Ch 115 ureters Flashcards
What % of felines have circumcaval ureters?
Right 30.6%
Left 1.3%
Bilateral 3.3%
7% have a double cava
List the layers or the ureter
Outer adventitial layer
Central muscular layer
Inner mucosal layer (lamina propria and transitional epithelium)
- approximately 0.4 mm diameter in cats
- 2.0 to 2.5 mm in dogs
- vesicular attachment, they recurve slightly, resulting in a “J shape”
paired fibromuscular tubes that transport urine via peristaltic activity
blood supply
- ureteral artery, arising from the caudal aspect of the renal artery
- anastomoses with the ureteric branch of the caudal vesicular artery, which in turn arises ultimately from either the prostatic or vaginal artery
Ureteral Obstruction
Pathophysiology
- Potential for progressive renal dysfunction (changes continue after relief)
- Spontaneous passage of a ureteral stone is reported [Weiss 1977]
- Kidney is a highly specialized, complex organ and can restore its functionality after some degree of damage
- Nature of obstruction: partial and complete, unilateral vs bilateral etc
- complete > cystic atrophy abd fibrosis expected
- The longer the duration of ureteral obstruction, the less likely that the kidney will recover to where the animal is no longer azotemic
- experimental studies on healthy > no definitive prognostications can be made regarding dogs or cats with bilateral renal disease
- big kidney little kidney
classified into
- intraluminal, intramural and extraluminal
- acute or chronic, static or dynamic
- unilateral or bilateral, partial or complete
What is the response in terms of ureteral pressure in response to acute ligation?
Ureteral pressures increase and peak by 5 hours and then lessen but remain elevated for 12-24hr
What is the response of renal blood flow after acute ureteral ligation?
24hr - 40% of normal
2 weeks - 20% of normal
Results in a decreased GFR and a compensatory increased GFR in the contralateral kidney
What cellular response is seen in response to acute ureteral ligation?
- Influx of macrophages and T-lymphocytes
- Macrocyte proteolytic enzymes and cytokines resilt in fibroblast recruitment and activation
- Interstitial fibrosis or glomerulosclerosis
What is the expected return of GFR after ureteral obstruction in previouslt healthy kidneys?
- 1 week obstruction - 65% of normal GFR over 5wk
- 2 week obstruction - 46% of normal over 4m
Slight, moderate and severe fibrosis occurs over 1, 2 and 3 weeks respectively
List important points to discuss with the owner in a cat with ureteral obstruction (4)
- Cannot predict how long the obstruction has been presetn and how well the cat will recover
- Most have some degree of chronic interstitial nephritis which will progress despite surgery
- If azotaemic with unilateral obstruction, cat has bilateral kidney disease
- Significant risk of complications - overall mortality 18-21%
ureteral obstructions in cats
- Predisposition (0.4-0.8mm diameter), calcium oxolate, strictures up to 25%, circumcaval ureters
- Concurrent renal insufficiency/CKD in 56 -94%
- 80–90% of ureteral obstructions in cats are considered partial based on antegrade pyelography
- Close to 50% of the cats are expected to sustain chronic kidney disease
- 40% have ureteral stone recurrence
medical mgmt
- diurese the patient for some amount of time (1 to 4 days) before surgery
- induce ureteral relaxation (e.g., calcium channel blockers, glucagon, amitriptyline)
- weighed against the risks for increased renal damage secondary to prolonged obstruction
- only 7/52 had a significant improvement in creatinine concentration with medical management alone
- One- and 2-year survival statistics were 66% and 66%, respectively, compared with 91% and 88% for those treated surgically
pre-op
- Localization of a ureteral obstruction is most commonly performed using abdominal ultrasonography
- many calcium oxalate ureteral calculi (the most common mineral type in cats) can be seen on plain radiographs> wont see stircture or blood lith
- determine the degree of ureteral and renal pelvic dilatation
- Hydroureter and hydronephrosis common, however pelvic dilation is not always present [Lemieux 2021]
Pelvis may dilate due to pyelonephrosis or IVFT
List options for surgical management of ureteral obstruction
Ureteral resection with reimplantation
Ureterotomy
Double-pigtail ureteral stent
SUB
Ureteral resection and anastomosis
Lithotripsy
Ureteral Stent Placement
- retrograde stent placement can be performed via cystoscope in female cats (nonsurgical), this is less successful (4 of 21 [19%] )
- surgical placement: A guidewire is placed, either retrograde from the ureteral orifice to the renal pelvis or normograde (preferred) through the greater curvature of the kidney, down the ureter, past the ureterolith, and into the bladder.
- placement of a double-pigtail indwelling catheter
- ureterolith(s) are not typically removed, but can be, via a ureterotomy
- reobsturction due to stricture is a more significant concerns for stents
- Stents allow passive ureteral dilation over several days to weeks, resulting in improved urine flow and aid in spontaneous stone passage.
