Answer :USMLE step 2 Mcq 290:A woman in the first trimester of pregnancy has an endovaginal scan after complaining of lower abdominal pain




Correct Answer: A

The correct definition of the positive predictive value is the likelihood that a positive test result actually identifies presence of disease. The ability to identify the ABSENCE of disease is the definition of SPECIFICITY. The prevalence is the number of existing cases per 100,000 population at a target date . The ratio of number of correct positive tests with respect to the total number with disease is the definition of sensitivity . The true negative ratio is defined as TN / (TN + FP) and is called the specificity


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