Making the smear

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Making the smear
Learning Objectives
The learner will be able to

List the tools required for making a smear

Explain the steps in preparing a smear using a wooden stick and a nichrome wire loop

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Content

The National TB Elimination Programme (NTEP) has a standard procedure for sputum smear preparation, the steps for which are listed below:

The tools required for smear preparation include a clean work surface, new and clean glass slides, a discard bucket or a foot-operated bin with a plastic liner, bamboo or wooden applicator sticks or sterile wire loop, spirit lamp and a rack for drying smears.

Use new, clean, unscratched glass slides and label the slide with the laboratory serial number.
Prepare the smear in the centre of the slide covering 3 cm X 2 cm

The smear is prepared by using either a wooden stick (Figure 2) or a sterile wire loop (Figure 3).

Figure 2: Wooden stick used in smear preparation

Figure 3: Sterile wire loop used in smear preparation

Steps for Smear Preparation Using a Wooden Stick

Break the wooden stick into two halves with uneven ends.

Using the uneven end, select and pick purulent portions of the sputum specimen and transfer onto a new, clean, labelled, glass slide.

Using the wooden stick, spread the sputum evenly, in a continuous rotational movement, to cover two-thirds of the central portion of the slide. Smear preparation should be done near a flame. This is required as approximately 6 inches around the flame is considered as a sterile zone which coagulates the aerosols raised during smear preparation.
Discard the used wooden sticks in the discard bucket or a foot-operated bin with a liner and disinfectant. A different broomstick is used for each smear so that one patient's sputum is not mixed with another patient's sputum.

Air-dry the smear slide on the rack for 30 minutes
After air-drying, heat-fix the smear, using a lighted spirit lamp.

Steps for Smear Preparation Using a Wire Loop

Take a nichrome wire loop or a disposable loop.

Using the loop, select and pick purulent portions of the sputum specimen and transfer onto a new, clean, labelled, glass slide.
Using the loop, spread the sputum evenly, in a continuous rotational movement, to cover two-thirds of the central portion of the slide.