Definition Sexual dysfunction is broadly defined as the inability to fully enjoy sexual intercourse. Specifically,sexual dysfunctions are disorders that interfere with a full sexual response cycle. These disorders make it difficult for a person to enjoy or to have sexual intercourse. While sexual dysfunction rarely threatens physical health, it can take...

Definition The rubella test is a routine blood test performed as part of prenatal care of pregnant women. It is sometimes also used to screen women of childbearing age before the first pregnancy. Purpose The test is given to evaluate whether a woman is immune to rubella (German measles ) as a result of childhood exposure or immunization, or whether...

Definition Rubella, also called German measles or three-day measles, is a highly contagious viral disease that in most children and adults causes mild symptoms of low fever , swollen glands, joint pain , and a fine red rash. Although rubella causes only mild symptoms in child and adult sufferers, the infection can have severe complications for the fetus of a woman who...

Definition Roundworm infections are diseases of the digestive tract and other organ systems caused by nematodes. Nematodes are parasitic worms with long, cylindrical bodies. Description Roundworm infections are widespread throughout the world, with some regional differences. Ascariasis and trichuriasis are more common in warm, moist climates where people use human or animal feces for fertilizer....

Definition Rotavirus is the major cause of diarrhea and vomiting in young children worldwide. The infection is highly contagious and may lead to severe dehydration (loss of body fluids) and even death. Description Gastroenteritis (inflammation of the stomach and the intestine) is the second most common illness in the United States, after the common cold . More...

Definition Ross River Virus (RRV) is Australia's most common and widespread mosquito-borne pathogen. Also known as RRV disease, it can cause debilitating polyarthritis, rash, fever, and constitutional symptoms. Description Originally known as epidemic polyarthritis, RRV is a member of the Togaviridae family of arboviruses. RRV is transmitted in an animal host-vector-human...

Definition Roseola is a common disease of babies or young children, in which several days of very high fever are followed by a characteristic rash. Demographics Roseola is an extraordinarily common infection, caused by a virus. About 90 percent of all children have been exposed to the virus, with about 33 percent actually demonstrating the syndrome of fever followed by rash. The most common age...

Definition Rosacea is an acne-like chronic facial skin disorder affecting about 14 million citizens of the United States, especially persons with fair skin and who blush easily. Rosacea usually first appears intermittently when people are in the 30s, 40s, or 50s as a redness on cheeks, nose, chin, or forehead. This early stage is often dismissed as a complexion problem or as a sunburn. If the...

Definition Root canal treatment, also known as endodontic treatment, is a dental procedure in which the diseased or damaged pulp (core) of a tooth is removed and the inside areas (the pulp chamber androot canals) are filled and sealed. Purpose Inflamed or infected pulp (pulpitis) most often causes a toothache. To relieve the pain and prevent further complications, the...

Definition Rolfing, also called Rolf therapy or structural integration, is a holistic system of bodywork that uses deep manipulation of the body's soft tissue to realign and balance the body's myofascial structure.Rolfing improves posture, relieves chronic pain , and reduces stress . Origins Ida Pauline Rolf (1896–1979) was a biochemist from New York who developed structural...

Definition Rocky Mountain spotted fever (RMSF) is a tick-borne illness caused by a bacteria, resulting in a high fever and a characteristic rash. Description The bacteria causing RMSF is passed to humans through the bite of an infected tick. The illness begins within about two weeks of such a bite. RMSF is the most...

Definition Ringworm is a common fungal infection of the skin. The name is a misnomer since the disease is not caused by a worm. Description More common in males than in females, ringworm is characterized by patches of rough,reddened skin. Raised eruptions usually form the circular pattern that gives the condition...

Definition Rickettsialpox is a relatively mild disease caused by a member of the bacterial family called Rickettsia. Rickettsialpox causes rash, fever, chills, heavy sweating, headache, eye pain(especially when exposed to light), weakness, and achy muscles. Description Like other members of the family of Rickettsia, the bacteria causing rickettsialpox live in...

