Tremor is an unintentional (involuntary), rhythmical alternating movement that may affect the muscles of any part of the body. Tremor is caused by the rapid alternating contraction and relaxation of muscles and is a common symptom of diseases of the nervous system (neuro-logic disease). Occasional tremor is felt by almost everyone, usually as a result of fear or excitement. However, uncontrollable…
Trench fever is a bacterial infection that causes repeated cycles of high fever. The term trench fever refers to the crowded conditions in which troops fought in during World War I and World War II. Because the causative bacteria are passed among humans through contact with body lice, over-crowding, and conditions which interfere with good hygiene (including regular washing of clothing) soldiers w…
Trichinosis is a disease caused by a roundworm (nematode) called Trichinella spiralis. An individual worm of this species is called a trichina, from the Greek word meaning "hairlike." Trichinae can be readily avoided by proper handling and cooking of certain meats, particularly pork products. A Trichinella spiralis cyst in striated muscle tissue. T. spiralis cysts can survive up …
Trichomoniasis refers to an infection of the genital and urinary tract. Trichomoniasis is caused by a protozoan (the smallest, single-celled members of the animal kingdom). Trichomonas vaginalis is passed almost 100% of the time through sexual contact. Trichomoniasis is primarily an infection of women's vaginal and urinary tracts. A woman is most susceptible to infection just after having c…
Tricuspid valve insufficiency occurs when a tricuspid valve does not close tightly enough to prevent leakage. This condition is also called tricuspid valve regurgitation and tricuspid incompetence. The tricuspid valve is located between the right atrium and the right ventricle of the heart. When the right ventricle contracts, it is supposed to pump blood forward into the lungs. If the tricuspid va…
Tricuspid valve stenosis is a narrowing or stiffening of the opening in the valve. This stenosis causes increased resistance to blood flow through the valve. The tricuspid valve is located between the right atrium and the right ventricle of the heart. It is the largest of the four valves in the heart. When the tricuspid valve is narrowed or stiffened, it decreases the amount of blood that can flow…
Trigeminal neuralgia is a disorder of the trigeminal nerve (the fifth cranial nerve) that causes episodes of sharp, stabbing pain in the cheek, lips, gums, or chin on one side of the face. The trigeminal nerve, which is divided into three branches, is responsible for chewing, for producing saliva and tears, and for sending facial sensations to the brain. When this nerve breaks down for some reason…
Trigger finger is the popular name of stenosing tenosynovitis, a painful condition in which a finger or thumb locks when it is bent (flexed) or straightened (extended). Tendons are tough, fibrous cords that connect muscles to bones. Tendons must slide easily through their protective coverings (tendon sheaths). The finger and thumb bones have tendons that are responsible for bending and straighteni…
Triglycerides test is a blood test to determine the amount of triglycerides, a form of fat, in the blood. The triglycerides test is one of the screening tests for excess lipids (fats) in the blood. It is usually part of an evaluation of risk factors for heart disease. Triglycerides are a form of fat that comes from foods. They can also be made and stored in the body and are used as an energy sourc…
Tropical spastic paraparesis (TSP) is an incurable viral infection of the spinal cord that causes weakness in the legs. It is caused by the human T-cell lymphotropic virus-1 (HTLV-1) retrovirus. As the name implies, tropical spastic paraparesis usually occurs in tropical locales. Although isolated cases have been diagnosed in the southeastern United States and other places in the United States, TS…
Troponins are specific proteins found in heart muscle. Troponin testing is done to diagnose heart attacks (myocardial infarctions). When heart muscle is damaged, as in a myocardial infarction (MI), troponins leak out of cells and into the bloodstream. Increased troponin levels indicate myocardial infarction or injury in a person with chest pain or pressure. Some MIs are silent, manifesting few if …
Tubal ligation is a permanent voluntary form of birth control (contraception) in which a woman's Fallopian tubes are surgically cut or blocked off to prevent pregnancy. Tubal ligation is performed in women who definitely want to prevent future pregnancies. It is frequently chosen by women who do not want more children, but who are still sexually active and potentially fertile, and want to b…
