The surgical removal of the foreskin of the penis or prepuce. In the United States, circumcision in infant boys is performed for social, medical, or cultural/religious reasons. Once a routine operation urged by pediatricians and obstetricians for newborns in the middle of the twentieth century, circumcision has become an elective option that parents make for their sons on an individual basis. Fami…
Cirrhosis is a chronic, degenerative disease in which normal liver cells are damaged and are then replaced by scar tissue. Cirrhosis changes the structure of the liver and the blood vessels that nourish it. The disease reduces the liver's ability to manufacture proteins and process hormones, nutrients, medications, and poisons. Cirrhosis gets worse over time and can become potentially life …
A cleft is a birth defect that occurs when the tissues of the lip and/or palate of the fetus do not fuse very early in pregnancy. A cleft lip, sometimes referred to as a harelip, is an opening in the upper lip that can extend into the base of the nostril. A cleft palate is an opening in the roof of the mouth. Babies born with cleft lips will have an opening involving the upper lip. The length of t…
A clenched fist injury (CFI) is a bite wound on the hand, caused when a person's closed fist strikes the teeth of another person, usually in the course of a fight. CFIs are sometimes referred to as closed fist injuries or fight bites. Clenched fist injuries are most common over the metacarpo phalangeal joint. Their appearance is deceptive because they do not bleed heavily and the underlying…
Clubfoot is a condition in which one or both feet are twisted into an abnormal position at birth. The condition is also known as talipes. True clubfoot is characterized by abnormal bone formation in the foot. There are four variations of clubfoot, including talipes varus, talipes valgus, talipes equines, and talipes calcaneus. In talipes varus, the most common form of clubfoot, the foot generally …
Cluster headaches are characterized by an intense one-sided pain centered by the eye or temple. The pain lasts for one to two hours on average and may recur several times in a day. Cluster headaches have been known as histamine headaches, red migraines, and Horton's disease, among others. The constant factor is the pain, which transcends by far the distress of the more common tension-type h…
Coagulation disorders deal with disruption of the body's ability to control blood clotting. The most commonly known coagulation disorder is hemophilia, a condition in which patients bleed for long periods of time before clotting. There are other coagulation disorders with a variety of causes. Coagulation, or clotting, occurs as a complex process involving several components of the blood. Pl…
A defect that develops in the fetus in which there is a narrowing of the aortic arch, the main blood artery that delivers blood from the left ventricle of the heart to the rest of the body. Coarctation of the aorta is diagnosed in both newborns and adults. Approximately 10% of newborns with congenital heart disease have coarctation of the aorta. Blood leaves the heart by way of the left ventricle …
Cocaine is a highly addictive central nervous system stimulant extracted from the leaves of the coca plant, Erythroxylon coca. In its most common form, cocaine is a whitish crystalline powder that produces feelings of euphoria when ingested. Now classified as a Schedule II drug, cocaine has legitimate medical uses as well as a long history of recreational abuse. Administered by a licensed physicia…
Coccidioidomycosis is an infection caused by inhaling the microscopic spores of the fungus Coccidioides immitis. Spores are the tiny, thick-walled structures that fungi use to reproduce. Coccidioidomycosis exists in three forms. The acute form produces flu-like symptoms. The chronic form can develop as many as 20 years after initial infection and, in the lungs, can produce inflamed, injured areas …
The coccyx—or tailbone—is the last bone of the vertebral column, and usually consists of three to five fused vertebrae that connect with the sacrum, a part of the pelvis. The coccyx consists of fused vertebrae, which are not flexible like the other vertebrae of the vertebral column which are all interspaced by intervertebral disks and joined together by elastic ligaments. Since the s…
A cochlear implant is a surgical treatment for hearing loss that works like an artificial human cochlea in the inner ear, helping to send sound from the ear to the brain. It is different from a hearing aid, which simply amplifies sound. A cochlear implant bypasses damaged hair cells and helps establish some degree of hearing by stimulating the hearing (auditory) nerve directly. A close-up view…
