Appendix 7. Lymph node fine needle aspiration

Update: October 2023

Fine needle aspiration (FNA) is used to obtain specimens from lymph nodes in order to perform Xpert assays.

When Xpert assays are not available, smear microscopy may be perfromed. However lymph node specimens are paucibacillary and sensitivity of smear microscopy is low [1] Citation 1. Tadesse M, et al. GeneXpert MTB/RIF Assay for the Diagnosis of Tuberculous Lymphadenitis on Concentrated Fine Needle Aspirates in High Tuberculosis Burden Settings. PLoS One. 2015 Sep 14;10(9):e0137471.
https://doi.org/10.1371%2Fjournal.pone.0137471 .

7.1 Specimen collection

Equipment

• Gloves
• Sterile needle 23G (in very few cases, 19G can be used)
• Sterile 5-10 ml syringe
• 10% povidone iodine
• Sterile gauze

Technique

• Explain the procedure to patient. Position the patient comfortably (according to the location of the lymph node, sitting or lying down).
• Disinfect the skin over and around the lymph node.
• Attach the needle to the syringe and remove the needle cap.
• Maintain the lymph node stable with one hand.
• With the other hand, insert the needle deep into the lymph node mass.
• Aspirate and move the needle in a to-and-fro fashion so that material enters the needle.
• When blood or material appears in the needle hub, stop the aspiration. Try to aspirate as much material as possible into the needle hub to increase the possibility of a positive result.
• Release the negative pressure before pulling the needle out of the lymph node. Do not continue aspirating while removing the needle. This avoids aspirating materiel into the barrel of the syringe and mixing the specimen with peripheral blood from the skin.

7.2 Specimen preparation for Xpert assay

See Appendix 1.

7.3 Specimen preparation for smear microscopy

• Place a small drop of material on a slide.
• Make a smear that is neither too thin nor too thick.
• Allow to air dry.
• Fix the smear by flame when completely dry.
• Perform Ziehl-Neelsen staining.

For staining and reading, see Appendix 4.