> why the removal of ureteroliths is not recommended or required during stenting. - dilation aids in faster stent exchange if required and often with a larger diameter stent.
What % of cats need removal or replacement of a double pigtail stent?
27% - stent occlusion or dysuria
Complications
- stranguria/dysuria, due to irritation of the trigone
- ureteral trauma during stent placement
- urinary tract infection
- migration
- occlusion/stricture
- mortality (6-15%)
- stent removal or replacement was required in 19 of 70 (27%) cats because of long-term complications, including stent occlusion and dysuria. (Berent 2014)
Comparison between stent vs ureterotomy in 62 cats:
- When comparing the ureteral stenting and ureterotomy groups (historical control), there was no significant difference in the time to postoperative improvement in azotemia, there was no significant difference between groups with regard to hospitalization time or likelihood of developing uroabdomen
- Culp 2016:
SUB
- locking-loop nephrostomy and cystostomy catheters connected under the skin via a specialized port
- nephrostomy catheter is placed under fluoroscopic guidance using a modified Seldinger technique
- no fluoro guidance study (Livet 2017, 19 cats, 1 intra-op comp)
ultrasound guided study (Butty 2021) - catheters to maintain a gently curving transabdominal course in an effort to prevent kinking
- Flushing with sterile saline every 3 to 6 months is recommended to ensure patency and reduce encrustation.
List complications associated with a SUB
reobstruction 4-32%
Occlusion with blood clot under 3%
Kinking 3%
Urine leakage - rare
Infection 26%
Migration into intestines
stent exchange 17%
Mortality 5-19%
partial blockage
- tetra-EDTA (T-FloLoc™; Norfolk Vet Products), which is an antibacterial solution that prevents biofilm production and is also an anticoagulant
- partial blockage > flushing with T-FloLoc, however, if the catheter is completely blocked then it is unlikely that the solution will be able to clear the obstruction.
- A blocked catheter is only replaced if the ureter is obstructed (as observed on an antegrade pyelogram) or if there is evidence of ongoing and clinically significant UTI.
- Duval 2022:
SUB outcome
- 98-100% surgical success
MST 762-923 days (Berent 2018, Wuillemin 2022) - Perioperative Fluid overload is significantly associated with outcome, so judicious fluid therapy is recommended
- Positive outcomes > low IRIS CKD classification and Crea/Urea levels in the first 24hrs post sx
- Tailor clients expectations in regards to stone recurrence or reobstruction > life long maintenance in required
- approximately 10% in-hospital mortality and 48% complication rate. Most complications were manageable, MST > 2 years (Kulendra 2021)
retrospective study comparing SUBs and stents
results supported the superiority of SUBs due to:
- shorter duration of surgery
* fewer complications
* fewer additional procedures after device placement
* and longer survival time.
SUBs vs STENTS
- case selection > cats with suspect strictures or circumcaval ureters are recommended to not be stented
- Reobstruction rates can be similar, main difference is how they are managed and while stent exchange may be simple, it is still more invasive than flushing. If the requirement of exchange can be reduced with the TFLOLOC protocol, then SUBs will likely be the statistically superior device.
- both techniques offer long, good quality lives
- Uutcome is largely determined by the progression and severity of the underlying CKD after the decompressive surgery.
- Cats with advanced CKD have a more guarded prognosis
- SUBs can be performed quicker, with less post op morbidity and have reduced requirement for exchange.
- still need more, higher quality studies
ureterotomy
- There has been a move away from more traditional surgery due to high reported complication rate of urinary leakage, recurrent stricture and mortality of approx 20%.
- More recent evidence appears to support interventional procedures of stents and SUBS that bypass the obstruction and allow acute decompression
- Urine leakage (12%)
- In dogs, ureterotomies that are left open will heal within 12 days if urine is evacuated from the abdomen
- fibrosis and partial ureteral obstruction were shown to be more common in pigs if the ureter was allowed to heal by second intention
Post obstructive diuresis
- defined as polyuria after relief of a urinary tract obstruction
- clinically important because it can lead to dehydration and profound electrolyte and water disturbances if not managed appropriately
- urine output >2 mL/kg/h
- 2 studies: 71-88% cats develop POD
- Results of the present study indicated that high BUN, creatinine, phosphorus, and potassium concentrations 24 hours before decompressive surgery in cats with ureteral obstruction were associated with longer and more severe POD following surgery.
- Balsa 2019:
Alternative surgery options
ureterotomy,
ureteral reimplantation,
ureteronephrectomy,
and at times renal transplantation
- Kyles et al reported 2 retrospective studies involving over 150 cats.
