the cerebrospinal fluid around them. A CVA, cerebrovascular accident, is a stroke, and a TIA, transient ischemic attack, is a stroke that ends within minutes because the blood supply is blocked only briefly. EEG records the brain's electrical impulses. After head injury, the Glasgow Coma Scale scores eye opening, motor and verbal responses.

"Psych-" means mind, and the ending decides the rest: "-ology" is study, so psychology studies the mind, and "-iatry" is medical treatment, so psychiatry treats it. Other roots in this area describe a quality rather than a place: "schiz-" means split, so read each part separately before you translate the whole word.

Affect is the feeling tone that accompanies an idea. Euphoria is an exaggerated sense of well-being out of step with what is happening, and anhedonia is the inability to feel pleasure, a symptom of major depression and schizophrenia. Dysthymia, also called persistent depressive disorder, is less severe depression that lasts much longer, usually at least two years.

A delusion is a false belief held despite the facts, a hallucination is a sensation with no matching stimulus, and an illusion misreads a stimulus that is really there. Ideation means thoughts rather than acts: only a minority of people with suicidal ideation go on to self-harm, yet the term still names a recognized risk factor for attempts.

"-phobia" means fear, and a phobic disorder is a persistent, irrational fear of a specific object or situation that drives avoidance. Word-part lists give "-mania" as a morbid impulse toward an object, which differs from mania on its own, a state of elevated excitement and overactivity. An obsession is a persistent, unwanted idea or impulse.

Orientation is awareness of yourself in time, place and person. Short-term memory holds information for seconds to hours, and long-term memory reaches back years. Delirium and dementia both impair thinking but differ in course: delirium usually starts suddenly and is often temporary, while dementia is an acquired loss of intellectual abilities that is usually progressive.

ADHD is attention deficit hyperactivity disorder, OCD obsessive-compulsive disorder, and PTSD post-traumatic stress disorder; some lists expand the last as a syndrome, but the condition is named a disorder. SAD is seasonal affective disorder, depression during seasons with little light.

The eye has two roots, "ophthalm-" and "ocul-", and "op-" or "opt-" means vision. "Blephar-" is the eyelid, "irid-" the iris, and "retin-" the retina. "Kerat-" means cornea but can also refer to skin, so a "kerat-" word may not concern the eye at all; read the rest of the word before deciding.

Many vision conditions end in "-opia", from the vision root. Myopia, or nearsightedness, brings light to a focus in front of the retina, from a cornea that is too curved or an eyeball that is too long. Presbyopia is the lens losing its elasticity so focusing fails. Diplopia is seeing one object as two, and amblyopia, or lazy eye, is poor vision, usually in one eye.

A cataract is a cloudy area in the lens, while glaucoma is a group of eye diseases that damage the optic nerve; one clouds, the other injures a nerve. Keratoplasty replaces corneal tissue, and blepharitis is inflammation of the eyelids.

"Ot-" means ear and "acous-" hearing. The eardrum has two roots, "myring-" and "tympan-", and is the thin membrane between the ear canal and the middle ear. The middle ear holds the tiny ossicles and connects to the throat through the eustachian tube, and the inner ear lies beyond it as connected cavities: the cochlea, vestibular labyrinth and semicircular canals.

Presbycusis is gradual hearing loss in both ears that comes with aging, usually starting with high pitches. Tinnitus is hearing a sound, often ringing, that has no outside source. Vertigo is more specific than dizziness: an intense sensation of spinning. Cerumen is earwax, the waxy secretion of glands in the ear canal.

"Hyper-" means above normal and "hypo-" below, and "-ism" names a condition, so hyperthyroidism is too much thyroid hormone and hypothyroidism too little. The same pattern names the parathyroids: hyperparathyroidism is too much parathyroid hormone and hypoparathyroidism too little. The prefix describes hormone output, not gland size.

"Gluco-" and "glyco-" mean sugar. Hyperglycemia is high blood glucose, and glycosuria, an abnormal amount of glucose in the urine, can follow from it or from a kidney defect. "Poly-" means many or excessive, so polydipsia is excessive thirst, a feature of diabetes among other diseases, and polyphagia is excessive eating.

