FINE Needle Aspiration – FNA – Procedure and Contraindications
Puncture Fine Needle Aspiration (FNA) is done to get a sample of cells of nodules or masses for microscopic examination. This test is indicated for the evaluation of nodules, masses or palpable mass which has been visualized by previous imaging techniques. Usually, the examination is limited to superficial tumours.Nodules are found more commonly on mammary gland and the thyroid and this technique is used to take few cells out of the nodules for microscopic examination
The cells are placed on microscope slides and examined by a cytopathologist (person studying alterations in the cell).
Recent studies showed that this method gives around 75% sensitivity and specificity of over 90%. Also having a rate of false-positive results of approximately 01%, and false-negative results of 25 %.
The false-negative results are more common because the needle was not inserted directly into cancer. The needle may also have punched the wrong location of the lump or it has been inserted in the location where cancerous cells are benign.
papillocarcinoma (a type of thyroid cancer) is a tumour predominantly found in cases of false-negative cytology (cell study) of fine-needle aspiration.
The more experienced the physician performing the FNA, the lower the risk of false negative results, but these risks can not be completely discarded even if more experienced professionals are doing the FNA
FNA is a highly safe test for the evaluation of nodules especially in case of preoperative thyroid nodules.
The procedure of Fine Needle Aspiration (FNA):
First, the patient is positioned correctly and the doctor cleans the site of FNA with an antiseptic. With a disposable syringe and a thin needle is inserted in the lesion, making movements in various directions inside the nodule or mass in order to reap the maximum material, the needle is removed, and the material and put on a slide for analysis.Absolute contraindications:
Any coagulation disorder (coagulopathy, any disease that the patient bleeds more easily)Use of anticoagulants (medication that can cause unwanted bleeding as a side effect).
Relative contraindications:
Emphysematous lung (a disease that usually relates to a patient who smokes too much,), because it can cause a pneumothorax (air in the pleural cavity that is outside the lungs)Pulmonary arterial hypertension can cause haemorrhage (bleeding)
Carotid sinus tumours (bleeding may occur)
Pheochromocytoma (adrenal tumours) that can be manipulated to release adrenalin in the bloodstream, causing hypertensive crises - a sudden increase of blood pressure.
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