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Fine-Needle Sampling for Cytopathologic Analysis: Lung 1113

• Freehand technique: hold transducer in ○ Apply suction to syringe three to four Pearls
nondominant hand, and insert needle with times while gently advancing and retract- • The nonsuction technique is often attempted
VetBooks.ir • Without syringe suction (nonaspiration ○ Release suction before withdrawing needle • The suction technique is useful for aspirates
ing needle.
dominant hand.
first, and if a noncellular sample is obtained,
the suction technique is then performed.
from animal.
technique)
○ Attach a 6-mL syringe preloaded with
4-5 mL of room air to 22- or 25-gauge ○ Disconnect syringe from needle. of less vascular structures (e.g., lymph node)
but often results in hemodilution when
○ Retract plunger to fill syringe with air,
needle. and reconnect syringe to needle. aspirating vascular organs such as the spleen.
○ Introduce needle parallel to plane of ○ Expel contents onto microscopic slide(s) • Cells may dry and clot in the needle very
ultrasound beam, visualizing needle as it immediately, and lightly smear using quickly. When the needle is withdrawn, the
is advanced. standard technique. expulsion of needle contents onto a micro-
○ Slowly fan transducer side to side to • Multiple samples of each organ or lesion scope slide and the slide smearing technique
identify entire needle length to tip. should be obtained, using a new needle for should be completed within seconds.
○ Rapidly advance and retract needle 3-4 each procedure. • Obtaining an FNA of an organ may be chal-
times (poke tissue) to fill needle shaft with lenging if large-volume effusion is present. In
cells. Do not move needle in any direction Postprocedure those cases, surgical or laparoscopic biopsy Procedures and Techniques
except in and out. Scan to evaluate for hemorrhage (uncommon may be preferred.
○ Withdraw needle from animal and complication).
expel contents onto microscopic slide(s) SUGGESTED READING
immediately. Lightly smear using standard Alternatives and Their Mattoon JS, et al: Ultrasound-guided aspiration and
technique. Relative Merits biopsy procedures. In Mattoon JS, et al, editors:
• With syringe suction (true aspiration Tissue-core and surgical biopsy are more Small animal diagnostic ultrasound, ed 3, St. Louis,
technique) invasive but produce larger tissue samples. 2015, Elsevier, pp 50-77.
○ Attach empty 6-mL syringe to needle. AUTHOR: Wendy D. Fife, DVM, MS, DACVR
○ Introduce needle parallel to plane of EDITORS: Leah A. Cohn, DVM, PhD, DACVIM; Mark S.
ultrasound beam, as described. Thompson, DVM, DABVP

Video
Fine-Needle Sampling for Cytopathologic Analysis: Lung Available

Difficulty level: ♦♦ • Clippers and disinfectant for skin and glass slide preparation equipment on
• Sterile 22-gauge needle × 3; 1- to 1.5-inch hand.
Synonyms length is typical to reach the lesion depth • Have emergency supplies available for the rare
Fine-needle aspiration (FNA) of the lung, lung • Sterile syringe, 6 to 12 mL, ideally with complication of significant pneumothorax
aspirate, fine-needle lung sampling Luer-Lok (p. 1164).
• Microscope glass slides (6-10) and a tray to
Overview and Goal hold them Possible Complications and
Minimally invasive, safe, rapid technique to • Pencil or marker (for slide identification) Common Errors to Avoid
provide cells from lung lesions for cytopatho- • Appropriate Romanowsky-type stain (e.g., • Although generally safe, discuss possible
logic diagnosis Diff-Quik) if immediate staining is desired complications with pet owner and obtain
• Microscope, optimally with 4×, 10×, 20×, informed consent. Patients with diffuse
Indications and a higher objective (50× or 100× oil pulmonary disease may be at increased
Best suited for sample collection from nodules objective) risk for clinically decompensating after
or consolidated lesions toward the periphery • Optional: unstained slides may be submit- the procedure. Hemorrhage (hemothorax
of the lung but can be used in animals with ted to an outside laboratory for review by [p. 436]), hemoptysis, external hemor-
heavy, diffuse pulmonary infiltrates a clinical pathologist rhage, pneumothorax (p. 797), seeding of
• Optional: fluid may be submitted for malignant cells, and rupture of pulmonary
Contraindications microbial culture or cytocentrifugation abscess (p. 5) are the most serious potential
• Coagulopathy concentration for cytopathologic evaluation complications. Pet owners should also be
• Bullae warned that the technique may not provide a
• Marked pulmonary hypertension (p. 838) Anticipated Time diagnosis.
• Lesion too deep in the chest or adjacent to Actual sample collection and processing time • The needle should be inserted just in front
organs such as the heart or great vessels < 15 minutes; longer if anesthesia or direct of a rib to avoid intercostal vessels.
imaging guidance is used • Avoid placing needle into or through the
Equipment, Anesthesia diaphragm. It is not uncommon for clinical
Does not require anesthesia, but animal must Preparation: Important Checkpoints pathologists to receive slides with liver tissue
be restrained and should not be in marked • Select appropriate needle size and length from FNA of the lung.
respiratory distress at time of sampling. Sedation depending on predetermined (by imaging • If blood is seen in the needle/syringe during
or anesthesia can facilitate safe sampling when studies, such as thoracic radiographs) location aspiration, immediately withdraw the needle
movement is an issue or if imaging studies of the lung mass. from the thorax.
(ultrasound [US], computed tomography [CT]) • Have necessary collection (including US • Excessive vacuum pressure during needle
are used to guide collection of aspirates. machine, if planning to use US guidance) aspiration (cells may lyse)

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