"Aden-" means gland, as does "adren-", which names the adrenal glands at the top of each kidney. "Thyr-" points to the thyroid, and the parathyroids, from "para-" meaning alongside, are small glands beside its two lobes. The pituitary is a small, unpaired gland, unlike the adrenals, which come as a pair.

Endocrine glands have no ducts and send hormones straight into the blood, while exocrine glands, such as sweat or salivary glands, release through a duct; the pancreas does both. Hormones act through receptors, molecules that bind them and trigger an effect. Some hormones drive other glands, which is what the "stimulating" in thyroid stimulating hormone, TSH, tells you.

A goiter is an enlarged thyroid, and it occurs with normal, low or high thyroid function, so size says nothing about output. Myxedema is the waxy swelling of thyroid hormone deficiency. Acromegaly is too much growth hormone in adults; the same excess before puberty ends causes gigantism. Cushing syndrome is excess cortisol, and Addison disease is too little.

TSH is thyroid stimulating hormone, and the thyroid hormones T3 and T4 carry the Greek numbers three and four, triiodothyronine and tetraiodothyronine. PTH is parathyroid hormone and FSH follicle stimulating hormone. DM is diabetes mellitus, which notes may also write as IDDM or NIDDM for type 1 and type 2. HbA1c, glycated hemoglobin, tracks average blood sugar.

"-oma" means tumor, but not every "-oma" is cancer: a lipoma is a benign fat tumor, while melanoma and lymphoma are cancers. The two malignant endings name tissue: carcinoma begins in the skin or the tissues that line or cover internal organs, and sarcoma in bone or soft connective tissue such as fat or muscle.

The root in front of the tumor ending gives the tissue: "aden-" gland, "lip-" fat, "oste-" bone, "melan-" black pigment, and "lymph-" lymph. Read it together with the ending: an adenoma is a benign gland tumor, an adenocarcinoma is a cancer of glandular tissue, and an osteosarcoma is a cancer of bone.

In situ means in its original place: abnormal cells that have not spread. Invasive cancer has grown beyond its layer of origin into nearby tissue, and metastatic cancer has spread from the primary site to other places. Differentiation describes resemblance to normal tissue: well-differentiated cells look more normal, while anaplastic cells look little like normal cells and divide rapidly.

The primary tumor is the first one, where the cancer began. Stage measures extent, such as tumor size, lymph node involvement and spread, as in TNM, where N records nodes. Grade measures appearance, how abnormal the cells look under a microscope. Remission means signs and symptoms have lessened or disappeared, which is not proof the cancer is gone.

An excisional biopsy removes the whole lump, while an incisional biopsy removes only a sample. A needle biopsy draws tissue or fluid through a needle: a wide needle gives a core biopsy and a thin one a fine-needle aspiration. A frozen section is tissue frozen and cut into thin slices with a cryostat for examination.

Neoadjuvant therapy comes first, to shrink a tumor before the main treatment, and adjuvant therapy comes after, to lower the risk of return. Palliative care treats symptoms and improves quality of life, while curative surgery aims to remove all the cancerous tissue. Cytotoxic agents kill cells, including cancer cells.

CA can mean cancer or calcium, so context must settle it. CA-125, cancer antigen 125, and PSA, prostate specific antigen, are blood tests, and BRCA names breast cancer genes. TNM summarizes tumor, nodes and metastasis. PET, positron emission tomography, images where injected radioactive glucose is taken up.

"-gram" is the picture itself, and "-graph" or "-graphy" is the process of making it, so a myelogram is the image and myelography the procedure that makes it. "-scopy" means using an instrument to look inside, as in colonoscopy. "-metry" is measurement, which is why spirometry gives numbers rather than a picture.

Radiography records an x-ray image, and CT rotates a narrow x-ray beam around the body to build cross-sectional slices. MRI uses a strong magnet and radio waves rather than ionizing radiation and shows soft tissue well. Ultrasound builds images from sound echoes, and nuclear imaging detects a radioactive substance injected into the body.

View names use directional words, anterior for front and posterior for back. One review of intensive care chest films says most are taken anteroposterior with the patient lying or sitting, which magnifies the heart, and an appearance normal on such a film can be abnormal on a posteroanterior one. It also describes a lateral decubitus film, taken lying on the suspected side, to confirm a small pleural effusion.

