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Glossary of terms

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All 

See cardiac pacemaker.

A measure of an individual's cigarette smoking history calculated by multiplying the number of cigarette packs smoked per day by the number of years the individual has smoked.

Paget disease
A genetic or viral condition characterized by excessive breakdown and formation of bone tissue that can lead to enlarged or misshapen bones.

palliative treatment
Treatment designed to relieve or control symptoms rather than to cure disease.


  1. Able to be felt; perceptible to touch
  2. Evident; plain

A gland that produces several hormones and secretes digestive enzymes, or proteins that act as a catalyst for the breakdown of food, through the pancreatic duct that connects the gland to the intestine. The pancreas also secretes hormones, most importantly insulin, into the blood to regulate metabolism of the body.

pancreatic duct
A tubular passageway that connects the pancreas to the intestine.

Inflammation (swelling) of the pancreas.

An imaging examination of the pancreatic ducts. For x-ray pancreatography, the examination requires direct injection of contrast material into the pancreatic ducts. For MRI, pancreatography is performed without a direct contrast material injection, however an intravenous injection of contrast material may be used.

Pap test
Also known as Pap smear.
The removal of cells from the surface or interior of a woman’s cervix for examination under a microscope; used to help detect cervical cancer.

A tumor, usually benign, that may appear on a mucous membrane or the surface of the skin.

A minimally invasive procedure in which a thin needle or tube is inserted into the abdomen to remove excess fluid from the peritoneal cavity.

Alongside the nose.

paranasal sinuses
Four pairs of hollow, air-filled spaces located within the bones of the face that surround the nasal cavity and are connected to the nose by small openings. They are named the frontal, maxillary, ethmoid, and sphenoid sinuses.

parathyroid glands
Typically four small raisin-sized glands in the neck primarily involved in the regulation of calcium and phosphorus levels in the body.

parathyroid imaging
Evaluation of the parathyroid glands, accomplished with a nuclear medicine technique using a material called Sestamibi, or the parathyroid glands can be imaged with ultrasound, CT or MRI.

partial bowel resection
See partial colectomy.

partial colectomy
Removal of part of the colon.

particle beam radiation therapy
Particle or proton beam radiation therapy is a type of radiation therapy that uses protons as the source of radiation rather than x-rays. Protons can pass through healthy tissue without damaging it. See the Proton Therapy page for more information.

particulate agents
Synthetic materials that are suspended in liquid and injected into a blood vessel to form a permanent barrier to blood flow. They are used in embolization procedures to stop bleeding or block arteries that provide blood flow to a tumor.

The state of being freely open or exposed.

Morbid or diseased; resulting from disease.

A physician specializing in the examination of cells and tissues.

The study of disease processes.

pelvic floor dysfunction
(Also called pelvic floor disorders).
A group of conditions in which the stretching or tearing of the pelvic floor leads to one or more of the pelvic organs falling out of position (also called prolapse), incontinence, pelvic pain and/or constipation.

penetrating injury
An injury in which the skin is broken as the result of a cut (laceration).

A passing through the skin, as in absorption of an ointment containing the active ingredient; also passage through the skin by needle puncture, including introduction of wires and catheters.

percutaneous transhepatic cholangiography (PTC)
An x-ray procedure that involves the injection of a contrast material directly into the liver to produce pictures of the bile ducts.

A hole in the walls of an organ or structure of the body that develops from a weak spot in the organ or from a deep penetrating wound caused by trauma.

The flow of blood or other fluid to an organ.

pericardial effusion
Excessive fluid within the sac surrounding the heart, usually due to inflammation.

The surface of the body between the anus and the scrotum in men and between the anus and the vulva in women.

periodontal disease
Disease that affects the tissue and bone surrounding the teeth.

peripheral artery disease (PAD)
Also called peripheral vascular disease (PVD).
Arterial disease that occurs outside of the heart or brain in which arteries in the extremities (legs and arms) become narrowed or blocked, usually as a result of atherosclerosis or plaque. The most common form of PAD affects the large vessels supplying the legs, which can cause severe pain on walking and may in time make a patient immobile. See the Peripheral Artery Disease page for more information.

peripheral vascular disease (PVD)
See peripheral artery disease (PAD)..

peripherally inserted central catheter (PICC)
A long catheter that extends from an arm or leg vein into the largest vein (superior vena cava or inferior vena cava) near the heart and typically provides central IV access for several weeks. Unlike a standard intravenous catheter (IV) which is for short term use, a PICC is more durable and does not easily become blocked or infected. It may remain in place for several months so that blood can be repeatedly drawn or medication and nutrients can be routinely injected into the patient’s bloodstream.

peritoneal cavity
Also called abdominal cavity.
The space within the peritoneum not occupied by the abdominal organs. In most circumstances, this space is empty and the cavity is collapsed. In certain disease, this space can become filled with fluid. In other circumstances, this space may be intentionally inflated with carbon dioxide for laparoscopic surgery, or with a sterile solution for peritoneal dialysis.

peritoneal port
A small reservoir or chamber about the size of a quarter that is surgically implanted under the skin near the abdomen. The port has a silicone rubber top that can be penetrated by a needle and an attached catheter that is designed to hang down into the abdominal or peritoneal cavity.

