Sputum sample collection is a procedure designed to collect expectorated secretions from a patient’s lower respiratory tract. It is normally used as a laboratory specimen for the isolation of micro-organisms that might be causing infections of the respiratory tract. A first specimen obtained in the early morning before eating or drinking provides the best sputum sample. Chest physiotherapy may be helpful in mobilizing secretions just prior to sputum collection in some patients (i.e. patients with cystic fibrosis).
NICE CG 191 recommends microbiology tests, sputum collection and blood cultures (See Geeky Medics Blood Culture guide here) in all patients with moderate and high risk: CURB-65 2 or 3 (CURB-65 calculator can be found here), and in all patients with suspected tuberculosis.
This procedure causes severe coughing. Therefore it should not be performed in patients whom severe coughing may be harmful. This may include patients with the following conditions:
Haemoptysis of unknown origin
Acute respiratory distress
Unstable cardiovascular status (arrhythmias, angina, acute coronary syndrome)
Thoracic, abdominal or cerebral aneurysms
Recent thoracic, abdominal or eye surgery
Pneumothorax, pulmonary embolism
Fractured ribs or other thoracic trauma
Hypoxia (oxygen saturation <90% on room air)
Lung function impairment (FEV1 < 1.0 litre)
In order to obtain a sputum sample you will need to gather the following equipment:
Sputum specimen container and label
Biohazard bag for delivery of specimen to the laboratory
Tissue paper for the patient following cough
Investigation request form
Appropriate personal protective equipment (PPE)
Clean gloves and apron
If the patient is likely to have tuberculosis or other high-risk infection such as influenza or legionella then you will also need mask, gown and goggles.
Identify the patient as per your institution’s internal protocol. Verify their surname, forename and date of birth (DOB) and check their wrist-band, if present.
Place the patient in a comfortable, upright seated position
Collecting the Sputum Sample
Introduce yourself and your role
Check patient details (name, DOB) – confirm with details on patient wristband if applicable.
Explain the procedure. An example could be: “Hello Mr Gibson, my name is Dr Smith, we need to collect a sample from your lungs to be able to identify which bug is causing this infection in your chest. The procedure includes breathing in and out, coughing and collecting sputum in this pot. It might cause you to cough heavily straight after, but shouldn’t be too uncomfortable.”
Check the patient’s understanding of the procedure. “Do you understand everything I’ve explained? Do you have any questions?”
Obtain consent. “Are you happy for me to perform the procedure?”
Wash your hands
Have the patient rinse their mouth before coughing to remove any oral contaminants, which will be present in the patient’s saliva.
Instruct the patient to breathe in and out deeply 2 or 4 times. Then instruct them to give a series of low, deep coughs to raise sputum from the lungs. “Deep breathe in and out. Keep breathing out until you empty your lungs completely. This should trigger a deep cough and hopefully, some sputum will dislodge and come up to your mouth.”
Collect 1-2 teaspoons of sputum in the container; close and seal lid.
Follow the manufacturer’s instructions to complete the closing system.
Label the specimen container by the patient.
Complete the request form and place in a biohazard transport bag as per local policies. Ensure you report the relevant clinical history, including relevant past medical history on your request form.
Evaluate the patient’s status after the procedure, identifying red flags such as difficulty breathing or a drop in oxygen saturation.
Remove your PPE and wash your hands
Thank the patient
*Deliver sputum sample to the laboratory as soon as possible for appropriate microbiology investigations such as culture, microscopy and antibiotic sensitivity tests or molecular tests for viral infections.
If your patient has a tracheostomy or is intubated and ventilated, the procedure varies and you might need to use a suctioning device such as a suction trap. If the patient finds it difficult to expectorate, a 0.9% sodium chloride nebuliser might help loosen secretions.
Smith SF, Duell DJ, Martin BC. Clinical nursing skills. Published in 2011. [LINK]
Blakeborough L, Watson JS. The importance of obtaining a sputum sample and how it can aid diagnosis and treatment. British Journal of Nursing. Published in 2019. [LINK]
New South Wales (NSW) health. Sputum induction guidelines – Tuberculosis. Published in 2018. [LINK]
Shepherd E. Specimen collection 4: procedure for obtaining a sputum specimen. Published in 2020. [LINK]
Eccles S, Pincus C, Higgins B, Woodhead M. Diagnosis and management of community and hospital-acquired pneumonia in adults: summary of NICE guidance. Published in 2014. [LINK]