Tube compression of the esophagus and stomach is an emergency procedure used to stop bleeding from the upper digestive tract. Vomiting blood is both frightening and life-threatening. Among its causes are: The most profuse bleeding comes from veins in the lower esophagus, just above the stomach, that have dilated to enormous dimensions as the result of liver disease. When the liver shrinks due to c…
Nutrients, either a special liquid formula or pureed food, are delivered to a patient through a tube directly into the gastrointestinal tract, usually into the stomach or small intestine. Tube feeding provides nutrition to patients who are unable or unwilling to eat food. Conditions where tube feeding is considered include protein-energy malnutrition, liver or kidney failure, coma, or in patients …
Tuberculosis (TB) is an airborne infectious disease caused by the bacteria Mycobacterium tuberculosis. Besides culturing in the laboratory, the two most common types of tests to screen for exposure to this disease are the Mantoux PPD tuberculin skin test, which is generally considered the most reliable, and the older TB tine test, which is now rarely used. These tests are designed to help identify…
Tuberculosis (TB) is a potentially fatal contagious disease that can affect almost any part of the body but is mainly an infection of the lungs. It is caused by a bacterial microorganism, the tubercle bacillus or Mycobacterium tuberculosis. Although TB can be treated, cured, and can be prevented if persons at risk take certain drugs, scientists have never come close to wiping it out. Few diseases …
Tularemia is an illness caused by a bacterium. It results in fever, rash, and greatly enlarged lymph nodes. Tularemia infects a variety of wild animals, including rabbits, deer, squirrels, muskrat, and beaver. Humans can acquire the bacterium directly from contact with the blood or body fluids of these animals, from the bite of a tick or fly which has previously fed on the blood of an infected ani…
Tumor markers are substances, such as proteins, biochemicals, or enzymes, produced by tumor cells or by the body in response to tumor cells. As tumor cells multiply, cancer spreads, and tissue is damaged, these substances increase and leak into the bloodstream. Tumor marker levels in blood help physicians evaluate people for certain types of cancer. Tumor marker levels provide evidence about the l…
Tumor removal is a surgical procedure to remove an abnormal growth. A tumor can be either benign, like a wart, or malignant, in which case it is a cancer. Benign tumors are well A tumor inside the brain is being removed. (Photograph by Jennifer Watson-Holton, Custom Medical Stock Photo. Reproduced by permission.) circumscribed and are generally easy to remove completely. In contrast, cancer…
Turner syndrome is a chromosomal disorder affecting females wherein one of the two X-chromosomes is defective or completely absent. Chromosomes are structures in the nucleus of every cell in the human body. Chromosomes contain the genetic information necessary to direct the growth and normal functioning of all cells and systems of the body. A normal individual has a total of 46 chromosomes in each…
Typhoid fever is a severe infection caused by a bacterium, Salmonella typhi. S. typhi is in the same family of bacteria as the type spread by chicken and eggs, commonly known as "salmonella poisoning," or food poisoning. S. typhi bacteria do not have vomiting and diarrhea as the most prominent symptoms of their presence in humans. Instead, persistently high fever is the hallmark of S…
Several different illnesses called "typhus" exist, all of them caused by one of the bacteria in the family Rickettsiae. Each illness occurs when the bacteria is passed to a human through contact with an infected insect. The four main types of typhus are: These diseases are all somewhat similar, although they vary in terms of severity. The specific type of Rickettsia that causes the d…
Tzanck preparation is a rapid test done to diagnose infections caused by herpesviruses. Cells are examined under a microscope for signs of infection. Herpesviruses are responsible for several superficial infections. Varicella zoster virus causes chickenpox and shingles, herpes simplex type 1 causes the common cold sore or fever blister, and herpes simplex type 2 causes the sexually transmitted dis…
Ulcer surgery is a procedure used to cure peptic ulcer disease when medications have failed. Ulcer surgery is used to relieve a present peptic ulcer disease and to prevent recurrence of it. Surgery is usually required if the ulcer is in one of the following states: The need for ulcer surgery has diminished greatly over the past 20–30 years due to the discovery of two new classes of drugs an…
