Question
Which among the following is true about the test shown in the photograph below?
A. < 5 cm always +ve.
B. Usually negative after treatment.
C. Positive reaction in children < 2 yrs is not important than adult.
D. Usually read after 48 – 72 hours.
Show Answer
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Correct Answer » D
Explanation
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The test shown in the photograph above represents Mantoux test.
After intradermal injection of PPD in to flexor aspect of forearm, the site is examined 48-72 hours later and induration measured.
About other options
Option ‘a’
- Induration of 10 mm → Positive
- Induration of . 5 mm→ Negative
- Induration 6-9 mm→ Equivocal
Option ‘b’
- A positive tuberculin test may occasionally (Not usually) revert to negative on INH treatment – Park 19th/e Option ‘c’
- A positive tuberculin test has more significance in children than adults.
- If a child below 2 years is found to be tuberculin positive, it is an indirect evidence of an active tuberculous lesion in the body even if it is not manifest.
Option `c’
- In post measles state, it may be false negative (not false postive).
