Definition Recurrent miscarriage is defined as three or more miscarriages of a fetus before 20 weeks of gestation (i.e., before the fetus can live outside the womb). Description Also referred to as spontaneous abortion, miscarriage occurs in 15-20% of all conceptions. The majority of miscarriages occur during the first trimester. The number of previous miscarriages does not affect subsequent...

Definition Rectal prolapse is protrusion of rectal tissue through the anus to the exterior of the body. The rectum is the final section of the large intestine. Description Rectal prolapse can be either partial or complete. In partial prolapse, only the mucosa layer (mucous membrane) of the rectum extends outside the body. The projection is generally 0.75-1.5 in (2-4 cm) long....

Definition Rectal polyps are tissue growths that arise from the wall of the rectum and protrude into it. They may be either benign or malignant (cancerous). Description The rectum is the last segment of the large intestine, ending in the anus, the opening to the exterior of the body. Rectal polyps are quite common. They occur in 7-50% of all people, and in two thirds of people over age...

Definition Rectal examination or digital rectal examination (DRE) is performed by means of inserting a gloved, lubricated finger into the rectum and palpating (feeling) for lumps. Purpose DRE is used as a screening tool to locate rectal cancer and prostate cancer. It is also used as a diagnostic test to find non-cancerous abnormalities within the rectum like hemorrhoids, anal...

Definition The rectum is the portion of the large bowel that lies in the pelvis, terminating at the anus. Cancer of the rectum is the disease characterized by the development of malignant cells in the lining or epithelium of the rectum. Malignant cells have changed such that they lose normal control mechanisms governing growth. These cells may invade surrounding local tissue or they may spread throughout...

Definition Recompression treatment is the use of elevated pressure to treat conditions within the body after it has been subjected to a rapid decrease in pressure. It also includes hyperbaric oxygen therapy. Purpose Recompression treatment is used to overcome the adverse effects of gas embolism and decompression sickness (sometimes called the bends) in underwater divers...

Definition Rat-bite fever refers to an infection which develops in a person after being bitten or scratched by an infected animal. Description Rat-bite fever occurs most often among laboratory workers who handle lab rats in their jobs, and among people who live in poor conditions, with rodent infestation. Children are particularly likely to be bitten by rodents infesting their home and are,...

Definition The popular term for a group of spots or red, inflamed skin that is usually a symptom of an underlying condition or disorder. Often temporary, a rash is only rarely a sign of a serious problem. Description A rash may occur on only one area of the skin, or it may cover almost all of the body. Also, a rash may or may not be itchy. Depending on how it looks, a rash may be described as having the following...

Definition The various definitions of rape range from the broad (coercing a person to engage in any sexual act) to the specific (forcing a woman to submit to sexual intercourse). The United States Code includes the crime of rape under the more comprehensive term "sexual abuse."...

Definition Radioactive implants are devices that are placed directly within cancerous tissue or tumors, in order to deliver radiation therapy intended to kill cancerous cells. The practice of internal radiation therapy also is referred to as brachytherapy. Purpose With the use of radioactive implants, the tumor is subjected to radioactive activity over a longer period...

Definition Radical neck dissection is a surgical operation used to remove cancerous tissue in the head and neck. Purpose The purpose of radical neck dissection is to remove lymph nodes and other structures in the head and neck that are likely or known to be malignant. Variations on neck dissections exist, depending on the extent of the cancer. A radical neck dissection removes...

Definition Radiation therapy, sometimes called radiotherapy, x-ray therapy radiation treatment,cobalt therapy, electron beam therapy, or irradiation uses high energy, penetratingwaves or particles such as x rays, gamma rays, proton rays, or neutron rays to destroy cancer cells or keep them from reproducing. Purpose The...

Definition Radiation injuries are caused by ionizing radiation emitted by sources such as the sun, x-ray and other diagnostic machines, tanning beds, and radioactive elements released in nuclear power plant accidents and detonation of nuclear weapons during war and as terrorist acts. Description Ionizing radiation is...

Definition Radial keratotomy (RK) is a type of eye surgery used to correct myopia (nearsightedness). It works by changing the shape of the cornea-the transparent part of the eye that covers the iris and the pupil. Purpose About 25-30% of all people in the world are nearsighted and need eyeglasses or contact lenses for distance vision to be clear. For a number of reasons, some people don't...

Definition Rabies is an acute viral disease of the central nervous system that affects humans and other mammals but is most common in carnivores (flesh-eaters). It is sometimes referred to as a zoonosis,or disease of animals that can be communicated to humans. Rabies is almost exclusively transmitted through saliva from the bite of an infected animal. Another name...

Definition Radiation injuries are caused by ionizing radiation emitted by sources such as the sun, x-ray and other diagnostic machines, tanning beds, and radioactive elements released in nuclear power plant accidents and detonation of nuclear weapons during war and as terrorist acts.  Description Ionizing radiation is made up of unstable atoms that contain an excess amount of energy. In an attempt to...

Definition Radial keratotomy (RK) is a type of eye surgery used to correct myopia (nearsightedness). It works by changing the shape of the cornea–the transparent part of the eye that covers the iris and the pupil. Purpose  About 25–30% of all people in the world are nearsighted and need eyeglasses or contact lenses for distance vision to be clear. For a number of reasons, some people don’t...

Definition Rabies is an acute viral disease of the central nervous system that affects humans and other mammals but is most common in carnivores (flesh-eaters). It is sometimes referred to as a zoonosis, or disease of animals that can be communicated to humans. Rabies is almost exclusively transmitted through saliva from the bite of an infected animal. Another name for the disease is hydrophobia, which literally...

A rash is a temporary eruption of the skin. Typical situations include some of the communicable and infectious diseases, pellagra, certain skin diseases, reactions to certain drugs, and some allergies. Careful observation of a rash and of the circumstances under which it appeared helps to determine the cause of the difficulty. Certain terms are used in connection with skin lesions, as follows: Erythema. A redness...

Protrusion of the lining of the rectum occurs chiefly in infants and in elderly persons. The immediate cause is straining at stool or (in the more serious cases) merely coughing or engaging in muscular exertion as lifting. The condition becomes serious if the tissue is allowed to remain in the prolapsed condition long enough for it to be damaged from reduced blood supply. The tissue may be returned...