ulcer - sore on the skin surface or on the stomach lining.
ulcerative colitis - a serious disease that causes ulcers and irritation in the inner lining of the colon and rectum.
ulnar bone - the longer of the two bones in the forearm.
ultrasound (Also called sonography.) - a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.
ultraviolet radiation - invisible rays that come from the sun. Ultraviolet radiation can damage the skin and cause melanoma and other types of skin cancer.
umbilical cord - a rope-like cord connecting the fetus to the placenta. The umbilical cord contains two arteries and a vein, which carry oxygen and nutrients to the fetus and waste products away from the fetus.
umbilical cord blood transplant - a procedure in which stem cells are taken from an umbilical cord immediately after delivery of an infant.
umbilical hernia - a weakness in the abdominal muscles.
unilateral - affecting one side of the body. For example, unilateral kidney cancer occurs in one kidney only.
upper GI (gastrointestinal) series (Also called barium swallow.) - a diagnostic test that examines the organs of the upper part of the digestive system: the esophagus, stomach, and duodenum (the first section of the small intestine). A fluid called barium (a metallic, chemical, chalky, liquid used to coat the inside of organs so that they will show up on an x-ray) is swallowed. X-rays are then taken to evaluate the digestive organs.
urea - the nitrogen part of urine produced from the breakdown of protein.
urea breath test - test used to detect Helicobacter pylori (H. pylori) infection. The test measures breath samples for urease, an enzyme H. pylori produces.
ureterocele - the portion of the ureter closest to the bladder becomes enlarged because the ureter opening is very tiny and obstructs urine outflow; urine backs up in the ureter tube.
ureteroscope - an optical device which is inserted into the urethra and passed up through the bladder to the ureter; to inspect the opening of the ureters.
ureters - two narrow tubes that carry urine from the kidneys to the bladder.
urethra - narrow channel through which urine passes from the bladder out of the body.
urethritis - an infection limited to the urethra.
urge incontinence - the inability to hold urine long enough to reach a restroom. It is often found in people who have conditions such as diabetes, stroke, dementia, Parkinson's disease, and multiple sclerosis, but may be an indication of other diseases or conditions that would also warrant medical attention.
urgent surgery (Also called emergency surgery.) - an operation performed immediately as a result of an urgent medical condition.
urinalysis - laboratory examination of urine for various cells and chemicals, such as red blood cells, white blood cells, infection, or excessive protein.
urinary incontinence - the loss of bladder control.
urinary retention - the inability to empty the bladder.
urinary tract infection (UTI) - an infection that occurs in the urinary tract; often caused by bacteria such as Escherichia coli. A urinary tract infection often causes frequent urination, pain, and burning when urinating, and blood in the urine.
urine flow study - a test in which the patient urinates into a special device that measures how quickly the urine is flowing. A reduced flow may suggest benign prostatic hyperplasia(BPH).
urogenital - refers to the urinary and reproductive systems.
urology - the branch of medicine concerned with the urinary tract in both genders, and with the genital tract or reproductive system in the male.
urticaria (Also called hives.) - a condition in which red, itchy, and swollen areas appear on the skin - usually as an allergic reaction from eating certain foods or taking certain medications.
urushiol - resin in poison ivy plants that causes an allergic skin reaction.
Usher's syndrome - A hereditary disease that affects hearing and vision.
uterine wall - the wall of the uterus.
uterus (Also called the womb.) - a hollow, pear-shaped organ located in a woman's lower abdomen, between the bladder and the rectum, that sheds its lining each month during menstruation and in which a fertilized egg (ovum) becomes implanted and the fetus develops.