Digitalis drugs are medicines made from a type of foxglove plant (Digitalis purpurea) that have a stimulating effect on the heart. Digitalis drugs are used to treat heart problems such as congestive heart failure and irregular heartbeat. These medicines help make the heart stronger and more efficient. This, in turn, improves blood circulation and helps relieve the swelling of the hands and ankles …
Dilatation and curettage (D & C) is a gynecological procedure in which the lining of the uterus (endometrium) is scraped away. D & C is commonly used to obtain tissue for micro-scopic evaluation to rule out cancer. D & C may also be used to diagnose and treat heavy menstrual bleeding, and to diagnose endometrial polyps and uterine fibroids. A D & C can be used as a trea…
Diphtheria is a potentially fatal, contagious disease that usually involves the nose, throat, and air passages, but may also infect the skin. Its most striking feature is the formation of a grayish membrane covering the tonsils and upper part of the throat. Like many other upper respiratory diseases, diphtheria is most likely to break out during the winter months. At one time it was a major childh…
Discoid lupus erythematosus (DLE) is a disease in which coin-shaped (discoid) red bumps appear on the skin. The disease called discoid lupus erythematosus only affects the skin, although similar discoid skin lesions can occur in the serious disease called systemic lupus erythematosus (SLE). Only about 10% of all patients with DLE will go on to develop the multi-organ disease SLE. The tendency to d…
One of the most common types of back surgery is disk removal (diskectomy), the removal of an intervertebral disk, the flexible plate that connects any two adjacent vertebrae in the spine. Intervertebral disks act as shock absorbers, protecting the brain and spinal cord from the impact produced by the body's movements. About 150,000 Americans undergo disk removal each year in the United Stat…
In medicine, the terms dislocation and subluxation refer to the displacement of bones that form a joint. These conditions affecting the joint most often result from trauma that causes adjoining bones to no longer align with each other. A partial or incomplete dislocation is called a subluxation. In a healthy joint, the bones are normally held together with tough, fibrous bands called ligaments. Th…
The dissociative disorders are a group of mental disorders that affect consciousness are defined as causing significant interference with the patient's general functioning, including social relationships and employment. In order to have a clear picture of these disorders, dissociation should first be understood. Dissociation is a mechanism that allows the mind to separate or compartmentaliz…
Diuretics are medicines that help reduce the amount of water in the body. Diuretics are used to treat the buildup of excess fluid in the body that occurs with some medical conditions such as congestive heart failure, liver disease, and kidney disease. Some diuretics are also prescribed to treat high blood pressure. These drugs act on the kidneys to increase urine output. This reduces the amount of…
Diverticulosis refers to a condition in which the inner, lining layer of the large intestine (colon) bulges out (herniates) through the outer, muscular layer. These outpouchings are called diverticula. Diverticulitis refers to the development of inflammation and infection in one or more diverticula. Diverticula tend to occur most frequently in the last segment of the large intestine, the sigmoid c…
As a disorder, dizziness is classified into three categories—vertigo, syncope, and nonsyncope nonvertigo. Each category has a characteristic set of symptoms, all related to the sense of balance. In general, syncope is defined by a brief loss of consciousness (fainting) or by dimmed vision and feeling uncoordinated, confused, and lightheaded. Many people experience a sensation like syncope w…
Doppler ultrasonography is a non-invasive diagnostic procedure that changes sound waves into an image that can be viewed on a monitor. Doppler ultrasonography can detect the direction, velocity, and turbulence of blood flow. It is frequently used to detect problems with heart valves or to measure blood flow through the arteries. Specifically, it is useful in the work up of stroke patients, in asse…
Down syndrome is the most common cause of mental retardation and malformation in a newborn. It occurs because of the presence of an extra chromosome. Chromosomes are the units of genetic information that exist within every cell of the body. Twenty-three distinctive pairs, or 46 total chromosomes, are located within the nucleus (central structure) of each cell. When a baby is conceived by the combi…