Ulcerative colitis is a form of inflammatory bowel disease (IBD). It causes swelling, ulcerations, and loss of function of the large intestine. The primary problem in IBD is inflammation, as the name suggests. Inflammation is a process that often occurs in order to fight off foreign invaders in the body, including viruses, bacteria, and fungi. In response to such organisms, the body's immun…
In general, an ulcer is any eroded area of skin or a mucous membrane, marked by tissue disintegration. In common usage, however, ulcer is usually used to refer to disorders in the upper digestive tract. The terms ulcer, gastric ulcer, and peptic ulcer are often used loosely and interchangeably. Peptic ulcers can develop in the lower part of the esophagus, the stomach, the first part of the small i…
Ultraviolet light treatment uses a particular band of the nonvisible light spectrum to treat psoriasis and a variety of other skin diseases. It can be used alone or in combination with other medications applied directly to the skin or taken internally. Ultraviolet (UV) light treatment is used primarily in cases of severe psoriasis that have not responded to other medications or in cases affecting …
Also known as cryptorchidism, undescended testes is a congenital condition characterized by testicles that do not extend to the scrotum. In the fetus, the testes are in the abdomen. As development progresses they migrate downward through the groin and into the scrotum. This event takes place late in fetal development, during the eighth month of gestation. Thirty percent of premature boys have test…
An upper GI examination is a fluoroscopic examination (a type of x-ray imaging) of the upper gastrointestinal tract, including the esophagus, stomach, and upper small intestine (duodenum). An upper GI series is frequently requested when a patient experiences unexplained symptoms of abdominal pain, difficulty in swallowing (dysphagia), regurgitation, diarrhea, or weight loss. It is used to help dia…
Ureteral stents are thin catheters threaded into segments of the ureter that carry urine, produced by the kidney, either down into the bladder internally, or to an external collection system. Insertion is most often done through the skin (percutaneously); however, in the presence of kidney or ureteral stones, stenting is ideally done during cystoscopy. Ureteral stenting may be placed on a long-ter…
Urethritis is an inflammation of the urethra that is usually caused by an infection. The urethra is the canal that moves urine from the bladder to the outside of the body. When this canal becomes infected, inflammation occurs due to the accumulation of white blood cells in the area. When this occurs, it is called urethritis. Besides the urethra, the urinary tract consists of the bladder, ureters, …
Uric acid tests are tests that are done to measure the levels of uric acid in blood serum or in urine. The uric acid tests are used to evaluate the blood levels of uric acid for gout and to assess uric acid levels in the urine for kidney stone formation. The urine test is used most often to monitor patients already diagnosed with kidney stones, but it can also be used to detect disorders that affe…
Urinalysis is a diagnostic physical, chemical, and microscopic examination of a urine sample (specimen). Specimens can be obtained by normal emptying of the bladder (voiding) or by a hospital procedure called catheterization. Urinalyses are performed for several reasons: Urinalysis should not be performed while a woman is menstruating or having a vaginal discharge. A woman who must have a urinalys…
Urinary anti-infectives are medicines used to treat or prevent infections of the urinary tract—the passage through which urine flows from the kidneys out of the body. Normally, no bacteria or other disease-causing organisms live in the bladder. Likewise, the urethra—the tubelike structure that carries urine from the bladder out of the body—usually has either no bacteria or not…
Urinary catheterization is the insertion of a catheter into a patient's bladder. The catheter is used as a conduit to drain urine from the bladder into an attached bag or container. Urinary catheterization is employed in hospital and nursing home settings to maintain urine output in patients who are undergoing surgery, or who are confined to the bed and physically unable to use a bedpan. Cr…
A urinary diversion involves removal of the urinary bladder and adjacent tissues and organs, and re-routing of the urinary stream. This may involve creation of an artificial opening in the abdomen called an ostomy. A urinary diversion is created as a means to treat cancer of the bladder, when conservative measures have been unsuccessful, or when there is recurrence of the disease invading the musc…
