QUARTERLY BEAT
JULY 2026
bile with hepatic cells while also preventing seeding bacteria into the hepatic parenchyma while the later increases the chance the liver will serve as a pressure bandage to help prevent bile leakage should it occur. The transhepatic approach appears to be most recommended (Mattoon 2021) and is preferred by the author; however, it is not always possible in some small patients with a distended gallbladder and a small acoustic window. Care should be taken not to pass the needle through the pleural space, lung, or any surrounding vessels or gastrointestinal tract. After the procedure, the author obtains recheck imaging for peritoneal effusion immediately and 2-4 hours later, or sooner if the patient develops acute abdominal pain, vomiting, lethargy, or fever. In summary, if the diagnostic value of the procedure far outweighs the risk, it should be considered in some patients with appropriate client education and consent. The technique can also be used to therapeutically drain the gallbladder in cases of biliary obstruction until medical or surgical management resolves the underlying disease (Mattoon 2021). Lymph Nodes Limited evidence and the author’s experience suggests that the diagnostic yield of abdominal lymph nodes is lower than subcutaneous located ones (Amores-Fuster 2015 and Liffman 2017). Non-diagnostic sampling rates approach 30% (Amorex-Fuster 2015 and Liffman 2017). More specifically, one study (Feeney 2013) reported a cytologic non-diagnostic rate for mesenteric lymph nodes of 55% for peritoneal, mesenteric, and omental disease. The probability of a diagnostic sample increases with the number of submitted slides, so three is recommended as a minimum. For metastatic lymphadenopathy, diagnostic yield appears influenced by tumor type with the following sensitivities reported in one study (Fournier 2018): carcinoma = 100%, non-mast cell round cell tumors = 100%, mast cell tumors = 75%, sarcoma = 67%, and melanoma = 63%. In this study, the sensitivity (81%) and specificity (91%) as compared to histopathology was good, but these numbers are for lymph nodes located predominantly outside the abdomen. Mesentery, Omental, and Peritoneal Disease Cytology is useful in patients with focal or diffuse disease affecting the mesentery, omentum, and peritoneum. One study (Feeney 2013) demonstrated that cytology correctly classified the type of disease in 72% of cases. As mentioned above, lymph nodes were less likely than other samples/structures (e.g., fluid, mesentery, omentum, peritoneum, and masses) to yield a diagnosis. As expected, the presence of nodules/ masses or bowel/peritoneal thickening were more associated with neoplasia whereas localized or complex fluid collections were more associated with peritoneal disease. Urinary Tract Needle sampling of the kidney is predominantly used to diagnose neoplasia or infiltrative infectious disease (Liffman 2017). One retrospective study (McAloney 2018) of 96 cytologic samples in cats reported a diagnostic yield of 68%. Among confirmed cases, the
sensitivity and specificity for neoplasia (100%, 100%) was excellent but poor for non-neoplastic disease (16.7%, 100%). Aspiration techniques may be more diagnostic than non-aspiration techniques. The author tends to use both, collecting 1-2 of each for a total of 3-4 samples per kidney.
Ultrasound image of the left kidney. Photo courtesy of Dr. Amy Kaplan- Zattler, cVMA, DACVECC, MRCVS.
Cystocentesis is well established to be safe and effective for obtaining urine samples and hence not further discussed. The benefits and risks of FN-NA for diagnosing bladder neoplasia was discussed in Part 1.
Ultrasound image of the bladder. Photo courtesy of Dr. Amy Kaplan-Zattler, cVMA, DACVECC, MRCVS.
Sampling of the prostate and associated paraprostatic cysts/abscesses is safe with a low risk for septic peritonitis (Thrall 1985, Raskin 2015, Bussadori 1999, Boland 2003). Needle techniques with
or without alcohol embolization are also reported as a nonsurgical alternative for the treatment and resolution of prostatic
abscesses and cysts in the dog. Incidental prostatic cysts without
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