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iatrogenic describes a secondary condition arising from treatment of a primary condition.
icon a pictorial representation on a computer screen.
identity bracelet a plastic band attached to either a patient’s wrist or ankle when they are admitted to hospital, usually giving their name and patient number; it should not be removed until a patient leaves hospital.
idiopathic scoliosis characterized by a lateral curvature of the spine together with rotation and associated rib hump or flank recession. The treatment is by spinal brace or traction or internal fixation with accompanying spinal fusion. See also halopelvic traction, Harrington rod, Milwaukee brace.
IHE (Integrated Health Enterprise) a consultation exercise between manufacturers and health professionals to ensure that computerization of the healthcare system achieves what the users require.
ileal conduit a surgical procedure when the ureters are attached to the ileum, part of the ileum then forms a reservoir for urine which drains to the anterior abdominal wall through a fistula.
ileocaecal associated with the ileum and the caecum.
ileocolic associated with the ileum and the colon.
ileorectal associated with the ileum and the rectum.
ileostomy a surgically made fistula between the ileum and the anterior abdominal wall; a type of opening (stoma) discharging liquid faecal matter. Usually permanent when the whole of the large bowel has to be removed, for example, in severe ulcerative colitis.
ileostomy bags special plastic bags used to collect the liquid discharge from an ileostomy.
ileum the lower three-fifths of the small intestine, lying between the jejunum and the caecum. Concerned with the absorption of various nutrients such as vitamin B12.
ileus intestinal obstruction. Usually restricted to paralytic as opposed to mechanical obstruction and characterized by abdominal distension, vomiting and the absence of pain.
iliac associated with the ilium. iliac arteries carry arterial blood to the pelvis and legs.
iliac crest the highest point of the ilium.
iliac region/fossa the abdominal region situated either side of the hypogastrium.
iliac veins drain venous blood from the legs and pelvis.
iliococcygeal associated with the ilium and coccyx.
iliofemoral associated with the ilium and the femur.
iliopectineal associated with the ilium and the pubis.
iliopectineal line bony ridge on the internal surface of the ilium and pubic bones. It is the dividing line between the true and false pelvis.
iliopsoas associated with the ilium and the loin.
ilium the upper part of the innominate (hip) bone; it is a separate bone in the fetus.
Ilizarov frame external fixation device used commonly in the management of fractures of the tibia.
image acquisition the collection of data in order to produce a computed tomography or magnetic resonance image.
image acquisition time the scanning time required to produce a set of images from a measurement sequence in magnetic resonance imaging. For a two-dimensional sequence it is the repetition time, times the number of signal excitations/averages times the number of phase encoded steps. For a fast two-dimensional sequence it is the two-dimensional sequence divided by the echo train length. For three-dimensional volume sequence it is the two-dimensional sequence multiplied by the number of partitions.
image annotation the marking of information on a radiograph to denote the side of the body, the patient position and the exposure factors; digital systems allow preset terms, numbers and letters to be added alongside the patient image.
ImageChecker™ an aid to screening routine mammograms by automatically marking clusters of white areas and dense areas with radiating lines.
image format the manner in which a computed tomography image is stored or displayed such as on screen, computer disk, magnetic tape or film.
image intensifier a means of producing a real time image of a patient. The X-ray beam passes through the patient and onto the image intensifier which converts the image to light, this image is scanned and an electrical signal is sent to a television monitor where the image is viewed.
image manipulation in CT scanning the ability to digitally alter the appearance of the acquired image to enhance depiction of the required anatomy.
image quality the ratio of signal over noise.
image reconstruction the process of producing an image from computer data or a set of unprocessed measurements.
image segmentation in digital imaging, dividing an image into its various parts or taking the image from the background to increase the definition of the object.
imaging plate a re-usable plate coated with barium phosphate that, when exposed to radiation excites the electrons, and then, when scanned by a helium-neon laser, produces an image which can be recorded.
imaging techniques diagnostic techniques used to investigate the condition and functioning of organs and structures. They include radiographic examination, radionuclide scans, ultrasonography, computed tomography, magnetic resonance and positron emission tomography.
imbalance want of balance. Term refers commonly to the upset of acid–base relationship and the electrolytes in body fluids.
immersion foot see trench foot.
