AFB STAIN, MISCELLANEOUS

The AFB (acid-fast bacilli) stain uses the Ziehl-Neelsen technique to look for tuberculosis bacteria under the microscope. This 'miscellaneous' version is for samples other than the usual sputum — body fluids, pus, discharge, tissue or other material from the site where TB is suspected.

TB does not only affect the lungs. It can involve lymph nodes, the abdomen, bones, the urinary tract and other sites — called extrapulmonary TB — and an AFB stain on a sample from the affected site is often the first laboratory step in confirming it.

When do doctors advise this test?

• Suspected TB of lymph nodes, abdomen, bones or other non-lung sites
• Pus or fluid from a long-standing swelling or sinus that is not healing
• Chronic discharge or wounds where TB is a possibility
• As a companion to TB culture or CBNAAT (GeneXpert) testing advised by your doctor

Preparation & the sample

No fasting is needed. The sample is collected from the affected site by your doctor or the laboratory team, and the correct container and quantity matter — call +91 9451155402 before submission so the team can guide you. If you have already started anti-TB treatment, mention it, as treatment reduces the chance of detecting the bacteria.

This information is educational and general. Your doctor's advice for your specific situation always comes first.