MODULE B
Annex B. Procedures for Obtaining Sputum Specimens in Children (Ref: Guidance for National TB Programmes on the Management of TB in Children, WHO/HTM/TB/2006.371; WHO/FCH/ CAH/2006.7)
Procedures for obtaining clinical samples for smear microscopy This annex reviews the basic procedures for the more common methods of obtaining clinical samples from children for smear microscopy: expectoration, gastric aspiration and sputum induction.
A. Expectoration Background All sputum specimens produced by children should be sent for smear microscopy and, where available, mycobacterial culture. Children who can produce a sputum specimen may be infectious, so, as with adults, they should be asked to do this outside and not in enclosed spaces (such as toilets) unless there is a room especially equipped for this purpose. Procedure (adapted from Laboratory services in tuberculosis control. Part II. Microscopy (1)) 1. Give the child confidence by explaining to him or her (and any family members) the reason for sputum collection. 2. Instruct the child to rinse his or her mouth with water before producing the specimen. This will help to remove food and any contaminating bacteria in the mouth. 3. Instruct the child to take two deep breaths, holding the breath for a few seconds after each inhalation and then exhaling slowly. Ask him or her to breathe in a third time and then forcefully blow the air out. Ask him or her to breathe in again and then cough. This should produce sputum from deep in the lungs. Ask the child to hold the sputum container close to the lips and to spit into it gently after a productive cough. 4. If the amount of sputum is insufficient, encourage the patient to cough again until a satisfactory specimen is obtained. Remember that many patients cannot produce sputum from deep in the respiratory tract in only a few minutes. Give the child sufficient time to produce an expectoration which he or she feels is produced by a deep cough. 5. If there is no expectoration, consider the container used and dispose of it in the appropriate manner.
B. Gastric aspiration Background Children with TB may swallow mucus which contains M. tuberculosis. Gastric aspiration is a technique used to collect gastric contents to try to confirm the diagnosis of TB by microscopy and mycobacterial culture. Because of the distress caused to the child, and the generally low yield of smear-positivity on microscopy, this procedure should only be used where culture is available as well as microscopy. Microscopy can sometimes give false-positive results (especially in HIV-infected children who are at risk of having nontuberculous mycobacteria). Culture enables the determination of the susceptibility of the organism to anti-TB drugs. Gastric aspirates are used for collection of samples for microscopy and mycobacterial cultures in young children when sputa cannot be spontaneously expectorated nor induced using hypertonic saline. It is most useful for young hospitalized children. However, the diagnostic yield (positive culture) of a set of three gastric aspirates is only about 25–50% of children with active TB, so a negative smear or culture never excludes TB in a child. Gastric aspirates are collected from young children suspected of having pulmonary TB. During sleep, the lung’s mucociliary system beats mucus up into the throat. The mucus is swallowed and remains in the stomach until the stomach empties. Therefore, the highest-yield specimens are obtained first thing in the morning. Detect Cases of MDR-TB
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