Cognitive-behavioral therapy is an action-oriented form of psychosocial therapy that assumes that maladaptive, or faulty, thinking patterns cause maladaptive behavior and "negative" emotions. (Maladaptive behavior is behavior that is counter-productive or interferes with everyday living.) The treatment focuses on changing an individual's thoughts (cognitive patterns) in order …
The cold agglutinins test is performed to detect the presence of antibodies in blood that are sensitive to temperature changes. Antibodies are proteins produced by the immune system in response to specific disease agents; autoantibodies are antibodies that the body produces against one of its own substances. Cold agglutinins are autoantibodies that cause red blood cells to clump, but only when the…
A cold sore is a fluid-filled blister which usually appears at the edge of the lips. Cold sores are caused by a herpes simplex virus infection. A cold sore is a fluid-filled, painful blister that is usually on or around the lips. Other names for a cold sore are fever blister, oral herpes, labial herpes, herpes labialis, and herpes febrilis. Cold sores most often occur on the lips which distinguish…
Colic is persistent, unexplained crying in a healthy baby between two weeks and five months of age. Colic, which is not a disease, affects 10–20% of all infants. It is more common in boys than in girls and most common in a family's first child. Symptoms of colic usually appear when a baby is 14–21 days old, reach a crescendo at the age of three months, and disappear within the…
Cancer of the colon is the disease characterized by the development of malignant cells in the lining or epithelium of the first and longest portion of the large intestine. Malignant cells have lost normal control mechanisms governing growth. These cells may invade surrounding local tissue, or they may spread throughout the body and invade other organ systems. Synonyms for the colon include the lar…
Colonic irrigation is also known as hydrotherapy of the colon, high colonic, entero-lavage, or simply colonic. It is the process of cleansing the colon by passing several gallons of water through it with the use of special equipment. It is similar to an enema but treats the whole colon, not just the lower bowel. This has the effect of flushing out impacted fecal matter, toxins, mucous, and even pa…
Colonoscopy is a medical procedure where a long, flexible, tubular instrument called the colonoscope is used to view the entire inner lining of the colon (large intestine) and the rectum. A colonoscopy is generally recommended when the patient complains of rectal bleeding or has a change in bowel habits and other unexplained abdominal symptoms. The test is frequently used to test for colorectal ca…
Color blindness is an abnormal condition characterized by the inability to clearly distinguish different colors of the spectrum. The difficulties can be mild to severe. It is a misleading term because people with color blindness are not blind. Rather, they tend to see colors in a limited range of hues; a rare few may not see colors at all. Normal color vision requires the use of specialized recept…
Ostomy is a surgical procedure used to create an opening for urine and feces to be released from the body. Colostomy refers to a surgical procedure where a portion of the large intestine is brought through the abdominal wall to carry stool out of the body. A colostomy is created as a means to treat various disorders of the large intestine, including cancer, obstruction, inflammatory bowel disease,…
Colposcopy is a procedure that allows a physician to take a closer look at a woman's cervix and vagina using a special instrument called a colposcope. It is used to check for precancerous or abnormal areas. The colposcope can magnify the area between 10 and 40 times; some devices also can take photographs. The colposcope helps to identify abnormal areas of the cervix or vagina so that small…
Coma, from the Greek word "koma," meaning deep sleep, is a state of extreme unresponsiveness, in which an individual exhibits no voluntary movement or behavior. Furthermore, in a deep coma, even painful stimuli (actions which, when performed on a healthy individual, result in reactions) are unable to affect any response, and normal reflexes may be lost. Coma lies on a spectrum with o…
The common cold is a viral infection of the upper respiratory system, including the nose, throat, sinuses, eustachian tubes, trachea, larynx, and bronchial tubes. Although over 200 different viruses can cause a cold, 30–50% are caused by a group known as rhinoviruses. Almost all colds clear up in less than two weeks without complications. Colds, sometimes called rhinovirus or coronavirus in…