Urinary incontinence is unintentional loss of urine that is sufficient enough in frequency and amount to cause physical and/or emotional distress in the person experiencing it. Approximately 13 million Americans suffer from urinary incontinence. Women are affected by the disorder more frequently than are men; one in 10 women under age 65 suffer from urinary incontinence. Older Americans, too, are …
A urine culture is a diagnostic laboratory test performed to detect the presence of bacteria in the urine (bacteriuria). Culture of the urine is a method of diagnosis for urinary tract infection that determines the number of microorganisms present in a given quantity of urine. If delivery of the urine specimen to the laboratory within one hour of collection is not possible, it should be refrigerat…
A urine flow test evaluates the speed of urination, or amount voided per second, and the total time of urination. A urine flow test is utilized to determine bladder function abnormalities, including a narrowed or obstructed urethra (the outflow passage from the bladder) and a weakened bladder muscle (detrusor). During a urine flow test, the patient urinates into a uroflowmeter, a funnel-shaped dev…
Uterine fibroids (also called leiomyomas or myomas) are benign growths of the muscle inside the uterus. They are not cancerous, nor are they related to cancer. Fibroids can cause a wide variety of symptoms, including heavy menstrual bleeding and pressure on the pelvis. Uterine fibroids are extremely common. About 25% of women in their reproductive years have noticeable fibroids. There are probably…
Uveitis is an inflammation of the uveal tract, which lines the inside of the eye behind the cornea. Much of the uvea lies between the retina and tough, outer sclera. The uveal tract has three parts: the iris, the ciliary body, and the choroid. Uveitis is categorized according to the part of the uveal tract that is affected. Anterior uveitis is an inflammation of the front part of the uveal tract; …
Vaccination is the use of vaccines to prevent specific diseases. Many diseases that once caused widespread illness, disability, and death now can be prevented through the use of vaccines. Vaccines are medicines that contain weakened or dead bacteria or viruses. When a person takes a vaccine, his or her immune system responds by producing antibodies—substances that weaken or destroy disease-…
Pain in the vaginal canal is usually associated with an underlying medical and/or psychological condition. Vaginal pain is experienced usually during vaginal manipulation or sexual intercourse. Approximately 50–85% of the causes are due to organic (medical) conditions. However, it is typical for the medical condition to be compounded by psychological issues such as depression and problems a…
Vagotomy is the surgical cutting of the vagus nerve to reduce acid secretion in the stomach. The vagus nerve splits into branches that go to different parts of the stomach. Stimulation from these branches causes the stomach to produce acid. Too much stomach acid leads to ulcers that may eventually bleed and create an emergency situation. Vagotomy is performed when acid production in the stomach ca…
The Valsalva maneuver is performed by attempting to forcibly exhale while keeping the mouth and nose closed. It is used as a diagnostic tool to evaluate the condition of the heart and is sometimes done as a treatment to correct abnormal heart rhythms or relieve chest pain. The Valsalva maneuver is used with patients who have suspected heart abnormalities, often in conjunction with echocardiography…
Valvular heart disease refers to several disorders and diseases of the heart valves, which are the tissue flaps that regulate the flow of blood through the four chambers of the heart. The human heart consists of four chambers—two upper chambers (the atria) and two lower chambers (the ventricles)—that are responsible for pumping blood. The heart valves are like one-way doors, which op…
Varicose veins are dilated, tortuous, elongated superficial veins that are usually seen in the legs. Varicose veins, also called varicosities, are seen most often in the legs, although they can be found in other parts of the body. Most often, they appear as lumpy, winding vessels just below the surface of the skin. There are three types of veins, superficial veins that are just beneath the surface…
Vasculitis refers to a varied group of disorders which all share a common underlying problem of inflammation of a blood vessel or blood vessels. The inflammation may affect any size blood vessel, anywhere in the body. It may affect either arteries and/or veins. The inflammation may be focal, meaning that it affects a single location within a vessel; or it may be widespread, with areas of inflammat…