Definition Rickets is a childhood condition caused by serious vitamin D deficiency. This lacking in vitamin D results in weak, soft bones, along with slowed growth and skeletal development. Rickets is, by definition, a disorder which begins in childhood. If this problem occurs only later in life it is known as osteomalacia. Description Rickets occurs when the body has a severe lack...

Definition Riboflavin deficiency occurs when the chronic failure to eat sufficient amounts of foods that contain riboflavin produces lesions of the skin, lesions of smooth surfaces in the digestive tract, or nervous disorders. Description Riboflavin, also called vitamin B2, is a water-soluble vitamin. The recommended dietary allowance (RDA) for riboflavin is 1.7 mg/day for an adult...

Definition The term rhinoplasty means "nose molding" or "nose forming." It refers to a procedure in plastic surgery in which the structure of the nose is changed. The change can be made by adding or removing bone or cartilage, grafting tissue from another part of the body, or implanting synthetic material to alter the shape of the nose. Rhinoplasty is the most frequently...

Definition Rhinitis is inflammation of the mucous lining of the nose. Description Rhinitis is a nonspecific term that covers infections, allergies , and other disorders whose common feature is the location of their symptoms. In rhinitis, the mucous membranes become infected or irritated, producing a discharge, congestion, and swelling of the tissues. The most widespread form of infectious rhinitis is...

Definition Rheumatoid arthritis is a chronic inflammatory autoimmune joint disease that causes pain, stiffness, swelling, and decreased movement in joints. Unchecked, it can lead to the eventual joint destruction. Description Rheumatoid arthritis is a painful disease that causes joints to swell and become stiff and restricts their range of motion. People of any age, including children, can...

Rheumatic fever is a rare complication that occurs after an infection with Streptococcus pyogenes bacteria . The most common type of S. pyogenes infection is "strep throat," in which the tissues that line the pharynx become infected with the bacteria. Rheumatic fever does not occur if the initial strep infection is treated with antibiotics ....

Definition Retrograde urethrography involves the use of x-ray pictures to provide visualization of structural problems or injuries to the urethra. Purpose Retrograde urethrography is used, in combination with a doctor's observation and other tests, to establish a diagnosis for individuals, almost exclusively men, who may have structural problems of the urethra. Precautions The doctor...

Definition A retrograde ureteropyelogram provides x-ray visualization of the bladder, ureters, and the kidney (renal) pelvis by injection of sterile dye into the renal collecting system. Purpose A retrograde ureteropyelogram is performed to determine the exact location of a ureteral obstruction when it cannot be visualized on an intravenous pyelogram (a dye is injected and an x ray taken...

Definition A retrograde cystogram is a radiographic study of the bladder, made after a direct injection of a radiopaque contrast material by means of a urethral catheter. Purpose A retrograde cystogram is performed to evaluate the structure of the bladder and identify such bladder disorders as cystitis, polyps, stones, and tumors. It may also be used to diagnose recurrent urinary tract infections...

Definition Retinopathy is a noninflammatory disease of the retina. There are many causes and types of retinopathy. Description The retina is the thin membrane that lines the back of the eye and contains light-sensitive cells (photoreceptors). Light enters the eye and is focused onto the retina. The photoreceptors send a message to the brain via the optic nerve. The brain then "interprets" the electrical...

Definition Retinoblastoma is a cancer affecting one or both eyes. It occurs mainly in children under the age of four. Its name is derived from the area of the eye that is affected, the retina. The retina is the part of the eye that captures the images of the outside world and transfers these images to the brain. If the eye is thought of as a camera, the retina can be thought of as the film in...

Definition Retinitis pigmentosa (RP) refers to a group of inherited disorders that slowly leads to blindness due to abnormalities of the photoreceptors (primarily the rods) in the retina. Description The retina lines the interior surface of the back of the eye. The retina is made up ofseveral layers. One layer contains two...