Common variable immunodeficiency is an immunodeficiency disorder characterized by a low level of anti-bodies. Patients with this disease are subject to recurring infections. Immunodeficiency means that the immune system is deficient in one or more of its components and is unable to respond effectively. Common variable immunodeficiency is the most common of the immunodeficiency disorders. Patients …
Complement deficiencies are a group of disorders in which there is a reduced level of specific proteins, complement, involved in proper immune functioning. Complement plays several functions in immunity. It can poke holes in bacteria, kill bacteria that are first targeted by antibodies, or, working with antibodies, point out which bacteria need to be engulfed by white blood cells. Without sufficie…
Computed tomography (CT) scans are completed with the use of a 360-degree x-ray beam and computer production of images. These scans allow for cross-sectional views of body organs and tissues. CT scans are used to image a wide variety of body structures and internal organs. Since the 1990s, CT equipment has become more affordable and available. In some diagnoses, CT scans have become the first imag…
Concussion is a trauma-induced change in mental status, with confusion and amnesia, and with or without a brief loss of consciousness. A concussion occurs when the head hits or is hit by an object, or when the brain is jarred against the skull, with sufficient force to cause temporary loss of function in the higher centers of the brain. The injured person may remain conscious or lose consciousness…
Male condoms are thin sheaths of latex (rubber), polyurethane (plastic), or animal tissue that are rolled onto an erect penis immediately prior to intercourse. They are commonly called "safes" or "rubbers." Female condoms are made of polyurethane and are inserted into the vaginal A condom is most effective when it is placed on the penis correctly without trapping ai…
Conduct disorder (CD) is a behavioral and emotional disorder of childhood and adolescence. Children with conduct disorder act inappropriately, infringe on the rights of others, and violate the behavioral expectations of others. CD is present in approximately 9% of boys and 2–9% of girls under the age of 18. Children with conduct disorder act out aggressively and express anger inappropriatel…
Congenital adrenal hyperplasia is (CAH) a genetic disorder characterized by a deficiency in the hormones cortisol and aldosterone and an over-production of the hormone androgen, which is present at birth and affects sexual development. CAH is a form of adrenal insufficiency in which the enzyme that produces two important adrenal steroid hormones, cortisol and aldosterone, is deficient. Because cor…
Congenital amputation is the absence of a fetal limb or fetal part at birth. This condition may be the result of the constriction of fibrous bands within the membrane that surrounds the developing fetus (amniotic band syndrome) or the exposure to substances known to cause birth defects (teratogenic agents). Other factors, including genetics, may also play a role. An estimated one in 2,000 babies a…
The two most common congenital bladder abnormalities are exstrophy and congenital diverticula. An exstrophic bladder is one that is open to the outside and turned inside-out, so that its inside is visible at birth, protruding from the lower abdomen. A diverticulum is an extension of a hollow organ, usually shaped like a pouch with a narrow opening. During fetal development, folds enclose tissues a…
Congenital brain defects are a group of disorders of brain development. Brain development begins shortly after conception and continues throughout the growth of a fetus. A complex genetic program coordinates the formation, growth, and migration of billions of neurons, or nerve cells, and their development into discrete, interacting brain regions. Interruption of this program, especially early in d…
A condition of abnormal development of the hip, resulting in hip joint instability and potential dislocation of the thigh bone from the socket in the pelvis. This condition has been more recently termed developmental hip dysplasia, as it often develops over the first few weeks, months, or years of life. Congenital hip dysplasia is a disorder in children that is either present at birth or shortly t…
Congenital lobar emphysema is a chronic disease that causes respiratory distress in infants. Congenital lobar emphysema, also called infantile lobar emphysema, is a respiratory disease that occurs in infants when air enters the lungs but cannot leave easily. The lungs become over-inflated, causing respiratory function to decrease and air to leak out into the space around the lungs. Half of the cas…
