Comparison of ultrasonographic measurement of the tuberculin skin test with the result of manual reading

ABSTRACT

This study was conducted in order to determine the ultrasonographic [US] finding of tuberculin skin test and to compare with the result of manual reading. One hundred of hospital staff, in Zahedan a city in Southeast of Iran, were enrolled in this study. A 5-tuberculin unit [TU] PPD Mantoux test was administered to all healthy subjects by two experienced nurses and was applied to the left forarm. At 48 and 72 h, all PPD skin tests were measured by two independent readers and one Radiologist by High-resolution US examinations. Then results was analysed and comparison on results was made. A difference with p<0.05 was considered significant. Fifteen cases had no induration measurable either manually or by US at 48 and 72 h. At 48 and 72 h, 12, 13 cases had induration between 1-4 mm by the first reader and 11,13 had also induration between 1-4 mm as reported by the second reader. At 48 and 72 h 18, 19 cases had an induration between 5-9 mm by the first reader and at these times, 20, 23 cases had an induration between 5-9 mm by the second reader. At 48 and 72 h, 36, 35 cases had an induration between 10 to 14 by the first reader and at theses times, 35, 32 of healthy subjects had induration between 10-15 by the second reader. At 48 and 72 h, 17,15 cases, had a PPD skin test more than 15 mm, by two manual readers. On US, only 2 cases who had no induration by two readers at 48 and 72 h, showed an induration between 3.5 to 4.5 mm. There was no significant difference between reader 1 and reader 2 with US reader at 48 and 72 h [p>0.05]. Also, there was no significant difference between two manual readers at 48 and 72 h, [p = 0.1, p = 0.09]. Result showed that manual finding of TST can be simply and objectively measured in the subjects who should start prophylactic antituberculous especially in children less than 6 year who have a history of contact with tuberculous patients or in patients who should start on tuberculosis treatment immediately