ISSN 2398-2950      

Ureter: obstruction

ffelis

Introduction

  • Causess:
    • Intraluminal: urolithiasis (most common), solidified blood clots/pus, ureteritis.
    • Intramural: tumors (rare), strictures (fibrosis).
    • Extramural: abdominal tumors, ligation, uterine stump infections, trauma, ectopic ureterocele.
  • Signs: dysuria, hematuria, depression, vomiting, dehydration if renal failure present. Obstruction of a single ureter can also be clinically silent.
  • Treatment: identify and correct acid base/electrolyte abnormalities, establish diuresis. Remove obstruction (often surgical) or divert urinary flow (SUB device).
  • Stenting has been described which is minimally invasive, potentially avoids some surgical risks and can be successful.
  • Subcutaneous Ureteral Bypass surgery allows to divert the urine from the renal pelvis into the bladder, bypassing the blocked ureter and restoring kidney function. 
  • Prognosis: prolonged obstruction (>7 days)   →   permanent kidney damage. Renal damage increases with duration of obstruction.

Pathogenesis

Etiology

  • Intraluminal: urolithiasis Urolithiasis, solidified blood clots, inflammation and inflammatory debris (bacterial ureteritis, pyelonephritis Pyelonephritis).
  • Intramural: tumors of the ureter (not reported), strictures (secondary to ureteritis or ureterolithiasis), neoplasia or polyps at ureteral opening in the trigone.
  • Extramural:

Pathophysiology

  • Prolonged partial ureteral obstruction   →   dilation of proximal segment and hydronephrosis Hydronephrosis / hydroureter and fibrosis   →    reduction in renal blood flow and GFR Glomerular filtration rate   →    ultimately tubular dilation and interstitial fibrosis.
  • If complete ureteral obstruction is relieved within 7 days in experimental studiesin experimental studies   →   little permanent damage. Correction of complete obstruction at 4 weeks   →   renal function recovers to 30% of normal GFR.
  • Bilateral obstruction   →   azotemia Azotemia, uremia Uremia  →   eventual acute intrinsic renal failure Kidney: acute renal failure.

Timecourse

  • Correction within 7 days in experimental studies  →   little permanent damage.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Kulendra N J, Borgeat K, Syme H, Dirrig H, Halfacree Z (2021) Survival and complications in cats treated with subcutaneous ureteral bypass. JSAP 62(1), 4-11 PubMed.
  • Vrijsen E, Devriendt N, Mortier F, Stock E, Van Goethem B, de Rooster H (2020) Complications and survival after subcutaneous ureteral bypass device placement in 24 cats: a retrospective study (2016-2019). J Feline Med Surg ePub PubMed.
  • Chik C, Berent A C, Weisse C W, Ryder M (2019) Therapeutic use of tetrasodium ethylenediaminetetraacetic acid solution for treatment of subcutaneous ureteral bypass device mineralization in cats. J Vet Intern Med 33(5), 2124-2132 PubMed.
  • Fages J, Dunn M, Specchi S, Pey P (2018) Ultrasound evaluation of the renal pelvis in cats with ureteral obstruction treated with a subcutaneous ureteral bypass: a retrospective study of 27 cases (2010-2015). J Feline Med Surg 20(10), 875-883 PubMed.
  • Berent A C (2011) Ureteral obstructions in dogs and cats: a review of traditional and new interventional diagnostic and therapeutic options. J Vet Emer Crit Care 21 (2), 86-103 PubMed.
  • Zaid M S, Berent A C, Weisse C et al (2011) Feline ureteral strictures: 10 cases (2007–2009). J Vet Intern Med 25, 222-229 PubMed.  
  • Kyles A E, Hardie E M, Wooden B G et al (2005) Management and outcome of cats with ureteral calculi: 153 cases (1984-2002). JAVMA 226 (6), 937-944 PubMed.
  • Kyles A E, Hardie E M, Wooden B G et al (2005) Clinical, clinicopathologic, radiographic, and ultrasonographic abnormalities in cats with ureteral calculi: 163 cases (1984-2002). JAVMA 226 (6), 932-936 PubMed.
  • Nwadike B S, Wilson L P & Stone E A (2000) Use of bilateral temporary nephrostomy catheters for emergency treatment of bilateral ureter transection in a cat. JAVMA 217 (12), 1862-1865 PubMed.
  • Kyles A E, Stone E A, Gookin J et al (1998) Diagnosis and surgical management of obstructive ureteral calculi in cats - 11 cases (1993-1996). JAVMA 213 (8), 1150-1156 PubMed.
  • Lamb C R (1998) Ultrasonography of the ureters. Vet Clin North Am Small Anim Pract 28 (4), 823-848 PubMed.

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