The ureter drains urine from the kidney into the bladder. It is not simply a tube but an active organ that propels urine forward by muscular action. It has a valve at its bottom end that prevents urine from flowing backward into the kidney. Normally, there is one ureter on each side of the body for each kidney. However, among the many abnormalities of ureteral development, duplication is quite com…
Cardiomyopathy is an ongoing disease process that damages the muscle wall of the lower chambers of the heart. Congestive cardiomyopathy is the most common form of cardiomyopathy. In congestive cardiomyopathy, also called dilated cardiomyopathy, the walls of the heart chambers stretch (dilate) to hold a greater volume of blood than normal. Congestive cardiomyopathy is the final stage of many heart …
Congenital heart disease, also called congenital heart defect, includes a variety of malformations of the heart or its major blood vessels that are present at birth. Congenital heart disease occurs when the heart or blood vessels near the heart do not develop properly before birth. Some infants are born with mild types of congenital heart disease, but most need surgery in order to survive. Patient…
Conjuctivitis is an inflammation or redness of the lining of the white part of the eye and the underside of the eyelid (conjunctiva) that can be caused by infection, allergic reaction, or physical agents like infrared or ultra-violet light. Conjunctivitis is the inflammation of the conjunctiva, a thin, delicate membrane that covers the eyeball and lines the eyelid. Conjunctivitis is an extremely c…
Constipation is an acute or chronic condition in which bowel movements occur less often than usual or consist of hard, dry stools that are painful or difficult to pass. Bowel habits vary, but an adult who has not had a bowel movement in three days or a child who has not had a bowel movement in four days is considered constipated. Constipation is one of the most common medical complaints in the Uni…
Contact dermatitis is the name for any skin inflammation that occurs when the skin's surface comes in contact with a substance originating outside the body. There are two kinds of contact dermatitis, irritant and allergic. Thousands of natural and man-made substances can cause contact dermatitis, which is the most common skin condition requiring medical attention and the foremost source of …
Contraception (birth control) prevents pregnancy by interfering with the normal process of ovulation, fertilization, Various types of contraception. (Photo Researchers, Inc. Reproduced by permission.) and implantation. There are different kinds of birth control that act at different points in the process. Every month, a woman's body begins the process that can potentially lead to pre…
Contractures are the chronic loss of joint motion due to structural changes in non-bony tissue. These non-bony tissues include muscles, ligaments, and tendons. Contractures can occur at any joint of the body. This joint dysfunction may be a result of immobilization from injury or disease; nerve injury, such as spinal cord damage and stroke; or muscle, tendon, or ligament disease. There are a numbe…
Cooling treatments lower body temperature in order to relieve pain, swelling, constriction of blood vessels, and to decrease the liklihood of cellular damage by slowing the metabolism. Sponge baths, cold compresses, and cold packs are all wet cooling treatments. Dry treatments, such as ice bags and chemical cold packs, are also used to lower body temperature. The most common reason for cooling a b…
Coombs' tests are blood tests that identify the causes of anemia. Anemia, which literally means no blood, refers to blood with abnormally low oxygen-carrying capacity. The hemoglobin in red blood cells carries oxygen. One of the many causes of anemia is destruction of red blood cells, a process called hemolysis (hemo means blood and lysis means disintegration). A simple blood count detects …
Cor pulmonale is an increase in bulk of the right ventricle of the heart, generally caused by chronic diseases or malfunction of the lungs. This condition can lead to heart failure. Cor pulmonale, or pulmonary heart disease, occurs in 25% of patients with chronic obstructive pulmonary disease (COPD). In fact, about 85% of patients diagnosed with cor pulmonale have COPD. Chronic bronchitis and emph…
A corneal abrasion is a worn or scraped-off area of the outer, clear layer of the eye (cornea). The cornea is the clear, dome-shaped outer area of the eye. It lies in front of the colored part of the eye (iris) and the black hole in the iris (pupil). The outermost layer of the eyeball consists of the cornea and the white part of the eye (sclera). A corneal abrasion is basically a superficial cut o…