immobilization device a method of reducing movement during radiotherapy treatment or diagnostic imaging.
immobilize to keep from moving, splints or plaster of Paris bandages are used to prevent realigned broken bones from becoming displaced.
immune protected against infection by specific or non-specific mechanisms of the immune system. Altered reactivity against an antigen, caused by previous exposure to that antigen.
immune response the response of the immune system to a perceived threat, either from non-self antigens, or from self antigens during a pathological immune response. This may be against microorganisms, malignant cells, and damaged or healthy tissues.
immunity an intrinsic or acquired state of immune responsiveness to an antigen. active immunity is acquired, naturally during an infection or artificially by immunization. It involves the production of antibodies and specific T cells in response to exposure to an antigenic stimulus. The primary response to exposure is followed by a lag phase of 2–3 weeks before enough antibodies are produced, but the secondary response following a subsequent exposure is more intense and has a much reduced lag phase because the memory cells are able to produce antibodies very quickly. This type of immunity tends to be of long duration. cell-mediated immunity T-lymphocyte-dependent responses which cause graft rejection, immunity to some infectious agents and tumour rejection. humoral immunity from immunoglobulins produced by plasma cells derived from B lymphocytes. Immunity can be innate (from inherited qualities), or it can be acquired, actively or passively, naturally or artificially. passive immunity is acquired, naturally when maternal antibody passes to the fetus via the placenta or in colostrum and breast milk, or artificially by administering immunoglobulins (usually human in origin). This type of immunity tends to be short-lived because the immune response is not stimulated to produce specific antibodies.
immunization a process by which resistance to an infectious disease is induced or increased.
immunocompromised patients (immunosuppressed patients) patients with defective immune responses, which can be inherited or acquired. Often produced by treatment with drugs or irradiation. Also occurs in some patients with cancer and other diseases affecting the lymphoid system. Depending on the immune defect, different patterns of infection result. Patients with cellular defects are likely to develop infections with opportunistic organisms such as Candida, Pneumocystis carinii and Cryptococcus neoformans. Patients with antibody defects are more liable to infections with encapsulated bacteria such as pneumococcus.
immunocytochemistry staining cells with specific antibodies for diagnostic purposes.
immunodeficiency the state of having defective immune responses, leading to increased susceptibility to infectious diseases.
immunoglobulins (Igs) (antibodies) high-molecular-weight glycoproteins produced by plasma cells (derived from B lymphocytes) in response to specific antigens. The basic structure of immunoglobulins is Y-shaped, consisting of two identical heavy chains, each linked to two identical light chains. Immunoglobulins are found in the blood and other body fluids where they form part of body defences. Immunoglobulins function in a variety of ways, but all involve combining with the antigen to form an immune complex. There are five classes of immunoglobulins, IgG, IgA, IgD, IgM and IgE, each with different characteristics, functions and locations.
immunohistochemistry staining tissue with specific antibodies for diagnostic purposes.
immunological response see immunity.
immunology the study of the immune system of lymphocytes, inflammatory cells and associated cells and proteins, which affect an individual’s response to antigens.
immunosuppression the administration of agents to significantly interfere with the ability of the immune system to respond to antigenic stimulation by inhibiting cellular and humerol immunity. May be deliberate such as before bone marrow transplants to prevent rejection by the host or incidental such as following chemotherapy for the treatment of cancer.
immunosuppressive that which reduces immunological responsiveness. Describes an agent such as a drug that suppresses immune system function.
immunotherapy the use of knowledge about immunity to prevent and treat disease. Can be used to mean desensitization therapy against specific allergens, for example, insect venom, or can refer to therapeutics which use agonists or antagonists based on immune system components, for example, treatment based on biological modifiers such as interleukin-2.
impacted firmly wedged, abnormal immobility, for example, faeces in the rectum; a fetus in the pelvis; a tooth in its socket or a calculus in a duct.
impacted fracture a break in bone continuity when the ends of the bone overlap, the most common site is just above the wrist joint.
impedance the general opposition of flow of electric current measured in ohms. In ultrasound a measure of the tissue’s resistance to distortion by ultrasound and depends on the tissue density and the velocity of the sound.
imperforate lacking a normal opening.
imperforate anus a congenital absence of an opening into the rectum.