Drug metabolism is the process by which the body breaks down and converts medication into active chemical substances. Drugs can interact with other drugs, foods, and beverages. Interactions can lessen or magnify the desired therapeutic effect of a drug, or may cause unwanted or unexpected side effects. There are thousands of possible drug-to-drug and drug-to-food interactions, and many medications…
A drug overdose is the accidental or intentional use of a drug or medicine in an amount that is higher than is normally used. All drugs have the potential to be misused, whether legally prescribed by a doctor, purchased over-thecounter at the local drug store, or bought illegally on the street. Taken in combination with other drugs or with alcohol, even drugs normally considered safe can cause dea…
Drug therapy monitoring, also known as Therapeutic Drug Monitoring (TDM), is a means of monitoring drug levels in the blood. TDM is employed to measure blood drug levels so that the most effective dosage can be determined, with toxicity prevented. TDM is also utilized to identify non-compliant patients (those patients who, for whatever reason, either cannot or will not comply with drug dosages as …
These drugs are used to induce (start) or continue labor. The drug decribed here, oxytocin, makes the uterus (womb) contract. Physicians use it to deliberately start labor. Because there are some risks with using oxytocin, this should be done only when there are good medical reasons. Any woman who is being given oxytocin should make sure she has discussed the benefits and risks with her physician.…
Dry mouth, known medically as xerostomia, is the abnormal reduction of saliva due to medication, disease, or medical therapy. Dry mouth due to the lack of saliva can be a serious medical problem. Decreased salivation can make swallowing difficult, can decrease taste sensation, and can promote tooth decay. Dry mouth, resulting from thickened or reduced salvia flow, can be caused by a number of fact…
Duodenal obstruction is a failure of food to pass out of the stomach either from a complete or partial obstruction. The duodenum is the first part of the intestine, into which the stomach, the gall bladder, and the pancreas empty their contents. The pylorus connects the duodenum with the stomach and contains the valve that regulates stomach emptying. Obstruction usually occurs right at this outlet…
Dysfunctional uterine bleeding is irregular, abnormal uterine bleeding that is not caused by a tumor, infection, or pregnancy. Dysfunctional uterine bleeding (DUB) is a disorder that occurs most frequently in women at the beginning and end of their reproductive lives. About half the cases occur in women over 45 years of age, and about one fifth occur in women under age 20. Dysfunctional uterine bl…
Dyslexia is a learning disability characterized by problems in reading, spelling, writing, speaking, or listening. In many cases, dyslexia appears to be inherited. The word dyslexia is derived from the Greek word, dys (meaning poor or inadequate) and the word lexis (meaning words or language). The National Institutes of Health estimates that about 15% of the United States population is affected by…
Dysmenorrhea is the occurrance of painful cramps during menstruation. More than half of all girls and women suffer from dysmenorrhea (cramps), a dull or throbbing pain that usually centers in the lower mid-abdomen, radiating toward the lower back or thighs. Menstruating women of any age can experience cramps. While the pain may be only mild for some women, others experience severe discomfort that …
Dyspepsia can be defined as painful, difficult, or disturbed digestion, which may be accompanied by symptoms such as nausea and vomiting, heartburn, bloating, and stomach discomfort. The digestive problems may have an identifiable cause, such as bacterial or viral infection, peptic ulcer, gallbladder, or liver disease. The bacteria Helicobacter pylori is often found in those individuals suffering …
An otoscope is a hand-held instrument with a tiny light and a cone-shaped attachment called an ear speculum, which is used to examine the ear canal. An ear examination is a normal part of most physical examinations by a doctor or nurse. It is also done when an ear infection or other type of ear problem is suspected. An otoscope is used to look into the ear canal to see the ear drum. Redness or flu…
Ear surgery is the treatment of diseases, injuries, or deformations of the ear by operation with instruments. Ear surgery is performed to correct certain types of hearing loss, and to treat diseases of, injuries to, or deformities of the ear's auditory tube, middle ear, inner ear, and auditory and vestibular systems. Ear surgery is commonly performed to treat conductive hearing loss, persis…
