Does anyone know what a positive tb test looks like ?
Induration greater than 10mm is considered positive. The induration is measured across the width of the arm. To measure the induration, the area is palpated and marked with ink and then measured with a flexible ruler. The redness around the induration is also measured. An induration is a slightly raised hard lump around the area where the test was given. Once a person has a positive TB skin test, they should never have another one given. This test could cause permanent scarring in that person so a chest xray is recommended instead.
