Test
|
Technique
|
Interpretation
|
Specific points
|
Mantoux test
|
1 TU PPD RT 23 with Tween 80
intradermally
Read after 48-72 hours (may be up-
to 7 days if +ve)
|
Induration of 10 mm or more in
largest diameter is highly suggestive
of natural infection irrespective of
BCG vaccine status
Induration of 6 mms or more than
previous test results is suggestive
of natural infection.
|
A MT positive in a child less than 2 years of age is
highly suggestive of recent infection and must be
treated. Beyond 2 years of age, a positive MT along
with history of contact, symptoms and signs and
presence of risk factors increase the risk of the
disease. In case of doubtful or inconclusive test
results, repeat test is required.
|
Repeat MT
|
Preferably on other forearm
|
BCG Test
|
–
|
–
|
BCG test is of no value & not recommended
|
|
Radiology |
|
|
|
X-ray Chest
|
Ideal X-ray Chest is taken in upright
position PA view
Well centered good exposed mid-
inspiratory film is ideal. Lateral view
is useful in case of suspicion
|
The following radiological patterns
strongly suggest a lesion diagnostic
of TB:
1. Miliary lesion
2. Unilateral Pleural effusion
3. Fibrocaseous cavitatory lesions
4. Pneumonia with enlarged media-
stinal lymph nodes.
5. Persistent pneumonia in a sympto-
matic child inspite of antibiotic
therapy.
|
Radiological lesions do not indicate etiology.
|
Repeat X-ray Chest
|
|
Deterioration or absence of clinical
improvement
In presence of good clinical
improvement
In every child.
|
After 2-3 weeks of treatment
At the end of intensive phase- 2 months
of treatment
at the end of successful treatment.
|
CT Scan Chest
|
High resolution CT Scan is preferred
|
Caseating & matted Lymph nodes on
CT Scan
|
Routine CT Scan Chest is not recommended
|
Bacteriology
|
Sputum or gastric lavage is examined
Multiple samples should be examined
Bactec method
|
Positive yeild in 30-40% of the patients
Increases yeild
Newer methods offer results in 7-10
days. No increase in the yeild
|
GOLD standard & must be attempted in all patients
Costly and not available easily
|
PCR
|
Some studies suggest use of two
probes
PCR in Pulmonary TB & in gastric
aspirate
PCR in CSF & Pleural fluid
|
Result depends on the type of gene-
ration of probe used.
Low sensitivity - as low as 20%
High sensitivity & specificity
|
Routine use of PCR not recommended
May be useful in Neurotuberculosis
|
Serology
|
Commercially available tests at present
are not ideal
|
Variable factors in host, mycobacterium
& environment makes interpretation
of these tests difficult
|
Serology is not recommended in childhood TB
|
CBC/ESR
|
–
|
These are nonspecific indicators of
inflammation
|
They have no value in diagnosis or follow up of
childhood TB
|