Steps involved in Smear Microscopy

Sputum smears must be prepared promptly after samples are collected or received in the laboratory.

Steps in smear preparation are as follows:

1. Cleaning and Labelling of slide (No 1)
2. Making the smear (No 2-3)
3. Drying and Heat fixing the smear (No 4-5)
4. Staining and counterstaining the smear (No 6- 12)
5. Examination of slide/Reading the Smear (No 13-14)
6. Reporting and recording the observations (Digitally and TB Lab register)
7. Storage of slides (as per Laboratory Numbers in closed box) (No 15)

Figure: Steps in Smear Preparation; 1- Labelling of the slide, 2- Using a broomstick to pick up purulent portion (A) while avoiding the salivary portion (B), 3- Spreading sample on a glass slide, 4- Air-drying the slides, 5- Heat-fixing the smeared slides,6- Staining with 1% Carbol fuchsin, 7- Heating of stained smear, 8- Decolorize with 25% Sulphuric acid, 9- Rinse off decolourizer, 10- Counter stain with 0.1% Methylene blue, 11-Rinse off counter stain, 12-Drying the prepared slide, 13-14 Examination of smears , reporting of observations, 15-Storage of slides; Source: Laboratory Diagnosis by Sputum Smear Microscopy.

Resources

• Laboratory Diagnosis by Sputum Smear Microscopy - The Handbook, GLI, 2013.
• Module for Laboratory Technicians, CTD, 2005.