Boils and carbuncles are bacterial infections of hair follicles and surrounding skin that form pustules (small blister-like swellings containing pus) around the follicle. Boils are sometimes called furuncles. A carbuncle is formed when several furuncles merge to form a single deep abscess with several heads or drainage points. Boils and carbuncles are firm reddish swellings about0.2-0.4 in (5-10 m…
Bone biopsy is the removal of a piece of bone for laboratory examination and analysis. Bone biopsy is used to distinguish between malignant tumors and benign bone disease such as osteoporosis and osteomyelitis. This test may be ordered to determine why a patient's bones ache or feel sore, or when a mass or deformity is found on an x ray, CT scan, bone scan, or other diagnostic imaging proce…
Computer read-out of a bone density scan. (Photo Researchers. Reproduced by permission.) A bone density test, or scan, is designed to check for osteoporosis, a disease that occurs when the bones become thin and weak. Osteoporosis happens when the bones lose calcium and other minerals that keep them strong. Osteoporosis begins after menopause in many women, and worsens after age 65, often re…
Bone disorder drugs are medicines used to treat diseases that weaken the bones. The drugs described here are used to treat or prevent osteoporosis (brittle bone disease) in women past menopause as well as older men. They also are used prescribed for Paget's disease, a painful condition that weakens and deforms bones, and they are used to control calcium levels in the blood. Bone is living t…
Bone grafting is a surgical procedure by which new bone or a replacement material is placed into spaces between or around broken bone (fractures) or holes in bone (defects) to aid in healing. Bone grafting is used to repair bone fractures that are extremely complex, pose a significant risk to the patient, or fail to heal properly. Bone graft is also used to help fusion between vertebrae, correct d…
Bone growth stimulation is the technique of promoting bone growth in difficult to heal fractures by applying a low electrical current or ultrasound to the fracture. Bone growth stimulation is done when satisfactory healing is not occurring naturally or when the pace of healing is too slow. This condition is called fracture nonunion, and it occurs more frequently among adults than children, in peop…
Bone marrow aspiration, also called bone marrow sampling, is the removal by suction of fluid from the soft, spongy material that lines the inside of most bones. Bone marrow biopsy, or needle biopsy, is the removal of a small piece of bone marrow. Bone marrow aspiration is used to: Bone marrow biopsy is used to: Bone marrow aspiration and bone marrow biopsy are also used to gauge the effectiveness …
The bone marrow—the sponge-like tissue found in the center of certain bones—contains stem cells that are the precursors of white blood cells, red blood cells, and platelets. These blood cells are vital for normal body functions, such as oxygen transport, defense against infection and disease, and clotting. Blood cells have a limited lifespan and are constantly being replaced; therefo…
A bone scan is a diagnostic procedure used to evaluate abnormalities involving bones and joints. A radioactive substance is injected intravenously, and the image of its distribution in the skeletal system is analyzed to detect certain diseases or conditions. Bone scans are most frequently ordered to check whether a cancer that originated elsewhere has spread to the bones. Cancers which begin in th…
Bone x rays are a diagnostic test in which ionizing radiation passing through the bones being examined enables an image to be produced on film. Bone x rays are ordered to detect disease or injury to the bone such as broken bones, tumors, and other problems. They can determine bone density, texture, erosion, and changes in bone relationships. Bone x rays also evaluate the joints for diseases such a…
Botulinum is a bacterium (Clostridium botulinum) that produces seven different toxins that can cause botulism and is also medically used to block muscle contractions. Botulinum toxin (Botox) injection is used in conditions of excessive and inappropriate muscle contraction, hyperhidiosis (excess sweating) in armpits and palms, spasticity (persistent states of muscle contraction), sphincter contract…
Botulism is caused by botulinum toxin, a natural poison produced by certain bacteria in the Clostridium genus. Exposure to the botulinum toxin occurs mostly from eating contaminated food, or in infants, from certain clostridia growing in the intestine. Botulinum toxin blocks motor nerves' ability to release acetylcholine, the neurotransmitter that relays nerve signals to muscles, and flacci…
