How To Perform Fine Needle Aspiration of Thyroid

• Indications:
o Evaluation of palpable thyroid masses
o Differentiation of benign from malignant thyroid lesions.

• Contraindications:
None

• Anesthesia:
Anesthesia is not routinely used for FNA. However, if needed, a small amount of 1% lidocaine may be infiltrated locally, taking care not to distort the palpable lesion.

• Equipment:
o Alcohol prep
o 10-ml syringe
o 1/2-inch 25-gauge needle
o Syringe holder (optional)
o Glass microscope slides (two)
o Spray fixative, gauze
o In many situations, it may be preferable to have a cytopathologist present.

• Positioning:
The patient is placed in a supine position, and a roll is placed behind the shoulders to allow for neck extension and to bring the lesion closer to the surface.

• Technique:
o Prep the area for aspiration with an alcohol prep pad as if for phlebotomy.
o Palpate the lesion and immobilize the mass between the fingertips of the nondominant hand.
Using the dominant hand, advance a 25-gauge needle with an attached 10-ml syringe into the lesion. The needle should be directed medially, toward the trachea.
o Note the consistency of the mass upon entering it with the needle (firm, soft, rubbery, doughy, gritty).
o Once the lesion is entered, a full 10 ml of suction is applied to the syringe. In a variant of this procedure, the nonsuction technique, no negative pressure is applied to decrease local trauma and bleeding.
o While maintaining suction (if used), move the needle back and forth through the lesion several times in different directions.
o Release the syringe plunger and allow it to return to a neutral position prior to removing the needle from the lesion. In the nonsuction technique, the plunger will already be in neutral
position. At this point the specimen is within the needle and hub and should not be in the syringe.
o Remove the needle from the patient, and have the patient apply pressure to the puncture site with a gauze pad.
o Detach the needle from the syringe.
o Fill the syringe with air.
o Reattach the needle onto the syringe.
o Touch the needle tip to a glass microscope slide with the bevel at a 458–908 angle to the slide surface.
o Expel material within the needle onto the slide.
o Make a smear by using a second glass slide to gently press down and draw out the material to a feathered edge. If the material is more liquid, it is pulled in the same fashion as a blood smear, except that before the feathering process is completed, the spreading slide is raised, leaving a line of particles across the slide. The spreading slide is then turned and again pressed down against the line of particles and drawn out into a feathered edge.
o Air dry or apply cytological fixative to the slide per the protocol of the cytopathology laboratory that will be processing the specimen. (If a fixative is applied, it must be applied very quickly, usually within seconds of preparing the smear.)
o Most cytopathologists require 3–6 needle passes (samples) for an adequate pathological diagnosis.
o If a cyst is aspirated, the cyst fluid should be sent for cytology. The region of the cyst should then be re-examined; if a residual mass is felt, it should then undergo FNA.

• Complications and Management:
o Bleeding and hematomas
Thyroid punctures may produce significant hematomas and ecchymoses.
Apply firm direct pressure to puncture sites immediately following aspiration.
o Tracheal puncture
If the trachea is entered, the suction in the syringe will be lost, and the aspiration will need to be repeated.
Puncture is usually of no consequence due to the small gauge of the needle.
o Infection
Extremely rare in FNA but has been reported
Antibiotics as appropriate
Incision and drainage as necessary