ULTRA-RAPID VIROLOGICAL RESPONSE (URVR): undetectable HCV RNA at Week 2 of treatment.
ULTRASONOGRAPHY (ULTRASOUND): a method of visualizing the internal parts of the body, or a fetus within the uterus, using sound waves.
UNBLINDED: see blinding.
UNCONTROLLED TRIAL: a clinical trial in which all participants receive the experimental treatment and none receive a standard treatment or placebo for comparison.
UNDETECTABLE (UNQUANTIFIABLE): a term used to describe a viral load (amount of viral RNA) that is below the level of detection of the test being used.
UNIVARIATE ANALYSIS: a statistical analysis that takes into account a single factor or variable.
UNIVERSAL PRECAUTIONS: techniques used by health-care providers (e.g., use of gloves and face masks, proper disposal of used syringes) to prevent the spread of infectious diseases.
UNOS (United Network of Organ Sharing): a non-profit organization that runs the Organ Procurement and Transplant Network which oversees the fair distribution of organs for transplantation.