Bowel preparation is a procedure usually undertaken before a diagnosis and /or treatment can be initiated for certain colon and rectum diseases. Bowel preparation is a cleansing of the intestines from fecal matter and secretions. The ultimate goal of bowel preparation is priming the bowel for a diagnosis procedure (using x rays to detect a disease process in the intestines) or for surgical interve…
A bowel resection is a surgical procedure in which a part of the large or small intestine is removed. Bowel resection may be performed to treat various disorders of the intestine, including cancer, obstruction, inflammatory bowel disease, ruptured diverticulum, ischemia (compromised blood supply), or traumatic injury. The preferred type of bowel resection involves removal of the diseased portion o…
Bowel training helps to reestablish normal bowel movements in persons who suffer from constipation, diarrhea, incontinence, or irregularity. Healthy bowel activity is considered one or two movements of moderate size every day. Many people for many reasons have irregular bowel function. In some cases, the irregularity lasts beyond the condition that caused it. The bowels by themselves develop bad h…
Brain abscess is a bacterial infection within the brain. The brain is usually well insulated from infection by bacteria, protected by the skull, the meninges (tissue layers surrounding the brain), the immune system, and the highly regulated barrier between the bloodstream and the brain. Under certain circumstances, however, bacteria can invade the brain and cause a localized infection called an ab…
A brain biopsy is the removal of a small piece of brain tissue for the diagnosis of abnormalities of the brain, such as Alzheimer's disease, tumors, infection, or inflammation. By examining the tissue sample under a microscope, the biopsy sample provides doctors with the information necessary to guide diagnosis and treatment. Imaging of the brain is performed to determine the precise positi…
A brain tumor is an abnormal growth of tissue in the brain. Unlike other tumors, brain tumors spread by local extension and rarely metastasize (spread) outside the brain. A benign brain tumor is composed of non-cancerous cells and does not metastasize beyond the part of the brain where it originates. A brain tumor is considered malignant if it contains cancer cells, or if it is composed of harmles…
A breast biopsy is removal of breast tissue for examination by a pathologist. This can be accomplished surgically, or by withdrawing tissue through a needle. A biopsy is recommended when a significant abnormality is found, either on physical examination and/or by an imaging test. Examples of abnormality can include a breast lump felt during physical self examination or tissue changes noticed from …
Breast cancer is caused by the development of malignant cells in the breast. The malignant cells originate in the lining of the milk glands or ducts of the breast (ductal epithelium), defining this malignancy as a cancer. Cancer cells are characterized by uncontrolled division leading to abnormal growth and the ability of these cells to invade normal tissue locally or to spread throughout the body…
Breast implantation is a surgical procedure for enlarging the breast. Breast-shaped sacks made of a silicone outer shell and filled with silicone gel or saline (salt water), called implants, are used. Breast implantation is usually performed to make normal breasts larger for cosmetic purposes. Sometimes a woman having a breast reconstruction after a mastectomy will need the opposite breast enlarge…
Breast reconstruction is a series of surgical procedures performed to recreate a breast. Reconstructions are commonly done after one or both breasts are removed as a treatment for breast cancer. Also, a breast may need to be refashioned for other reasons, such as trauma or abnormalities that occur during breast development. Many authorities consider reconstruction an integral part of the therapy f…
Breast reduction is a surgical procedure performed in order to decrease the size of the breasts. Women with very large breasts (macromastia or mammary hyperplasia) seek breast reduction for relief of pain in the back, shoulder, and neck. They may also feel uncomfortable about their breast size and have difficulty finding clothing that will fit properly. Additionally, breast reduction may be needed…
A breast self-examination (BSE) is an inspection by a woman of her breasts to detect breast cancer. A BSE is one of three tests the American Cancer Society recommends to help detect breast cancer in its earliest stages. By regularly examining her own breasts, a woman is more likely to find any changes that may have occurred. The best time to perform a BSE is about a week after a woman's per…