imperforate hymen a fold of mucous membrane at the vaginal entrance which has no natural outlet for the menstrual fluid.
implant any drug, structure or substance inserted surgically into the human body, for example, implants of progestogens for contraception, or implants used in plastic surgery. Those used to augment tissue contour may be of two types: alloplastic synthetic foreign body implants such as those used in breast reconstruction, or autologous implants tissue obtained from the same patient. dental implant artificial structure implanted surgically into the alveolar bone, usually made from titanium.
implantation the insertion of living cells or solid materials into the tissues, for example, accidental implantation of tumour cells in a wound; implantation of radioactive material or solid drugs; implantation of the fertilized ovum into the endometrium.
incidence rate the total number of new cases, of a specific disease, occurring in a given period of time among a given number of people.
incident beam the beam of radiation striking an object.
incident light the light travelling from the light source.
incipient initial, beginning, in its early stages.
incision in surgery, a cut into soft tissue, the act of cutting.
incisional hernia protrusion through the site of a previous abdominal incision.
incisor tooth an anterior tooth with a cutting edge and single root, placed first and second from the midline in both primary and secondary dentition.
incompetence inadequacy to perform a natural function, for example, mitral valve regurgitation.
incomplete abortion a termination of pregnancy or a miscarriage when the products of conception are not fully expelled or removed. See also miscarriage.
incomplete fracture the bone is only cracked or fissured, called greenstick fracture when it occurs in children.
incomplete miscarriage part of the fetus or placenta is retained in the uterus. See also evacuation of retained products of conception.
incontinence inability to control the evacuation of urine or faeces. See also functional incontinence, neurogenic incontinence, stress incontinence.
incubator an apparatus with controlled temperature and oxygen concentration used for preterm or sick babies. A low-temperature oven in which bacteria are cultured.
incus anvil-shaped bone of the middle ear. See also malleus, stapes.
independent variable the variable conditions of an experimental situation, e.g. control or experimental.
indicator a substance used to make visible the completion of a chemical reaction or the achievement of a certain pH.
indicator lamps situated on a control panel to give the status of equipment, for example, if the door of the treatment room is closed, or outside the room to indicate treatment is in progress.
indigenous of a disease, etc., native to a certain locality or country.
indigestion (dyspepsia) a feeling of gastric discomfort, including fullness and gaseous distension, which is not necessarily a manifestation of disease.
indirect cost a cost that cannot be attributed to any one department and its budget. It is shared between various budgets, for example, the cost of heating a building.
indolent slow growing, reluctant to heal.
induction the production of an electromotive force in a conductor when it is moving relative to a magnetic field of changing intensity. The act of bringing on or causing to occur, as applied to anaesthesia and labour.
induration the hardening of tissue, as in hyperaemia, infiltration by tumour, etc.
industrial dermatitis a term used in the National Insurance (Industrial Injuries) Act to cover occupational skin conditions.
industrial disease (occupational disease) a disease contracted by reason of occupational exposure to an industrial agent known to be hazardous, for example, dust, fumes, chemicals, irradiation, etc., the notification of, safety precautions against and compensation for which are controlled by law.
inelastic collisions the mutual attraction of atoms, molecules, etc. when either the energy from one particle is given to the other or only kinetic, excitation or ionization energy is transferred after the collision.
inevitable abortion miscarriage.
inevitable miscarriage loss of the pregnancy cannot be prevented.
in extremis at the point of death.
infant a child of less than 1 year old.
infarct area of tissue affected when the end artery supplying it is occluded by atheroma, thrombosis or embolism, for example, in myocardium or lung.
infarction irreversible premature tissue death. Necrosis (death) of a section of tissue because the blood supply has been cut off. See also myocardial infarction, pulmonary infarction.
infection the successful invasion, establishment and growth of micro-organisms in body tissues. It may be acute or chronic. See also autoinfection, cross infection, hospital-acquired infection, opportunistic infection.
infectious disease a disease caused by a specific, pathogenic microorganism and capable of transmission to another individual by direct or indirect contact.
infective infectious. Disease transmissible from one host to another.
inferential statistics also known as inductive statistics. That which uses the observations of a sample to make a prediction about other samples, i.e. makes generalizations from the sample. See also descriptive statistics.