A thin layer of connective tissue that lines the abdominal cavity.

Inflammation of the thin tissues that line the abdomen and the abdominal organs.

periventricular leukomalacia (PVL)
Damage to white matter brain tissue as a result of a lack of oxygen or blood flow to the brain prior, during or after birth.

permanent brachytherapy
Also called seed implantation.
A radiation therapy treatment for cancer in which a sealed pellet (or “seed”) containing radioactive material is permanently placed inside the body in or near a tumor.

Also known as hydrogen peroxide, a liquid bleaching agent used as a disinfectant.

petit mal seizure
Also called an absence seizure.
A type of seizure or convulsion often associated with epilepsy in which the patient stares into space for a short period of time.

Related to the pharynx, or throat.

Also known as the throat, the passageway that extends from immediately behind the mouth and nasal cavity to the esophagus and stomach.

Removal of a vein segment, sometimes performed for the treatment of varicose veins.

Painful inflammation (swelling) of the veins.

photodynamic therapy
A form of treatment in which a drug is administered and then activated by light.

photon radiation therapy
See cobalt-60 radiation therapy.

A specialist in the science of physics.

Picture Archiving and Communication System (PACS)
A computer system for acquiring, storing, viewing, and managing digital medical imaging studies and related information.

pituitary adenoma
A common, benign tumor of the pituitary gland that may affect hormonal levels.

pituitary gland
An endocrine gland located beneath the brain that supplies numerous hormones that govern many vital processes in the body.

An accumulation of fat and other substances on the inner wall of a blood vessel that, over time, may build up and limit or block blood flow through the vessel.

Particles that are formed in bone marrow and circulate in the blood. They bind at the site of a wound to begin the clotting process.

platinum coils
A type of coil, made of soft platinum wire smaller than a strand of hair, used in a procedure called a detachable coil embolization to treat an aneurysm or an artificial blood vessel connection called a fistula that may occur in the brain or other parts of the body. Using imaging guidance, the coils are placed at the site of an aneurysm or fistula to help block the flow of blood or prevent a rupture of the vessel.

A brand name for clopidogrel, an antiplatelet drug prescribed to help prevent blood clots.

pleural effusion
An excess of fluid in the pleural cavity, the space that surrounds the lungs and lies underneath the chest wall.

pleural membrane
A thin layer of tissue that lines the pleural cavity, the space that surrounds the lungs and lies underneath the chest wall.

pleural space
Also called pleural cavity.
The cavity that exists between the lungs and underneath the chest wall. It is normally empty, with the lung immediately against the inside of the chest wall. In some diseases, fluid can build up in this space (a pleural effusion). In trauma, air can enter this space (a pneumothorax). Under either condition, excessive fluid or air in the pleural space can cause difficulty breathing since the lung is prevented from inflating fully.

Inflammation of the membrame encasing the lungs.

An infection that causes inflammation in one or both of the lungs; may be caused by a virus, bacteria, fungi or other germs. See the Pneumonia page for more information.

A condition in which air enters and collects within in the pleural space and may cause the lung to collapse. It occurs during heart or lung surgery or as a result of a trauma (such as a gunshot or stab wound) to the chest, but also may occur spontaneously, particularly with violent coughing.

A condition in which air enters and collects within in the pleural space and may cause the lung to collapse. It occurs during heart or lung surgery or as a result of a trauma (such as a gunshot or stab wound) to the chest, but also may occur spontaneously, particularly with violent coughing.

A disorder in which there is an abnormal increase in the number of red blood cells in the blood.

polymethylmethacrylate (PMMA)
An acrylic cement used to repair bone fractures and in other orthopedic procedures.

A usually benign growth that bulges outward from the surface of normal tissue, usually appearing as an irregular mound- or mushroom-like structure growing from a broad base or a slender stalk.

A procedure using an endoscope in which abnormal growths called polyps are removed from the inner walls of the colon and rectum.

Having small holes or pores.

portal hypertension
Blockage of normal blood flow through the liver, usually the result of cirrhosis, which can lead to back-pressure on the veins of the portal (intestinal) circulation, variceal bleeding and ascites.

portal vein
Also called the hepatic portal vein.
The main vein that carries blood from the digestive tract to the liver.