Breast ultrasound (or sonography) is an imaging technique for diagnosing breast disease, such as cancer. It uses harmless, high frequency sound waves to form an image (sonogram). The sound waves pass through the breast and bounce back or echo from various tissues to form a picture of the internal structures. It is not invasive and involves no radiation. Breast ultrasound may be used in several way…
Breech birth is the delivery of a fetus (unborn baby) hind end first. Between 3-4% of fetuses will start labor in the breech position, which is a potentially dangerous situation. Throughout most of pregnancy, the developing fetus is completely free to move around within the uterus. Between 32-36 weeks, it becomes so large that movement is restricted. It is much harder for the fetus to turn over, s…
Bronchiectasis is a condition in which an area of the bronchial tubes is permanently and abnormally widened (dilated), with accompanying infection. The bronchial tubes are the networks of branching tubes which deliver air to the tiny sacs of the lungs (alveoli). In bronchiectasis, the diameter of the bronchi is unusually large. Examination of the walls of the bronchial tubes reveals destruction of…
Bronchitis is an inflammation of the air passages between the nose and the lungs, including the windpipe or trachea and the larger air tubes of the lung that bring air in from the trachea (bronchi). Bronchitis can either be of brief duration (acute) or have a long course (chronic). Acute bronchitis is usually caused by a viral infection, but can also be caused by a bacterial infection and can heal…
Bronchodilators are medicines that help open the bronchial tubes (airways) of the lungs, allowing more air to flow through them. People with asthma have trouble breathing, because their airways are inflamed and become narrowed. Normally, air moves smoothly from the mouth and nose through the airways and into the tiny air sacs of the lungs as a person breathes in. Breathing out (exhaling) happens a…
Bronchoscopy is a procedure in which a cylindrical fiberoptic scope is inserted into the airways. This scope contains a viewing device that allows the visual examination of the lower airways. During a bronchoscopy, a physician can visually examine the lower airways, including the larynx, trachea, bronchi, and bronchioles. The procedure is used to examine the mucosal surface of the airways for abno…
Brucellosis is a bacterial disease caused by members of the Brucella genus that can infect humans but primarily infects livestock. Symptoms of the disease include intermittent fever, sweating, chills, aches, and mental depression. The disease can become chronic and recur, particularly if untreated. Also known as undulant fever, Malta fever, Gibraltar fever, Bang's disease, or Mediterranean …
Bruises, or ecchymoses, are a discoloration and tenderness of the skin or mucous membranes due to the leakage of blood from an injured blood vessel into the tissues. Pupura refers to bruising as the result of a disease condition. A very small bruise is called a petechia. These often appear as many tiny red dots clustered together, and could indicate a serious problem. Bruises change colors over ti…
Bruxism is the habit of clenching and grinding the teeth. It most often occurs at night during sleep, but it may also occur during the day. It is an unconscious behavior, perhaps performed to release anxiety, aggression, or anger. Bruxism is one of the oldest disorders known, and approximately one in four adults experiences it. Most people are not aware of it before their teeth have been damaged. …
Budd-Chiari syndrome is a rare problem that results from blood clotting in the veins flowing out of the liver (hepatic veins). The high pressure of blood in these veins leads to an enlarged liver, and to an accumulation of fluid in the abdomen, called ascites. The liver, the largest internal organ in the human body, is responsible for many vital physiologic processes. Blood flow through the liver …
Buerger's disease is an inflammation of the arteries, veins, and nerves in the legs, principally, leading to restricted blood flow. Left untreated, Buerger's disease can lead to gangrene of the affected areas. Buerger's disease is also known as thromboangitis obliterans. The exact cause of Buerger's disease is not known. It is seen most often in young to middle-aged men…
Bulimia nervosa is a serious and sometimes life-threatening eating disorder affecting mainly young women. People with bulimia, known as bulimics, consume large amounts of food (binge) and then try to rid themselves of the food and calories (purge) by fasting, excessive exercise, vomiting, or using laxatives. The behavior often serves to reduce stress and relieve anxiety. Because bulimia results fr…
Bundle branch block (BBB) is a disruption in the normal flow of electrical pulses that drive the heart beat. Bundle branch block belongs to a group of heart problems called intraventricular conduction defects (IVCD). There are two bundle branches, right and left. The right bundle carries nerve impulses that cause contraction of the right ventricle (the lower chamber of the heart) and the left bund…
