Ultrasound-Guided Fine Needle Aspirate (US-FNA)
A minimally invasive diagnostic sampling procedure using real-time ultrasound guidance to direct a fine needle into deep internal organs or masses to harvest cells for cytology.
💬 In Plain English
An ultrasound-guided fine needle aspirate (US-FNA) is a quick, safe, and minimally invasive way to sample deep internal organs or tumors without open surgery. When an ultrasound scan reveals an abnormal spot—such as a mass in the spleen, an enlarged liver, a swollen internal lymph node, or a thickened kidney—the veterinarian uses the ultrasound probe to watch a tiny needle travel in real time directly into the target tissue. Cells are gently aspirated into the syringe, transferred to glass slides, and sent to a veterinary clinical pathologist to check for cancer, infection, or inflammation.
🔬 Clinical & Technical Depth
For Vets & TechniciansFormal Clinical Definition
Real-time sonographically guided percutaneous needle aspiration biopsy (22–25 gauge) of visceral parenchyma, cavitary masses, or internal lymphadenopathy for microscopic cytologic evaluation.
Why Veterinarians Use It
Veterinarians perform US-FNA to safely sample suspicious abdominal and thoracic lesions without the morbidity or expense of invasive exploratory surgery.
Clinical Context Encountered
Recommended when abdominal ultrasound reveals splenic nodules, enlarged mesenteric lymph nodes, or liver masses.
Clinical Reference Guide (Surgical Procedure)
Aftercare & Recovery
Restricted activity for 24 hours; monitor gum color and abdomen for signs of internal bleeding; cytology results available in 2–4 days.
- •Fine needle aspirates of cavitary splenic hemangiosarcoma masses or pheochromocytomas carry risks of internal hemorrhage or hypertensive crisis; clotting profiles and careful risk assessment must precede sampling.
❓ Questions to Ask Your Veterinarian
Take these actionable questions with you to your next clinic visit or appointment:
- 1Was my pet screened for blood clotting abnormalities (platelet count and PT/PTT) before needle insertion?
- 2Were the collected cytology slides sent to a board-certified veterinary clinical pathologist?
- 3Are the findings consistent with a benign lesion, or does the pet require surgical removal (e.g. splenectomy)?
Academic & Clinical References
- ACVR Clinical Guidance on Ultrasound-Guided Interventional Procedures in Small AnimalsOrganization: American College of Veterinary Radiology (ACVR) • Accessed: 2026-01-10https://www.acvr.org