Fine‐needle aspiration of cutaneous, subcutaneous, and intracavitary masses in dogs and cats using 22‐ vs 25‐gauge needles

Abstract

Background Fine‐needle aspiration (FNA) is a common procedure as a diagnostic tool in veterinary medicine. However, it is unclear whether the gauge of the needle affects the quality of cytology. Objective This study compared the quality of cytologic samples obtained via FNA using 22‐ or 25‐gauge needles. Methods Fine‐needle aspiration was performed on 50 masses (cutaneous, subcutaneous, or intracavitary) obtained from client‐owned animals. The size of the needle was randomly assigned using either of the following two sequences: 22‐25‐22 gauge or 25‐22‐25 gauge. Samples were evaluated by two board‐certified clinical pathologists to assess cellularity, blood contamination, amount of cellular debris, degree of cellular trauma, and the overall ability to make a diagnosis for each sample. Results No significant difference was detected between the 22‐ and 25‐gauge needle samples for cellularity, whereas a significant difference was present for blood contamination, amount of cellular debris, and degree of cellular trauma. The overall ability to make a diagnosis was not significantly affected by the needle gauge. The degree of cellular trauma was significantly increased in intracavitary samples. Conclusions and Clinical Relevance Needle gauge is a contributing factor to FNA sample quality. However, it did not affect the overall ability to make a diagnosis. Samples obtained using 25‐gauge needles resulted in less blood contamination yet increased cellular trauma compared to 22‐gauge needle samples.

A comparison of cytologic quality in fine‐needle specimens obtained with and without aspiration from superficial lymph nodes in the dog

“…These sporadic incompatibilities may be attributed to the slight cytologic variation between different LNs and are not expected to be of appreciable clinical relevance. We evaluated cytologic quality and cytologic diagnoses by FNA versus FNNA separately in dogs with multi-centric lymphoma because it is commonly thought that lymphoblasts are more fragile and tend to rupture more easily compared to small, well-differentiated lymphocytes during sampling and smear preparation (Cowell et al 2003, Arai et al 2019. However, we failed to substantiate any appreciable difference between the two techniques in dogs with lymphoma.…”

“…In two studies of veterinary practitioners, FNAs of cutaneous masses and LNs were performed using 2-or 5-mL syringes in combination with 21-Gauge or 23-Gauge needles (Bowlt et al 2014, Amores-Fuster et al 2015. Recently, the impact of needle gauge (22-Gauge versus 25-Gauge) was investigated in the context of FNNA of canine and feline (sub)cutaneous or intracavitary masses (Arai et al 2019). Needle gauge was not associated with cellularity or the ability to make a cytologic diagnosis but was associated with blood contamination (more with a 22-Gauge needle) and cellular trauma and debris (more with a 25-Gauge needle).…”

“…In this study, we expected that two needle passes would yield cytologic material of sufficient quality. Multiple needle passes (2-10) have been used in LNs and other tissues without appreciably affecting the quality of cytologic material (Aulbach et al 2010, Arai et al 2019.…”

Assessment of the clinical usefulness of ultrasound‐guided cytological specimens obtained from gastrointestinal lesions in dogs and cats

“…A recent study that found the use of a 25 G needle is as effective as a 22 G in obtaining a diagnosis (Arai et al . 2019). However, the use of the 25 G needle was also associated with increased cell damage, and in a human study, an increased number of passes.…”

Effect of needle gauge on pain and specimen quality of ultrasound‐guided fine needle sampling without aspiration of the canine spleen

“…18 The characteristics of the needles used to sample the spleen are not always specified in the literature, but when they are, multiple diameters are mentioned, ranging from 21 to 25-gauge (G), with 22G needles being predominant, presumably selected by routine or general opinion rather than scientific agreement. 13,17,[19][20][21][22][23] Based on 20 years of FNA experience and close collaboration with the cytopathology department, our team no longer uses 22G needles, which we consider to be painful and traumatic and lead to hemodiluted cytologic specimens. For FNA of the spleen and other organs, we have successfully used 23 and 25G needles for 15 years and recently introduced the use of 27G needles based on current practice in human medicine for thyroid puncture.…”