A bunion is an abnormal enlargement of the joint (the first metatarsophalangeal joint, or MTPJ) at the base of the great or big toe (hallux). It is caused by inflammation and usually results from chronic irritation and pressure from poorly fitting footwear. A displacement of two major bones of the foot (hallux valgus) causes bunions, although not everyone with this displacement will develop the jo…
Burns are injuries to tissues caused by heat, friction, electricity, radiation, or chemicals. Burns are characterized by degree, based on the severity of the tissue damage. A first-degree burn causes There are three classifications of burns: first-degree, second-degree, and third-degree burns. (Illustration by Electronic Illustrators Group.) redness and swelling in the outermost layers of s…
Bursitis is the painful inflammation of the bursa, a padlike sac found in areas subject to friction. Bursae cushion the movement between the bones, tendons and muscles near the joints. Bursitis is most often caused by repetitive movement and is known by several common names including weaver's bottom, clergyman's knee, and miner's elbow, depending on the affected individual�…
Byssinosis is a chronic, asthma-like narrowing of the airways. Also called brown lung disease, byssinosis results from inhaling particles of cotton, flax, hemp, or jute. Although inhaling cotton dust was identified as a source of respiratory disease more than 300 years ago, byssinosis has been recognized as an occupational hazard for textile workers for less than 50 years. More than 800,000 worker…
Caffeine is a drug that stimulates the central nervous system. Caffeine makes people more alert, less drowsy, and improves coordination. Combined with certain pain relievers or medicines for treating migraine headache, caffeine makes those drugs work more quickly and effectively. Caffeine alone can also help relieve headaches. Antihistamines are sometimes combined with caffeine to counteract the d…
Calcium channel blockers are medicines that slow the movement of calcium into the cells of the heart and blood vessels. This, in turn, relaxes blood vessels, increases the supply of oxygen-rich blood to the heart, and reduces the heart's workload. Calcium channel blockers are used to treat high blood pressure, to correct abnormal heart rhythms, and to relieve the type of chest pain called a…
Campylobacteriosis refers to infection by the group of bacteria known as Campylobacter. The term comes from the Greek word meaning "curved rod" referring to the bacteria's curved shape. The most common disease caused by these organisms is diarrhea, which most often affects children and younger adults. Campylobacter infections account for a substantial percent of food-borne ill…
Cancer is not just one disease, but a large group of almost one hundred diseases. Its two main characteristics are uncontrolled growth of the cells in the human body and the ability of these cells to migrate from the original site and spread to distant sites. If the spread is not controlled, cancer can result in death. One out of every four deaths in the United States is from cancer. It is second …
Definitive cancer therapy is a treatment plan designed to potentially cure cancer using one or a combination of interventions including surgery, radiation, chemical agents, or biological therapies. The primary purpose of definitive care is to establish a cure and to destruct and remove all cancer cells from the infected person. Surgery is not only a diagnostic tool, but also used for tumor removal…
Palliative cancer therapy is treatment specifically directed to help improve the symptoms associated with terminal cancer. Palliative care is directed to improving symptoms associated with incurable cancer. Care can include surgery, radiation therapy, chemotherapy, symptomatic treatments resulting from cancer, and side effects of treatment. The primary objective of palliative care is to improve th…
Supportive cancer therapy is the use of medicines to counteract unwanted effects of cancer treatment. Along with their beneficial effects, many cancer treatments produce uncomfortable and sometimes harmful side effects. For example, cancer drugs may cause nausea or vomiting. They may also destroy red or white blood cells, resulting in a low blood count. Fortunately, many of these side effects can …
Candidiasis is an infection caused by a species of the yeast Candida, usually Candida albicans. This is a common cause of vaginal infections in women. Also, Candida may cause mouth infections in people with reduced immune function, or in patients taking certain antibiotics. Candida can be found in virtually all normal people but causes problems in only a fraction. In recent years, however, several…