Echinacea, or purple coneflower, is a perennial herb of the Composite family, commonly known as the daisy family. Most often referred to as the purple coneflower, this hardy plant also known as Sampson root, Missouri snakeroot, and rudbeckia. The prominent, bristly seed head inspired the generic name of the plant, taken from the Greek word echinos meaning hedgehog. Echinacea is a North American pr…
Echinococcosis (Hydatid disease) refers to human infection by the immature (larval) form of tapeworm, Echinococcus. One of three forms of the Echinococcus spp., E. granulosus, lives on dogs and livestock, and infects humans through contact with these animals. Allergic reactions and damage to various organs from cyst formation are the most common forms of disease in humans. E. granulosus is found i…
Echocardiography is a diagnostic test that uses ultrasound waves to create an image of the heart muscle. Ultrasound waves that rebound or echo off the heart can show the size, shape, and movement of the heart's valves and chambers as well as the flow of blood through the heart. Echocardiography may show such abnormalities as poorly functioning heart valves or damage to the heart tissue from…
In an ectopic pregnancy, the fertilized egg implants in a location outside the uterus and tries to develop there. The word ectopic means "in an abnormal place or position." The most common site is the fallopian tube, the tube that normally carries eggs from the ovary to the uterus. However, ectopic pregnancy can also occur in the ovary, the abdomen, and the cervical canal (the openin…
Edema is a condition of abnormally large fluid volume in the circulatory system or in tissues between the body's cells (interstitial spaces). Normally the body maintains a balance of fluid in tissues by ensuring that the same of amount of water entering the body also leaves it. The circulatory system transports fluid within the body via its network of blood vessels. The fluid, which contain…
Edwards' syndrome is caused by an extra copy of chromosome 18. For this reason, it is also called trisomy 18 syndrome. The extra chromosome is lethal for most babies born with this condition. It causes major physical abnormalities and severe mental retardation, and very few children afflicted with this disease survive beyond a year. Humans normally have 23 pairs of chromosomes. Chromosomes …
The Ehlers-Danlos syndromes (EDS) refer to a group of inherited disorders that affect collagen structure and function. Genetic abnormalities in the manufacturing of collagen within the body affect connective tissues, causing them to be abnormally weak. Collagen is a strong, fibrous protein that lends strength and elasticity to connective tissues such as the skin, tendons, organ walls, cartilage, a…
Ehrlichiosis is a bacterial infection that is spread by ticks. Symptoms include fever, chills, headache, muscle aches, and tiredness. Ehrlichiosis is a tick-borne disease caused by infection with Ehrlichia bacteria. Ticks are small, blood-sucking arachnids. Although some ticks carry disease-causing organisms, most do not. When an animal or person is bitten by a tick that carries bacteria, the bact…
Electric shock injuries are caused by lightning or electric current from a mechanical source passing through the body. Electric shocks are responsible for about 1, 000 deaths in the United States each year, or about 1% of all accidental deaths. The severity of injury depends on the current's pressure (voltage), the amount of current (amperage), the type of current (direct vs. alternating), …
Electrical nerve stimulation, also called transcutaneous electrical nerve stimulation (TENS), is a noninvasive, drug-free pain management technique. By sending electrical signals to underlying nerves, the battery-powered TENS device can relieve a wide range of chronic and acute pain. TENS is used to relieve pain caused by a variety of chronic conditions, including: The device is also effective aga…
Electrical stimulation of the brain (ESB) is a relatively new technique used to treat chronic pain and tremors associated with Parkinson disease. ESB is administered by passing an electrical current through an electrode implanted in the brain. While the implantation of electrodes in the brain is used to treat or diagnose several disorders, the term ESB is limited here to the treatment of tremors, …
Electrocardiography is a commonly used, non-invasive procedure for recording electrical changes in the heart. The record, which is called an electrocardiogram (ECG or EKG), shows the series of waves that relate to the electrical impulses which occur during each beat of the heart. The results are printed on paper or displayed on a monitor. The waves in a normal record are named P, Q, R, S, and T an…
