Sputum Collection

Introduction on sputum:

Trachaebronchial secretions are often collectively referred to as sputum. Sputum is constituted by plasma, water, electrolytes and mucin. Sputum is viscoelastic, i.e., some of the properties of liquid. Chemical composition revels that sputum is 90% water and only 5% solid. The solid content increases with inflammation. It also slows exfoliation of living cells.

Sputum Collection:

· Before collecting or expectorating sputum the mouth should be prerinsed and this removes contaminants from oral cavity especially.
· For most examinations, a first morning specimen is preferred as it represents the pulmonary secretions accumulated overnight.
· The specimen should be collected in a sterile disposable, impermeable container with screw cap.
· In patients who are uncooperative or cannot produce adequate sputum, induction should be tried.
· Commonly inductants are 10% sodium chloride, acetylcyteine and sterile or distilled water aerosols.

Sputum Culture:

For routine cultures, a loopful of the sputum is inoculated onto one or two blood agar, chocolate agar, MacConkey's agar and thioglycolate broth.