A fine needle aspiration biopsy (FNAB) is a diagnostic medical procedure that collects a small sample of cells or fluid from a suspicious area. This minimally invasive technique involves inserting a very thin, hollow needle into the abnormal tissue or mass. The collected material is then sent to a laboratory for microscopic examination by a pathologist.
What Does FNAB Diagnose?
Fine needle aspiration biopsy is commonly employed to investigate various suspicious lumps, masses, or abnormalities detected through physical examination or imaging studies. It helps determine the nature of growths found in accessible areas such as the thyroid gland, lymph nodes, breast tissue, or salivary glands. The primary goal is to ascertain if a mass is benign, meaning non-cancerous, or malignant, indicating the presence of cancer. Beyond identifying cancerous cells, FNAB can also help diagnose other conditions, including infections or inflammatory processes. For instance, it can detect the presence of pus in an abscess or specific inflammatory cells. This procedure offers a less invasive alternative to open surgical biopsies. Doctors often recommend an FNAB when they need to quickly assess a newly discovered or changing lesion.
The FNAB Procedure Explained
Before an FNAB, patients are typically advised to inform their doctor about any medications they are taking, especially blood thinners, as these might need temporary adjustment. During the procedure, the patient is positioned comfortably, often lying down, to allow easy access to the biopsy site. The skin over the area is thoroughly cleaned with an antiseptic solution to prevent infection. For larger or more sensitive masses, a local anesthetic may be injected to numb the skin and surrounding tissue, minimizing discomfort during needle insertion.
To precisely guide the needle, the physician may use imaging techniques such as ultrasound or computed tomography (CT) scans, particularly for deeper or smaller lesions. A very fine, hollow needle is then inserted through the skin and into the mass. Gentle suction is applied through a syringe attached to the needle, aspirating cells and fluid into the needle. Multiple passes, typically two to six, might be made to ensure an adequate and representative sample is collected from different parts of the lesion. In some cases, a cytopathologist may be present during the procedure to quickly assess the sample’s adequacy, reducing the need for repeat biopsies. Patients usually feel a sensation of pressure or a brief, sharp prick as the needle enters, but severe pain is generally not experienced.
After Your FNAB
Immediately following a fine needle aspiration biopsy, direct pressure is applied to the biopsy site for several minutes to help prevent bruising and bleeding. A small bandage is then placed over the area. It is common to experience mild bruising, tenderness, or slight swelling at the biopsy site for a day or two after the procedure. These sensations are generally temporary and resolve on their own.
Patients are usually advised to avoid strenuous activities, heavy lifting, or vigorous exercise for at least 24 hours to allow the site to heal properly. Any mild discomfort can typically be managed with over-the-counter pain relievers, such as acetaminophen. While complications are uncommon, it is important to monitor the biopsy site for any concerning signs. Patients should contact their doctor if they experience excessive bleeding, increasing pain that is not relieved by medication, or signs of infection such as spreading redness, warmth, pus, or a fever.
Interpreting Your FNAB Results
The results from a fine needle aspiration biopsy typically become available within a few days to about a week, though this can vary depending on the laboratory and the complexity of the analysis. The pathologist prepares a detailed report outlining their findings.
The results usually fall into one of several categories. A “benign” result indicates that no cancerous cells were identified in the sample. A “malignant” result confirms the presence of cancerous cells. Sometimes, the report may state “atypical” or “suspicious,” meaning the cells show some abnormal features but are not definitively cancerous, often necessitating further investigation. Lastly, a result might be “non-diagnostic” or “inadequate sample,” indicating that not enough cells were obtained for a conclusive diagnosis, which may require a repeat FNAB or another type of biopsy. Your healthcare provider will discuss these results with you and recommend the appropriate next steps, which could include monitoring, additional tests, or treatment options.