On x-rays and CT, dense structures such as bone show clearly, while soft tissues can look faint. X-ray contrast agents, also called radiopaque media, contain substances that stop x-rays, so a vessel or duct filled with them stands out; that added visibility is what enhancement refers to. MRI uses its own contrast agents, such as gadolinium, to help abnormal tissue show.

Ultrasound, or sonography, sends sound waves into the body and listens for echoes from tissue boundaries; the time each echo takes gives its distance, and the picture is a sonogram. Doppler ultrasound adds motion: it measures the speed and direction of blood flow, and color Doppler maps that flow in color.

A tracer is a carrier molecule bonded to a radioactive atom; once injected, it collects in particular tissues and a camera detects it. Uptake is how much a tissue takes in: on a PET scan, cancer cells often take up more of the radioactive glucose. These images show function, such as metabolism, rather than only structure.

CXR is a chest x-ray, CT or CAT computed tomography, MRI magnetic resonance imaging, and PET positron emission tomography. ECHO is an echocardiogram, a heart test using sound waves, and IVP an intravenous pyelogram of the urinary system. CT and CAT name the same scan, so two sets of letters do not always mean two tests.

Serum and plasma are both the liquid part of blood, but serum is what remains after blood clots, while plasma is separated without clotting and still holds the clotting proteins. Sputum is mucus coughed up from the lungs, not saliva, so spit is not a sputum sample. A swab collects cells or pus, for example from the throat or a wound.

A culture grows microorganisms from a sample in the lab, usually taking one to two days and longer for slow growers, so the organism can be identified. A sensitivity, or susceptibility, test then checks which antibiotic medicines that organism responds to. A blood culture looks for infection in the blood itself.

A complete blood count counts red cells, white cells and platelets and measures hemoglobin and hematocrit. A differential goes further, measuring each type of white blood cell. A comprehensive metabolic panel measures 14 substances; a basic metabolic panel covers 8 of them and leaves out total protein, albumin, bilirubin and liver enzymes.

A reference range is the span of results seen in large groups of healthy people, and it can differ between groups, so a value just outside it is not automatically a problem. Positive means the test found what it looked for, negative that it did not. A false positive reports a condition that is absent; a false negative misses one that is present.

Results are reported as amounts per volume, such as micrograms per deciliter, micromoles per liter or picograms per milliliter. A result is read against the range on its own lab report, since results from different labs cannot be compared directly. The prefix matters: a microgram is a thousandth of a milligram, which is why misreading mcg as mg causes a 1,000-fold error.

Common test abbreviations include CBC, complete blood count; BUN, blood urea nitrogen; ALT and AST, two liver enzymes; and PT and PTT, measures of blood clotting. ESR is a blood test for inflammation. Some letters collide: CA can mean cancer or calcium, so read the abbreviation in its context.

A generic name is not protected by a trademark, so several companies can make the drug under it, while a brand name is the proprietary name one company markets. An FDA-approved generic must match its brand in active ingredient, strength, dosage form and route, and must be bioequivalent to it.

Oral means by mouth, IV intravenous, into a vein, and IM intramuscular, into a muscle. Subcutaneous means beneath the skin, sublingual under the tongue, topical on the body surface, and transdermal absorbed through unbroken skin. FDA guidance on drug labels generally describes routes without abbreviation, and separately warns that IU, for international unit, has been confused with IV.

BID, from the Latin bis in die, means twice a day; TID is three times, QID four times, and PRN means as needed. Look-alike letters cause errors: SID, a veterinary once-daily notation, has been misread as BID or QID, TIW (three times a week) as three times daily, and qhs (at bedtime) as every hour.

A capsule holds medicine in a soluble shell, often gelatin, and a suspension carries a drug that will not dissolve in water through a liquid. A suppository is solid at room temperature but melts at body temperature after insertion into the rectum, vagina or urethra. A transdermal patch sticks to the skin and delivers a dose into the bloodstream.

FDA advice on avoiding medication errors, written for veterinarians, calls for writing out the drug name and the full regimen: dose, frequency, duration and route. Shorthand invites errors, since abbreviations are misread even when typed. Substitution replaces a prescribed drug with another expected to have the same effect, which is how a generic can stand in for its brand.