Electroconvulsive therapy (ECT) is a medical treatment for severe mental illness in which a small, carefully controlled amount of electricity is introduced into the brain. This electrical stimulation, used in conjunction with anesthesia and muscle relaxant medications, produces a mild generalized seizure or convulsion. While used to treat a variety of psychiatric disorders, it is most effective in…
Electroencephalography, or EEG, is a neurological test that uses an electronic monitoring device to measure and record electrical activity in the brain. The EEG is a key tool in the diagnosis and management of epilepsy and other seizure disorders. It is also used to assist in the diagnosis of brain damage and disease (e.g., stroke, tumors, encephalitis), mental retardation, sleep disorders, degene…
An electrolyte disorder is an imbalance of certain ionized salts (i.e., bicarbonate, calcium, chloride, magnesium, phosphate, potassium, and sodium) in the blood. Electrolytes are ionized molecules found throughout the blood, tissues, and cells of the body. These molecules, which are either positive (cations) or negative (anions), conduct an electric current and help to balance pH and acid-base le…
Electrolytes are positively and negatively charged molecules, called ions, that are found within cells, between cells, in the bloodstream, and in other fluids throughout the body. Electrolytes with a positive charge include sodium, potassium, calcium, and magnesium; the negative ions are chloride, bicarbonate, and phosphate. The concentrations of these ions in the bloodstream remain fairly constan…
Electromyography (EMG) is an electrical recording of muscle activity that aids in the diagnosis of neuromuscular disease. Muscles are stimulated by signals from nerve cells called motor neurons. This stimulation causes electrical activity in the muscle, which in turn causes contraction. This electrical activity is detected by a needle electrode inserted into the muscle and connected to a recording…
Electronic fetal monitoring (EFM) is a method for examining the condition of a baby in the uterus by noting any unusual changes in its heart rate. Electronic fetal monitoring is performed late in pregnancy or continuously during labor to ensure normal delivery of a healthy baby. EFM can be utilized either externally or internally in the womb. The heart rate of a fetus undergoes constant adjustment…
An electrophysiology (EP) study of the heart is a nonsurgical analysis of the electrical conduction system (normal or abnormal) of the heart. The test employs cardiac catheters and sophisticated computers to generate electrocardiogram (EKG) tracings and electrical measurements with exquisite precision from within the heart chambers. The EP study can be performed solely for diagnostic purposes. It …
The word elephantiasis is a vivid and accurate term for the syndrome it describes: the gross (visible) enlargement of the arms, legs, or genitals to elephantoid size. True elephantiasis is the result of a parasitic infection caused by three specific kinds of round worms. The long, threadlike worms block the body's lymphatic system—a network of channels, lymph nodes, and organs that h…
An embolism is an obstruction in a blood vessel due to a blood clot or other foreign matter that gets stuck while traveling through the bloodstream. The plural of embolism is emboli. Emboli have moved from the place where they were formed through the bloodstream to another part of the body, where they obstruct an artery and block the flow of blood. The emboli are usually formed from blood clots bu…
Emphysema is a chronic respiratory disease where there is over-inflation of the air sacs (alveoli) in the lungs, causing a decrease in lung function, and often, breathlessness. Emphysema is the most common cause of death from respiratory disease in the United States, and is the fourth most common cause of death overall. There are1.8 million Americans with the disease, which ranks fifteenth among c…
Empyema is a condition in which pus and fluid from infected tissue collects in a body cavity. The name comes from the Greek word empyein meaning pus-producing (suppurate). Empyema is most often used to refer to collections of pus in the space around the lungs (pleural cavity), but sometimes refers to similar collections in the gall bladder or the pelvic cavity. Empyema in the pleural cavity is som…
Encephalitis is an inflammation of the brain, usually caused by a direct viral infection or a hypersensitivity reaction to a virus or foreign protein. Brain inflammation caused by a bacterial infection is sometimes called cerebritis. When both the brain and spinal cord are involved, the disorder is called encephalomyelitis. An inflammation of the brain's covering, or meninges, is called men…
