The Thyroid FNAC Procedure
Fine needle aspiration cytology (FNAC) is a quick biopsy that samples cells from a thyroid nodule to check for cancer. It is the standard first-line test for suspicious nodules.
This page explains exactly what happens during the procedure and how to prepare.
Last medically reviewed: 15 November 2025
Before the procedure
Little preparation is needed. You can usually eat and drink normally and take your regular medication, including thyroid tablets. Tell the operator if you take blood thinners or have a bleeding disorder.
The nodule is first located with ultrasound so the needle is guided precisely.
During the procedure
The skin over the neck is cleaned. A very thin needle is passed into the nodule, often several times, while gentle suction draws cells into a syringe. The whole procedure usually takes only a few minutes.
Most people feel brief pressure or a mild pinch rather than real pain. Local anaesthetic is often unnecessary.
After the procedure
A small dressing is applied and you can usually resume normal activities straight away. Mild bruising or soreness at the site is common and settles quickly.
The sample is sent to a laboratory, where a pathologist examines the cells and issues a report — usually within a few days.
Understanding the result
Results are reported using the Bethesda system, from non-diagnostic through benign, indeterminate, suspicious and malignant. Most nodules turn out to be benign.
An indeterminate result may mean surgery is needed for a definitive answer. Always have the report interpreted by a clinician alongside your ultrasound findings.
Frequently asked questions
Is FNAC painful?
Most people feel only brief pressure or a mild pinch. It is a quick procedure and serious complications are rare.
How long does a thyroid FNAC take?
The actual sampling usually takes just a few minutes, though the whole appointment including preparation and ultrasound may take longer.
When will I get the result?
Cytology reports are typically available within a few days. Your clinician will explain what the result means and whether any further action is needed.
References & further reading
This page is based on established medical knowledge and guidelines from authoritative sources. Always consult a qualified clinician for personal medical advice.
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