Canker sores are small sores or ulcers that appear inside the mouth. They are painful, self-healing, and can recur. Canker sores occur on the inside of the mouth, usually on the inside of the lips, cheeks, and/or soft palate. They can also occur on the tongue and in the throat. Often, several canker sores will appear at the same time and may be grouped in clusters. Canker sores appear as a whitish…
Carbohydrate intolerance is the inability of the body to completely process the nutrient carbohydrate (a classification that includes sugars and starches) into a source of energy for the body, usually because of the deficiency of an enzyme needed for digestion. Lactose intolerance, the inability to digest the sugar found in milk, is widespread and affects up to 70% of the world's adult popu…
Carbon monoxide (CO) poisoning occurs when carbon monoxide gas is inhaled. CO is a colorless, odorless, highly poisonous gas that is produced by incomplete combustion. It is found in automobile exhaust fumes, faulty stoves and heating systems, fires, and cigarette smoke. Other sources include woodburning stoves, kerosene heaters, improperly ventilated water heaters and gas stoves, and blocked or p…
The carcinoembryonic antigen (CEA) test is a laboratory blood study. CEA is a substance which is normally found only during fetal development, but may reappear in adults who develop certain types of cancer. The CEA test is ordered for patients with known cancers. The CEA test is most commonly ordered when a patient has a cancer of the gastrointestinal system. These include cancer of the colon, rec…
A cardiac blood pool scan is a non-invasive test that uses a mildly radioactive marker to observe the functioning of the left ventricle of the heart. The left ventricle is the main pump for distributing blood through the body. A cardiac blood pool scan is used to determine how efficiently the left ventricle is working. The scan can detect aneurysms of the left ventricle, motion abnormalities cause…
Cardiac catheterization (also called heart catheterization) is a diagnostic procedure which does a comprehensive examination of how the heart and its blood vessels function. One or more catheters is inserted through a peripheral blood vessel in the arm (antecubital artery or vein) or leg (femoral artery or vein) with x-ray guidance. This procedure gathers information such as adequacy of blood supp…
Cardiac rehabilitation is a comprehensive exercise, education, and behavioral modification program designed to improve the physical and emotional condition of patients with heart disease. Heart attack survivors, bypass and angioplasty patients, and individuals with angina, congestive heart failure, and heart transplants are all candidates for a cardiac rehabilitation program. Cardiac rehabilitatio…
Cardiac tamponade occurs when the heart is squeezed by fluid that collects inside the sac that surrounds it. The heart is surrounded by a sac called the pericardium. When this sac becomes filled with fluid, the liquid presses on the heart, preventing the lower chambers of the heart from properly filling with blood. Because the lower chambers (the ventricles) cannot fill with the correct amount of …
Cardiopulmonary resuscitation (CPR) is a procedure to support and maintain breathing and circulation for a person who has stopped breathing (respiratory arrest) and/or whose heart has stopped (cardiac arrest). CPR is performed to restore and maintain breathing and circulation and to provide oxygen and blood flow to the heart, brain, and other vital organs. CPR should be performed if a person is un…
Cardioversion refers to the process of restoring the heart's normal rhythm by applying a controlled electric shock to the exterior of the chest. When the heart beats too fast, blood no longer circulates effectively in the body. Cardioversion is used to stop this abnormal beating so that the heart can begin normal rhythm and pump more efficiently. Not all unusual heart rhythms (called arrhyt…
Computed tomography (CT) is a process that images anatomic information from a cross-sectional plane of the body. Biopsy is the process of taking a sample of tissue from the body for analysis. CT is commonly used in biopsies to provide images that help guide the tools or equipment necessary to perform the biopsy to the appropriate area of the body. CT is used in the process of performing a biopsy, …
2,3-diphosphoglycerate (2,3-DPG) is a substance made in the red blood cells. It controls the movement of oxygen from red blood cells to body tissues. 2,3-DPG testing is done to help investigate both a deficiency in red blood cells (anemia) and an unexplained increase of red blood cells, called erythrocytosis. Hemoglobin, the protein in the blood that carries oxygen, uses 2,3-DPG to control how muc…