Manufacturer's name. See implanted port.

Imaging of the portal circulation by x-rays, using contrast material, usually introduced into the spleen or into the portal vein at operation.

positron emission tomography (PET)
Positron emission tomography, also called PET or a PET scan, is a diagnostic examination that uses small amounts of radioactive materials called radiotracers, a special camera and a computer to help evaluate your organ and tissue functions. By identifying body changes at the cellular level, PET may detect the early onset of disease before it is evident on other imaging tests. See the PET/CT page for additional information.

post-embolization syndrome
A condition that includes pain, nausea, vomiting and low-grade fever that many patients experience following an embolization procedure. to prevent blood from flowing to the area.

posteroanterior view
A term typically denoting the direction of x-rays, from posterior to anterior, through a body part.

power Doppler
An ultrasound technique that is used to obtain images that are difficult or impossible to obtain using standard color Doppler and to provide greater detail of blood flow, especially in vessels that are located inside organs. Power Doppler is more sensitive than color Doppler for the detection and demonstration of blood flow, but provides no information about the direction of flow. Color and spectral Doppler both reveal the direction of blood flow which can be valuable information.

Abnormal tissue changes that often are found before cancer develops.

primary aldosteronism
A condition in which the adrenal glands produce too much of the hormone aldosterone, leading to high blood pressure.

primary headache
One of the two major types of headaches. Primary headaches, which include cluster, migraine and tension headaches, are not associated with a medical condition or disease.

primary tumor
A tumor that originates at its location. See also tumor.


  1. A slender rod of flexible material, with blunt bulbous tip, used for exploring sinuses, fistulas, other cavities, or wounds.
  2. A device or agent used to detect or explore a substance; e.g., a molecule used to detect the presence of a specific fragment of DNA or RNA or of a specific bacterial colony.
  3. To enter and explore, as with a probe.

A surgical procedure to remove the rectum and part or the entire colon.

This procedure uses a special camera at the end of a tube that allows the doctor to see inside the rectum.

Related to a medical prognosis, a prediction of the course and likely outcome of a disease.

prophylactic cranial radiation
Exposure of the brain to low-dose radiation in a cancer patient in order to prevent the tumor from spreading to this site.

prostate cancer
A tumor of the prostate gland, which is located in front of a man's rectum and below the bladder.

prostate gland
A walnut-size gland in men that surrounds the urethra (the duct that transports urine out of the body) and the base of the bladder. The prostate, part of the male reproductive system, makes some of the milky fluid called semen that carries sperm.

prostate-specific antigen (PSA)
A protein produced by the prostate gland. A PSA Test is used to determine the level of PSA in the blood. Higher levels of PSA in the blood are sometimes – but not always – indicative of prostate cancer.

An inflammation (swelling) of the prostate gland.

protected health information (PHI)

Any information relating to a patient's physical or mental health, the details of one's care, or the payment for that health care. The U.S. Department of Health and Human Services (HHS) defines all of the following as individually identifiable health information:

  1. Names and addresses
  2. Identifying Dates – date of birth, date of admission, date of examination.
  3. Specific age if over 89 years old.
  4. Telephone and fax numbers, Social Security numbers, medical record or account numbers, employee numbers, health plan numbers, email addresses, vehicle identifiers, license numbers.
  5. Full face images or biometric identifiers such as finger and/or voice prints.
  6. Any unique identification numbers, codes or characteristics that may be traced back to an individual.

A positively charged particle that is a fundamental component of the nucleus of all atoms.

proton beam radiation therapy
See particle beam radiation therapy.

Related to the lungs or the respiratory system.

pulmonary edema
A build-up of fluid in the lungs and a swelling of lung tissue.

pulmonary embolism
Blockage of the arteries in the lungs, most frequently by detached fragments of a blood clot from a leg or pelvic vein, commonly when that clot follows an operation or confinement to bed.

pulmonary hypertension
A type of high blood pressure within the network of blood vessels between the heart and lungs.

A physician who specializes in pulmonology (pulmonary disease), which deals with lung and respiratory tract disease.

pulse oximetry
A test that involves a small device placed on a finger tip to measure the oxygen saturation of the blood.

Radiologic study of the kidney, ureters, and usually the bladder, performed with the aid of a contrast material either injected intravenously, or directly from below via the urethra, or from above through the kidney (either via a direct puncture or through a previously placed catheter).

A bacterial infection of the kidney that may occur when a urinary tract infection (UTI) spreads beyond the bladder to the ureters and kidneys.

The passage from the stomach into the small intestines.