The purpose of sputum examination is to determine whether TB bacteria are present. You will need to collect three sputum samples (also called specimens) from each person with suspected TB for this purpose, as follows:
- First, explain to the TB suspect the reason for sputum examination and ask for his/her cooperation
- Then explain that examining sputum under a microscope is the best way to determine the presence of TB bacteria in the lungs
- Collect three sputum specimens from the TB suspect and write his or her name on the specimen containers (a small plastic bottle with a lid to prevent the spilling of the specimen while being transported to the laboratory).
How to collect sputum samples
You need three sputum containers on which the name of the suspect is to be written. Do not write the person's name on the lid as this can cause confusion in the laboratory. Before you begin, explain to the person what collecting a specimen involves, and where possible guide him/her through the process. Begin by giving the person the container, then:
- Ask the person to open the lid and, holding the container like a glass of water, to take a deep breath and then cough out sputum (not saliva) into the container, without allowing sputum to spill on the edge or side of the container.
- Ask the person to put the lid on the container tightly.
- This first sample is collected 'on the spot'. Keep the specimen in a safe place away from children, heat or sunlight. Heat or sunlight can kill the TB bacteria in the specimens (figure below).
- Give the person another labelled container to take home and collect a specimen immediately after waking up the next morning.
- Explain to the person that before collecting this second specimen, he or she should rinse their mouth with water so that food or any other particles do not contaminate the specimen. This second specimen is the 'early morning specimen'. It is important to tell TB suspects to bring this second specimen with them when they come back to you the following day.
- When the person comes back with their 'early morning' specimen the following day, take the third specimen 'on the spot'
A woman hands over her sputum sample to a health professional (Photo: courtesy of the Lung Health Image Library, World Lung Foundation).
The following box summarises the key action points involved in collecting sputum for TB case finding.
Important points to remember about sputum collection
- Use three containers labelled with the person's name; do not write the name on the lids.
- Collect specimens in an open area or a well ventilated room
- Check that the lid is tightly closed after the specimen is collected
- Wash your hands with soap and water after handling the container
- Ensure that three specimens are collected and kept safely before sending them to the laboratory
- Send the specimens with a request form to the nearest laboratory for examination.
- Tell the TB suspect when to come back for the laboratory result
- If the sputum is positive and the person does not come back to hear the result, then trace him or her as soon as possible, and explain the outcome and refer them for treatment. Treatment needs to be started immediately to prevent the spread of TB.