Definition Retinal vein occlusion refers to the closure of the central retinal vein that drains the retina or to that of one of its branches. Description Retinal vein occlusion (RVO) occurs when the central retinal vein, the blood vessel that drains the retina, or one of its branches becomes blocked. RVO may be categorized by the anatomy of the occluded vein and...

Definition Retinal hemorrhage is the abnormal bleeding of the blood vessels in the retina, the membrane in the back of the eye. Description The retina is the part of the eye that converts light into nerve signals that are processed by the brain into visual images. The retina is the inside surface of the back of the eye, consisting of millions of densely arranged, light-sensitive cells called rods and...

Definition Retinal detachment is the separation of the retina of the eye from its underlying layer of tissue. This separation results in loss of vision. Retinal detachment is a medical emergency. Description The retina is a thin layer of light-sensitive cells about the size of a postage stamp located at the back of the eyeball. Underneath the retina lies a layer of cells called the retinal pigment...

Definition Retinal artery occlusion refers to the closure of the central retinal artery and usually results in complete loss of vision in one eye. Occlusion of its branches causes loss of vision in only a portion of the field of vision. Description Retinal artery occlusion (RAO) occurs when the central retinal artery, the main source of blood supply...

Definition A reticulocyte count is a blood test performed to assess the body's production of immature red blood cells (reticulocytes). A reticulocyte count is usually performed when patients are evaluated for anemia and response to its treatment. It is sometimes called a retic count. Purpose Diagnosis A reticulocyte count provides information about the rate...

Definition Cardiomyopathy is an ongoing disease process that damages the muscle wall of the lower chambers of the heart. Restrictive cardiomyopathy is a form of cardiomyopathy in which the walls of the heart become rigid. Description Restrictive cardiomyopathy is the least common type of cardiomyopathy in the United States. The stiffened heart walls cannot stretch...

Definition Restless legs syndrome (RLS) is characterized by unpleasant sensations in the limbs,usually the legs, that occur at rest or before sleep and are relieved by activity such as walking. These sensations are felt deep within the legs and are described as creeping, crawling, aching, or fidgety. Description Restless legs syndrome,...

Definition Respiratory syncytial virus (RSV) is a virus that can cause severe lower respiratory infections in children younger than two years of age and milder upper respiratory infections in older children and adults. RSV infection in young children is also called bronchiolitis , because it is marked...

Definition Respiratory failure is nearly any condition that affects breathing function or the lungs themselves and can result in failure of the lungs to function properly. The main tasks of the lungs and chest are to get oxygen from the air that is inhaled into the bloodstream, and, at the same to time, to eliminate carbon dioxide (CO2) from the blood through air that is breathed out. In respiratory failure,...

Definition Respiratory distress syndrome (RDS) of the newborn, also known as infant RDS, is anacute lung disease present at birth, which usually affects premature babies. Layers of tissue called hyaline membranes keep the oxygen that is breathed in from passing into the blood. The lungs are said to be airless. Without treatment, the infant will die within a few days after birth, but if oxygen can be provided,...

Definition Respiratory alkalosis is a condition where the amount of carbon dioxide found in the blood drops to a level below normal range. This condition produces a shift in the body's pH balance and causes the body's system to become more alkaline (basic). This condition is brought on by rapid, deep breathing called hyperventilation. Description Respiratory alkalosis is an alkali...

Definition Respiratory acidosis is a condition in which a build-up of carbon dioxide in the blood produces a shift in the body's pH balance and causes the body's system to become more acidic. This condition is brought about by a problem either involving the lungs and respiratory system or signals from the brain that control breathing. Description Respiratory acidosis is...

  Definition Renovascular hypertension is a secondary form of high blood pressure caused by a narrowing of the renal artery. Description Primary hypertension, or high blood pressure, affects millions of Americans. It accounts for over 90% of all cases of hypertension and develops without apparent causes. It is helpful for the clinician to know if a secondary disease is present and...