In corneal transplant, also known as keratoplasty, a patient's damaged cornea is replaced by the cornea from the eye of a human cadaver. This is the single most common type of human transplant surgery and has the highest success rate. Eye banks acquire and store eyes from donor individuals largely to supply the need for transplant corneas. Corneal transplant is used when vision is lost in a…
The cornea, the clear front part of the eye through which light passes, is subject to many infections and to A close-up view of an ulcer on cornea. (Custom Medical Stock Photo. Reproduced by permission.) injury from exposure and from foreign objects. Infection and injury cause inflammation of the cornea—a condition called keratitis. Tissue loss because of inflammation produces an ulc…
A corn is a small, painful, raised bump on the outer skin layer. A callus is a rough, thickened patch of skin. Corns and calluses are one of the three major foot problems in the United States. The other two are foot infections and toenail problems. Corns and calluses affect about 5% of the population. Corns usually appear on non-weight-bearing areas like the outside of the little toe or the tops o…
Coronary artery bypass graft surgery is a surgical procedure in which one or more blocked coronary arteries are bypassed by a blood vessel graft to restore normal blood flow to the heart. These grafts usually come from the patient's own arteries and veins located in the leg, arm, or chest. Coronary artery bypass graft surgery (also called coronary artery bypass surgery, CABG, and bypass ope…
Coronary artery disease is a narrowing or blockage of the arteries and vessels that provide oxygen and nutrients to the heart. It is caused by atherosclerosis, an accumulation of fatty materials on the inner linings of arteries. The resulting blockage restricts blood flow to the heart. When the blood flow is completely cut off, the result is a heart attack. Coronary artery disease, also called cor…
A coronary stent is an artificial support device used in the coronary artery to keep the vessel open. The coronary stent is a relatively new tool used to keep coronary arteries expanded, usually following a balloon angioplasty. Balloon angioplasty is used in patients with coronary artery disease. In this disease, the blood vessels on the heart become narrow. When this happens, the oxygen supply is…
Corticosteriods are a group of natural and synthetic analogues of the hormones secreted by the hypothalamic-anterior pituitary-adrenocortical (HPA) axis, more commonly referred to as the pituitary gland. These include glucocorticoids, which are anti-inflammatory agents with a large number of other functions; mineralocorticoids, which control salt and water balance primarily through action on the k…
This test is a measure of serum cortisol (also known as hydrocortisone), or urine cortisol (also known as urinary free cortisol), an important hormone produced by a pair of endocrine glands called the adrenal glands. This test is performed on patients who may have malfunctioning adrenal glands. Blood and urine cortisol, together with the determination of adrenocorticotropic hormone (ACTH), are the…
Cosmetic dentistry includes a variety of dental treatments aimed at improving the appearance of the teeth. The purpose of cosmetic dentistry is to improve the appearance of the teeth using bleaching, bonding, veneers, reshaping, orthodontics, or implants. Bleaching is done to lighten teeth that are stained or discolored. It entails the use of a bleaching solution applied by a dentist or a gel in a…
Costochondritis is an inflammation and associated tenderness of the cartilage (i.e., the costochondral joints) that attaches the front of the ribs to the breastbone. Costochondritis causes pain in the lower rib area or upper breastbone. Some patients fear they are having a heart attack. The most severe pain is usually between the breast and the upper abdomen. The pain may be greater when in sittin…
A cough is a forceful release of air from the lungs that can be heard. Coughing protects the respiratory system by clearing it of irritants and secretions. While people can generally cough voluntarily, a cough is usually a reflex triggered when an irritant stimulates one or more of the cough receptors found at different points in the respiratory system. These receptors then send a message to the c…
Cough suppressants are medicines that prevent or stop coughing. Cough suppressants act on the center in the brain that controls the cough reflex. They are meant to be used only to relieve dry, hacking coughs associated with colds and flu. They should not be used to treat coughs that bring up mucus or the chronic coughs associated with smoking, asthma, emphysema or other lung problems. Many cough m…
