See also: Thyroid Ultrasound
Technique
- Begin with diagnostic ultrasound evaluation
- ACR-TIRADS or ATA classification of thyroid nodules is helpful in determining which nodules require biopsy and which do not.
- Transverse imaging allows visualization of nodules and carotid and is generally easiest.
- Position the patient for comfort and access.
- Recumbent without uncomfortable neck extension.
- There should be a straight line between the operator, the neck, and the image screen.
- Mark the needle entry point on the skin with a marking pen. See details below on short-axis and long-axis techniques.
- Inject lidocaine with epinephrine along the anticipated needle track, 0.5 to 1.0 mL
- Consider use of color Doppler imaging to identify prominent vasculature in the expected needle path and near the target
- Place coupling gel on the probe and cover the probe with a probe cover or plastic sheet.
- Clean all coupling gel off the patient's skin.
- Have 3 standard equipment setups ready: 27Ga needle, 1.25" length, on 5cc Luer lock syringe with 2cc air in the syringe.
Short Axis Technique
Center the nodule in the image. This means the nodule is centered under the ultrasound probe.
Pass the needle through the mark while maintaining the center axis. Estimate the angle between the needle and the probe based on the depth of the target; more acute angle for deeper target.
Remember that the needle will not be visible until it reaches the imaging plane.
Long Axis Technique
Position the probe so the target is closer to the needle-entry side of the image. This shortens and steepens the needle path. There is no advantage to centering the target when using long-axis technique.
The path of the needle should be clearly visible. Make adjustments if it is not visible within ~1cm.
General Procedure
Rest the small finger of the needle hand on the patient's neck to maintain proprioception.
The bevel of the needle should remain pointed toward the transducer to increase echogenicity of needle tip.
Record and save an ultrasound video clip of the needle within the target.
Move the needle in a back-and-forth motion to obtain the specimen. Remove it if a flash becomes visible in the needle hub, or after about 5-6 seconds of movement.
Pass the needle, hub-first, to the cytopathologist.
Capillary Technique
2cc air in the syringe prior to starting the procedure
Preferred initial technique for thyroid and lymph nodes
Consider switching to 25Ga 1.5" needle if first 1-2 passes yield scant specimen
Aspiration Technique
Connect heplock tubing between needle and syringe.
The operator holds the needle hub. Once the needle reaches the target, the assistant picks up the syringe and withdraws the plunger for 1-2cc at most. Once a flash is present in the needle hub or after 5-6 seconds of back-and-forth movement, the operator requests that aspiration be released, and only after it is released the needle is withdrawn and passed to the cytopathologist.