Definition Renal vein thrombosis develops when a blood clot forms in the renal vein, which carries blood from the kidneys back to the heart. The disorder is not common. Description Renal vein thrombosis occurs in both infants and adults. Onset of the disorder can be rapid (acute) or gradual. The number of people who suffer from renal vein thrombosis is...

Definition Renal tubular acidosis (RTA) is a condition characterized by too much acid in the body due to a defect in kidney function. Description Chemical balance is critical to the body's functioning. Therefore, the body controls its chemicals very strictly. The acid-base balance must be between a pH of 7.35 and 7.45 or trouble will start. Every other chemical in the body is affected by the...

Definition Renal artery stenosis is a blockage or narrowing of the major arteries that supply blood to the kidneys. Description Renal artery stenosis occurs when the flow of blood from the arteries leading to the kidneys is constricted by tissue or artherosclerotic plaque. This narrowing of the arteries diminishes the blood supply to the kidneys, which can cause them to atrophy...

Definition Renal artery occlusion is a blockage of the major arteries that supply blood to the kidneys caused by thrombosis or embolism. Description Renal artery occlusion occurs when the flow of blood from the arteries leading to the kidneys becomes blocked by a blood clot or cholesterol emboli. The lack of oxygenation can lead to necrosis (tissue death) and ultimately, chronic...

Definition Relapsing polychondritis is a disease characterized by autoimmune-like episodic or progressive inflammation of cartilage and other connective tissue, such as the nose, ears, throat, joints, kidneys, and heart. Description Cartilage is a tough, flexible tissue that turns into bone in many places in the body. Bones all start out as cartilage in the fetus. Consequently, children have more cartilage...

Definition Relapsing fever refers to two similar illnesses, both of which cause high fevers. The fevers resolve, only to recur again within about a week. Description Relapsing fever is caused by spiral-shaped bacteria of the genus Borrelia. This bacterium lives in rodents and in insects, specifically ticks and body lice. The form of relapsing fever acquired from ticks...

Definition Reiter's syndrome (RS), which is also known as arthritis urethritica, venereal arthritis, reactive arthritis, and polyarteritis enterica, is a form of arthritis that affects the eyes, urethra, and skin, as well as the joints. It was first described by Hans Reiter, a German physician, during World War I. Description Reiter's syndrome is marked by a cluster of symptoms in...

Definition Reiki is a form of therapy that uses simple hands-on, no-touch, and visualization techniques, with the goal of improving the flow of life energy in a person. Reiki (pronounced ray-key ) means "universal life energy" in Japanese, and Reiki practitioners are trained to detect and alleviate problems of energy flow on the physical, emotional, and spiritual...

Definition Reflexology is a therapeutic method of relieving pain by stimulating predefined pressure points on the feet and hands. This controlled pressure alleviates the source of the discomfort. In the absence of any particular malady or abnormality, reflexology may be as effective for promoting good health and for preventing illness as it may be for relieving symptoms of stress ,...

Definition Reflex tests are simple physical tests of nervous system function. Purpose A reflex is a simple nerve circuit. A stimulus, such as a light tap with a rubber hammer, causes sensory neurons (nerve cells) to send signals to the spinal cord. Here, the signals are conveyed both to the brain and to nerves that control muscles affected by the stimulus. Without any brain intervention,...

Definition Reflex sympathetic dystrophy is the feeling of pain associated with evidence of minor nerve injury. Description Historically reflex sympathetic dystrophy (RSD) was noticed during the Civil War in patients who suffered pain following gunshot wounds that affected the median nerve (a major nerve in the arm). In 1867 the condition was called...

Definition Red blood cell indices are measurements that describe the size and oxygen-carrying protein (hemoglobin) content of red blood cells. The indices are used to help in the differential diagnosis of anemia. They are also called red cell absolute values or erythrocyte indices. Purpose Anemia includes a variety of conditions with the same outcome:...