Endarterectomy is an operation to remove or bypass the fatty deposits, or blockage, in an artery narrowed by the buildup of fatty tissue (atherosclerosis). Removing the fatty deposits restores normal blood flow to the part of the body supplied by the artery. An endarterectomy is performed to treat cerebrovascular disease in which there is a serious reduction of blood supply to the brain (carotid e…
The endocardium is the inner lining of the heart muscle, which also covers the heart valves. When the endocardium becomes damaged, bacteria from the blood stream can become lodged on the heart valves or heart lining. The resulting infection is known as endocarditis. The endocardium lines all four chambers of the heart—two at the top (the right and left atria) and two at the bottom (the righ…
Endometrial biopsy is a procedure in which a sample of the endometrium (tissue lining the inside of the uterus) is removed for microscopic examination. The test is most often performed to find out the cause of abnormal uterine bleeding. Abnormal bleeding includes bleeding between menstrual periods, excessive bleeding during a menstrual period, or bleeding after menopause. Since abnormal uterine bl…
Endometrial cancer develops when the cells that make up the inner lining of the uterus (the endometrium) become abnormal and grow uncontrollably. Endometrial cancer (also called uterine cancer) is the fourth most common type of cancer among women and the most common gynecologic cancer. Approximately 34, 000 women are diagnosed with endometrial cancer each year. In 1998, approximately 6, 300 women …
Endometriosis is a condition in which bits of the tissue similar to the lining of the uterus (endometrium) grow in other parts of the body. Like the uterine lining, this tissue builds up and sheds in response to monthly hormonal cycles. However, there is no natural outlet for the blood discarded from these implants. Instead, it falls onto surrounding organs, causing swelling and inflammation. This…
Endorectal ultrasound (ERUS) is a procedure where a probe is inserted into the rectum and high frequency sound waves (ultrasound waves) are generated. The pattern of echoes as they bounce off tissues is converted into a picture (sonogram) on a television screen. ERUS is used as a diagnostic procedure in rectal cancer to determine stage of the tumor and as a postradiation, presurgical examination t…
Endoscopic retrograde cholangiopancreatography (ERCP) is a technique in which a hollow tube called an endoscope is passed through the mouth and stomach to the duodenum (the first part of the small intestine). This procedure was developed to examine abnormalities of the bile ducts, pancreas, and gallbladder. It was developed during the late 1960s and is used today to diagnose and treat blockages of…
Endoscopic sphincterotomy or endoscopic retrograde sphincterotomy (ERS) is a relatively new endoscopic technique developed to examine and treat abnormalities of the bile ducts, pancreas and gallbladder. The procedure was developed as an extension to the diagnostic examination, ERCP (endoscopic retrograde cholangiopancreatography); with the addition of "sphincterotomy, " abnormalities…
An enema is the insertion of a solution into the rectum and lower intestine. Enemas may be given for the following purposes: The rectal tube used for infusion of the enema solution should be smooth and flexible to decrease the possibility of damage to the mucous membrane that lines the rectum. Tap water is commonly used for adults but should not be used for infants because of the danger of electro…
A non-cancerous condition that affects many men past 50 years of age, enlarged prostate makes urinating more difficult by narrowing the urethra, a tube running from the bladder through the prostate gland. It can be effectively treated by surgery and, today, by certain drugs. The common term for enlarged prostate is BPH, which stands for benign (non-cancerous) prostatic hyperplasia or hypertrophy. …
Enterobacterial infections are disorders of the digestive tract and other organ systems produced by a group of gram-negative, rod-shaped bacteria called Enterobacteriaceae. Gram-negative means that the organisms do not retain the violet color of the dye used to make Gram stains. The most troublesome organism in this group is Escherichia coli. Other enterobacteria are species of Salmonella, Shigell…
Enterobiasis, or pinworm infection as it is commonly called, is an intestinal infection caused by the parasitic roundworm called Enterobius vermicularis. The most common symptom of this irritating, but not particularly dangerous, disease is itching around the anal area. The pinworm of the genus Enterobius pictured above is the source of this infestation occurring in children. (Photo Researcher…