Many generic names share a stem, a fixed word part that signals a pharmacological or chemical trait, so one stem covers several drugs. It is a clue, not a guarantee: one published commentary on stems notes that some drugs in a class lack its stem, a few names only look as if they carry one, and drugs sharing a stem can still differ in effects and in how severe a shared risk is.

Therapeutic means having to do with treating disease, and an adverse effect is an undesired one. A side effect is broader: any effect beyond the intended one, harmful or beneficial. Synergistic drugs together do more than the sum of each alone. Prophylaxis is an attempt to prevent disease, and a contraindication is a reason a treatment could harm a particular person.

DX stands for diagnosis and Rx for prescription, and NKDA records no known drug allergies. Shorthand like this works only when writer and reader share the list: in one UK survey of 20 nonstandard abbreviations taken from patient records, only four were defined correctly by more than half of the staff asked.

The vital signs are pulse rate, breathing rate, body temperature and blood pressure, and the rates are usually counted per minute. Blood pressure is written as two numbers with a slash, because it is measured at two points in the heartbeat: as the heart pumps and as it fills between beats. Oxygen saturation, often from a pulse oximeter, records how fully hemoglobin carries oxygen.

A SOAP note runs Subjective, Objective, Assessment, Plan. One hospital audit checklist shows what each part holds: subjective for the chief complaint, history and current medicines; objective for vital signs, examination and investigations; assessment for provisional and differential diagnoses; and plan for further tests, consultations, medicines and follow-up.

NPO, from the Latin for nothing by mouth, marks a patient who is to take nothing orally. Resuscitation orders are a physician's instructions on starting, continuing or withdrawing life support. Both entries record an instruction about care, so neither describes how sick the patient is.

A handoff transfers information along with authority and responsibility, and responsibility does not pass until the receiver acknowledges it. SBAR structures the message as Situation, Background, Assessment, and Recommendation or Request. A check-back confirms it: the receiver repeats the message and the sender closes the loop by saying it is correct.

The same letters can stand for different things: CA can mean cancer or calcium, and even a word part such as "myel-" can mean spinal cord or bone marrow. In one survey of 20 abbreviations taken from patient records, three-quarters had at least one other meaning to the staff asked, so read letters in context or write the term out.

Some abbreviations are discouraged because they are misread in predictable ways, even when typed. In 2006 the FDA and the Institute for Safe Medication Practices began a national education campaign about them, and one survey report notes that some institutions keep their own do-not-use lists. Commonly misread ones include U for units, IU for international units, and SID for once daily.

A trailing zero hides the decimal point, so 5.0 mg can be read as 50 mg, and a missing leading zero does the same, so .5 mg can be read as 5 mg; either way the error is tenfold. The convention is whole numbers with no trailing zero and a zero before any decimal below one, as in 0.5 mg. FDA label guidance also calls for commas in numbers of 1,000 and above, to make them easier to read.

"U" for units can be read as a zero, so 1U looks like 10 and gives ten times the dose; insulin errors of this kind have been fatal. "IU" can be read as IV, the intravenous route. A microgram written with the Greek mu symbol can be read as mg, a 1,000-fold error, which is why mcg is the accepted abbreviation.

Some drug names differ by only a few letters and get mixed up. Tall man lettering capitalizes the part that differs, as in vinBLAStine versus vinCRIStine, so the eye catches the difference. Since 2001 the FDA has reviewed reports of name confusion and keeps a list of established names recommended for this lettering.

FDA labeling guidance groups error-prone symbols with the abbreviations and dose designations that get misread, and points to a published list of them. It treats a slash in a strength such as 50 mg/5 mL as generally acceptable, since clinicians are used to it. A decimal comma, common in Europe, has caused errors in the US, where labels use a decimal point.

A spoken or telephone order is confirmed by check-back: the receiver records the order and reads it back, and the sender closes the loop by confirming it is correct. It works because the receiver must show the message was understood, not just heard. Emails and texts carry their own risks, since they may go unread or be changed by autocorrect.

Everyday words can mean something else to a clinician: to many people a heart attack means the heart stopped, but to a doctor it means damage to heart muscle, and a stopped heart is cardiac arrest. Translate the built term, then check it landed with teach-back, where the patient explains it in their own words, since asking if they understand often gets a yes either way.