A diagnostic procedure in which cell samples are taken from suspicious thyroid nodules with a fine needle under ultrasound guidance to differentiate benign from malignant.
Indication
- Thyroid nodules of intermediate-high risk (TI-RADS 4-5) measuring 1 cm and above on ultrasound
- Nodules over 5 mm with highly suspicious features such as microcalcifications and irregular margins
- Growth or structural change in neck lymph nodes suggesting thyroid cancer
- Nodules detected together with rapid growth, hoarseness, or swallowing difficulty
- Evaluation of small nodules in individuals with childhood neck radiation history or family history of thyroid cancer
- Repeat of a previous insufficient (Bethesda I) biopsy or re-evaluation of a growing nodule
Preparation
- Fasting is not required; normal nutrition can be continued
- Blood thinners (warfarin, clopidogrel, novel anticoagulants) may be temporarily discontinued before the procedure with physician approval; aspirin is generally continued if needed
- Known bleeding disorders, aspirin/clopidogrel use, and allergy history should be reported before the procedure
- Previous thyroid ultrasound and blood tests (TSH, T3, T4) should be brought
- Loose clothing that leaves the neck area exposed should be worn; jewelry is removed
How it's performed
- The patient is positioned supine with the head slightly tilted backward
- The neck area is cleaned with antiseptic; local anesthesia is generally not needed, but the skin surface can be numbed if desired
- Under ultrasound guidance, the nodule is visualized and several passes are made with a 25-27 gauge fine needle, and cell samples are obtained
- During the procedure, the patient is asked not to swallow or move; each needle insertion lasts approximately 5-10 seconds
- Generally 2-4 samples are taken; samples are smeared on slides and sent to pathology, and if needed, thyroglobulin washout fluid is also collected
- The procedure takes approximately 15-20 minutes; afterward, pressure is applied to the area for 10-15 minutes
Post-procedure
- After the procedure, the patient is observed for 30-60 minutes and can return to daily life
- Pathology results are reported according to the Bethesda System: I (insufficient), II (benign), III (atypia of undetermined significance/AUS), IV (suspicious for follicular neoplasm/FN), V (suspicious for malignancy), VI (malignant)
- In Bethesda II results, ultrasound follow-up after 6-12 months is sufficient
- In Bethesda III-IV results, biopsy repeat or molecular test; in V-VI, surgical evaluation is planned
- In Bethesda I (insufficient) result, biopsy is repeated after 4-6 weeks
- Mild tenderness or bruising at the procedure site may occur for 1-2 days; rest and analgesics are sufficient
Risks
- Generally a safe procedure; serious complication rate is very low (under 1%)
- Small hematoma (bleeding) or bruise at the procedure site is the most common side effect
- Pain, tenderness, and rarely transient swallowing difficulty may occur
- Very rarely, infection or injury to neck structures has been reported
- Insufficient sampling (Bethesda I) may require repeat of the procedure
FAQ
Is FNAB painful?
Because the procedure is performed with a fine needle, it is comparable to a blood draw or slightly more uncomfortable, but is generally well tolerated. Local anesthesia can be applied to the skin if desired; most patients do not need local anesthesia.
When are results available?
Pathology results are generally ready within 5-10 business days. Your physician will interpret your result according to the Bethesda category at outpatient follow-up and plan the next step.
What happens if the biopsy result is benign?
In Bethesda II (benign) results, the probability of the nodule being malignant is very low; ultrasound follow-up at 6-12 month intervals is generally recommended. If the nodule grows or its appearance changes, a repeat biopsy may be considered.
What should I do after the procedure?
It is recommended to postpone heavy exercise and hot showers for a few hours after the procedure. If there is mild pain in the neck area, simple analgesics are sufficient. If severe pain, growing swelling, or shortness of breath occurs, contact your physician.
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