Fine Needle Aspiration Cytology (FNAC)

Overview

Fine needle aspiration cytology (FNAC) is used to take cells from palpable nodules in organs or tissues. The purpose of this examination is to categorise the type of lesion responsible for its occurrence.

Procedure

Cells are harvested by aspiration, using a thin needle attached to a syringe and placed in a special handle, making it easier to manoeuvre.

FNAC is performed by an anatomical pathologist assisted by an anatomical pathology technician. It is ideally done with the patient lying down and does not require anaesthetic. In some cases, a topical anaesthetic spray may be used.

The test is very straightforward. Most patients experience only mild discomfort, comparable to an injection, during the procedure.

In what situations is a FNAC carried out?

It is always for the doctor to decide whether there is a need for a particular test, depending on the individual characteristics of each patient and their specific complaints or illness.

Generally, any palpable nodule can be subjected to aspiration cytology, as long as its size and location makes the procedure viable.

The aim of this procedure is to make a diagnosis and provide guidance on treatment.

Duration

A FNAC takes only a few minutes to carry out. A single puncture is usually enough to harvest sufficient material for analysis, but in some cases two or more punctures may be necessary. A brief assessment of the sample is carried out during the procedure, but in some cases more cells may need to be obtained in order to reach a diagnostic conclusion.

Preparation

No preparation is necessary to carry out a FNAC.

It should not be done on an empty stomach. After the examination, patients may resume their normal activities.

Limitations

FNAC is an examination that provides high diagnostic accuracy, but like all diagnostic tests it can sometimes give false negative and false positive results.

Therefore, results should always be taken as a part of the whole clinical assessment and interpreted in conjunction with the results of any other complementary examinations that may be relevant in each case.

The results of the FNAC are directly related to a careful selection of cases where punctures will be carried out, as there are certain conditions in which cytology does not add value to a diagnosis.

The following factors can influence the potential for diagnosis using this technique:

  • The experience of the person carrying out the FNAC;
  • The availability of additional diagnostic methods that can be applied to the samples obtained (immunocytochemistry, flow cytogenetics or molecular techniques).

Risks

Most patients experience only mild discomfort during the test. They can occasionally experience pain, especially where there are pre-existing painful injuries or in particularly sensitive locations.

There may be bleeding with subsequent slight bruising. Very rarely, there may be a vasovagal reaction (feeling of faintness).