A vasectomy is a surgical procedure performed on males in which the vas deferens (tubes that carry sperm from the testicles to the seminal vesicles) are cut, tied, cauterized (burned or seared) or otherwise interrupted. The semen no longer contains sperm after the tubes are cut, so conception cannot occur. The testicles continue to produce sperm, but they die and are absorbed by the body. The purp…
Vasodilators are medicines that act directly on muscles in blood vessel walls to make blood vessels widen (dilate). Vasodilators are used to treat high blood pressure (hypertension). By widening the arteries, these drugs allow blood to flow through more easily, reducing blood pressure. Controlling high blood pressure is important because the condition puts a burden on the heart and the arteries, w…
Vegetarianism is the voluntary abstinence from eating meat. Vegetarians refrain from eating meat for various reasons, including religious, health, and ethical ones. Lacto-ovo vegetarians supplement their diet with dairy (lactose) products and eggs (ovo). Vegans (pronounced vee-guns) do not eat any animal-derived products at all. Vegetarianism is recommended as a dietary therapy for a variety of co…
A coma-like state characterized by open eyes and the appearance of wakefulness is defined as vegetative. The vegetative state is a chronic or long-term condition. This condition differs from a persistent vegetative state (PVS, a state of coma that lacks both awareness and wakefulness) since patients have awakened from coma, but still have not regained awareness. In the vegetative state patients ca…
Velopharyngeal insufficiency is the improper closing of the velopharyngeal sphincter (soft palate muscle) during speech characterized by an acute nasal quality of the voice. At the back of the mouth is a circle of structures that include the tonsils, the tongue, and the palate. During speech, this apparatus must close off the nose for proper articulation of the explosive consonants "p,�…
A vena cava filter is a device inserted into a major vein to prevent a blood clot from entering the lungs. The purpose of a vena cava filter is to prevent a blood clot from potentially traveling to the lungs. A thrombus clot traveling to the lungs is called a pulmonary embolism (PE). A thrombus in the deep venous system (the part of the circulation that brings blood back to the heart) represents a…
Venography is an x-ray test that provides an image of the leg veins after a contrast dye is injected into a vein in the patient's foot. Venography is primarily performed to diagnose deep vein thrombosis (a condition that can lead to pulmonary embolism). It is the standard procedure used to detect this type of disorder. Venography can also be used to distinguish blood clots from obstructions…
Venous access introduces a needle into a vein, usually for the purpose of withdrawing blood or administering medication. Venous access is necessary for fluid administration, medication administration, and obtaining blood for chemical analysis. Sites for access include veins located in the peripheral arms or legs, scalp, neck, and bone. Venous access in children may pose special problems since find…
Venous insufficiency is described as abnormal blood flow through veins that can cause local damage, damage to affected legs, or death. Syndromes related to venous insufficiency are caused by valve incompetence. Venous insufficiency is a chronic (long term) condition. The number of new and existing cases is dependent on age and gender. Some patients may have a positive family history. Usually older…
Ventricular aneurysm is a complication of a heart attack (myocardial infarction). It is a ballooning of a section of a blood vessel in the heart that first appears several days or weeks after an acute myocardial infarction. A myocardial infarction occurs when a section of the heart wall is deprived of blood and dies (undergoes necrosis, or tissue death, and scarring). The heart wall is mainly musc…
A ventricular assist device (VAD) is a mechanical pump used for temporary blood circulation support. It decreases the workload of the heart while maintaining adequate flow and blood pressure. A VAD is a temporary life-sustaining device. VADs can replace the left ventricle (LVAD), the right ventricle (RVAD), or both ventricles (BIVAD). They are used when the heart muscle is damaged and needs to res…
A ventricular ectopic beat (VEB) is an extra heartbeat originating in the lower chamber of the heart. This beat, also called a premature ventricular contraction (PVC), occurs before the beat triggered by the heart's normal function. Ventricular ectopic beats are common and do not indicate a problem in people without heart disease. However, if a person has aortic stenosis, heart failure, or …
