Use of contrast-enhanced ultrasound for the diagnosis of idiopathic renal hematuria in a dog.

Background: Idiopathic renal hematuria (IRH) generally occurs in healthy large-breed dogs that are <2-years-old. It is characterized by recurrent bleeding from the kidneys of unidentified cause. The final diagnosis is reached through the exclusion of primary urinary system and systemic causes of hematuria along with the direct visualization by cystoscopy of hematic urine jets at the ureteral orifice.

Case Description: An 8-year-old female neutered Whippet was presented for investigation of a 4-week history of chronic intermittent macroscopic hematuria. Physical examination, systolic blood pressure, extensive laboratory workup (including coagulation profile and platelet count), urine culture, thoracic and abdominal radiographs, pneumocystogram, and double-contrast cystography were all unremarkable. B-mode ultrasound showed no abnormalities apart from a moderate amount of suspended echogenic amorphous material visible within the urinary bladder lumen. In the contrast-enhanced ultrasound (CEUS) study, a large amount of echogenic ill-defined material was noted projecting into the urinary bladder lumen from the right ureterovesical junction in the fundamental mode. This material was more conspicuous and markedly contrast-enhancing in the harmonic mode. Ultrasound contrast medium has the unique property to strictly remain within the vessels without interstitial trapping or elimination by the kidneys. Indeed, the presence of the micro-bubbles into the urinary tract lumen in the CEUS study was interpreted as a direct sign of active urinary tract bleeding. A diagnosis of IRH was reached through CEUS and B-mode ultrasound along with an extensive laboratory workup and periodic follow-up of the patient. No therapy was administered and at a 1-year follow-up, the patient was alive with no current episodes of macroscopic hematuria reported.

Conclusion: To the authors' knowledge, this is the first report describing the use of CEUS for the characterization of IRH. CEUS could represent a safe, non-invasive, affordable novel alternative technique to cystoscopy or cystotomy for the real-time diagnosis of IRH.