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Sputum Collection

Guidelines for Sputum Collection

Sputum should be collected for:

  • all patients (adults and older children) suspected of having pulmonary or laryngeal tuberculosis
  • patients diagnosed with extra-pulmonary TB who are coughing or who have an abnormal chest x-ray
  • patients being evaluated for a positive TB skin test who are coughing or who have an abnormal chest x-ray

Collect samples 8 - 24 hours apart

  • prior to the initiation of chemotherapy; then
  • at least monthly until direct smears are negative for acid-fast bacilli (AFB); 
  • weekly for patients who need to be released from isolation until direct smears are negative for AFB; then
  • continue to collect at least monthly and at the end of the 8-week initial treatment phase until cultures become negative.  It is very important that culture status be documented after 2 months of treatment, then
  • continue to collect monthly (especially for patients who are not on directly observed therapy) as long as the patient is able to cough and produce a suitable specimen;
  • and at the end of treatment

Specimens should be collected in either a well-ventilated area or a sputum collection booth. Health care workers collecting the sputum, regardless of the setting, must observe the appropriate infection control precautions. Collection of early morning specimens is preferred because of the overnight accumulation of secretions; however, you may collect specimens at any time for patients who have a deep cough that is readily productive. 

Collect sputum in a sterile container for processing and examination. Sputum should be collected under direct observation, at least for the first time. This is to insure that the patient is being properly coached and is giving a good coughing effort, as well as insuring that uncooperative patients are producing their own sputum for examination. 

Instruct the patient to breathe deeply and cough from deep down in the lungs. Instruct them that saliva and upper respiratory secretions are not sputum and are not acceptable specimens. For patients unable to bring up sputum, deep coughing may be induced by inhalation of an aerosol of warm, hypertonic (5%-15%) saline. 

Remember the following: For public health planning purposes, the degree of infectiousness is determined by the presence of AFB in the sputum, not in bronchial washings, tracheal aspirates, or other pulmonary specimens. The presence of AFB in specimens other than sputum is not particularly useful for determining how soon and to what extent a contact investigation needs to be done. Therefore, regardless of the decision to perform a bronchoscopy or other diagnostic procedure, sputum should still be collected at the time the diagnostic evaluation is performed.