- complications (over 30%) and the mortality rates ranged from 18% to over 30%, depending on the type of procedure performed
- These studies not only included cats that had a ureterotomy or ureteral reimplantation, but also those that had renal transplantation or ureteronephrectomy procedures
- Over 10% of cats that survived the these surgical complications required a second surgical procedure (30% subsequently euthanized or died for serial complications.)
- small number had long-term imaging follow-up, and 40% of those that were followed had evidence of a recurrence of a ureteral obstruction
Lorange 2020: Postoperative outcomes of 12 cats with ureteral obstruction treated with ureteroneocystostomy, Vet Surg
- ureteroneocystostomy with (6/12) or without (6/12 – 4 temporary) double pigtail catheter
- survival: 11/12 survival to discharge
- creatinine: decreased in all cases – not influenced by double pigtail catheter placement
- complications: 2/12 without double pigtail → revision for uroabdomen
- long-term complications more common with double pigtail (hematuria, pollkiuria,
UTI)
What are the most common ureteroliths in dogs?
Struvite and calcium oxalate
Approx 50% with ureteroliths had concomitant nephroliths or cystoliths
treatment of canine ureteroliths
- ureterotomy or neoureterocystostomy are easily performed
- double-pigtail ureteral stents (fluro guided)
Lithotripsy
- extracorporeal shockwave
- In one study, successful treatment was reported in 6 of 7 dogs with ureteroliths, although 4 of 7 dogs required more than one retreatment.
- All dogs had concurrent nephrolithiasis.
dog stent outcome
- Ureteral stent placement was performed endoscopically, surgically, or both, with fluoroscopic guidance.
- follow up > 1,555 days, with 30 of 44 dogs alive at the time of last follow-up
- post of infection 25%
- Pavia 2018: Outcome of ureteral stent placement for treatment of benign ureteral obstruction in dogs: 44 cases (2010–2013) JAVMA
dog SUB outcome
- no perioperative or procedure-related deaths
- good short term results
- long-term complication> mineralisation of six devices, four required exchange
- MST >774days
- Milligan 2020: Outcome of SUB placement for the treatment of benign ureteral obstruction in dogs: nine dogs and 12 renal units (2013 to 2017) JSAP
What is the most common primary ureteral neoplasia in dogs?
Benign fibroepithelial polyps
DDx: leimyoma, TCC, sarcoma, MCT
neoplasia
- Secondary involvement of a ureter by tumors of the urinary bladder or a kidney is more commonly reported.
- Ureteronephrectomy is usually performed when primary ureteral tumors do occur
Where are congenital ureteral strictures most commonly located?
Ureteropelvic junction
bilateral hydronephrosis and renal failure
What is a urinoma?
What is the treatment?
Uroretroperitoneum may result in the formation of a urinoma
A collection of urine within the retroperitoneal space that causes fat necrosis and subsequent reactive fibrosis
Tx: ureteronephrectomy with ablation or omentalisation of the urinoma cavity
Ureteral Trauma
Ureteral Injury Associated With Ovariohysterectomy
- inadvertent ligation, transection, or resection or from obstruction secondary to ovarian, uterine, or vaginal granuloma formation.
- Clinical signs associated with uremia (e.g., vomiting, lethargy)
- signs are not immediately apparent (e.g., hydronephrosis) if there is unilateral obstruction
blunt trauma
- uroperitoneum
- luid creatinine and potassium concentrations
- Excretory urography or ct pyelography
Tx
- - ureteral reimplantation for mid to distal ureteral avulsions
- ureteronephrectomy or ureteral ligation with SUB placement for proximal avulsions.
Surgical Techniques
- ureterolithiasis, repeat ultrasonography is recommended immediately before surgery to confirm the location of all stones because calculi can migrate in either direction.42,92
- Intraoperative ultrasonography is sometimes required to confirm stone location or to confirm that all stones have been removed.
- Ureterotomy or neoureterocystostomy in small dogs and cats requires magnification of the surgical site
- Microvascular instruments and suture (7-0 to 10-0) are also required.
Ureterotomy
- urinary bladder is drained
- Larger ureteroliths (>2 to 3 mm) can often be visualized or palpated within the ureter.
- Approximately 75% of cats have unilateral obstruction
- left feline ureter often has a bend approx 3 cm distal to the kidney > common location for obstruction by ureteroliths.
- Visibility is improved cellulose surgical spears, Suction avoided to reduce ureteral edema
- temporary stent during suturing > This prevents incorporation of the back wall and subsequent stricture.
- ## Interrupted or continuous microvascular sutures (7-0 to 10-0 for cats, usually nylon)
Ureteral Reimplantation (End-to-Side Neoureterocystostomy
- renal transplantation > the intravesical technique eliminated the formation of obstructive granulomas seen with the older technique
- experimental dogs > renal technetium transit time increased for 2 to 4 days after intravesical reimplantation, returned to normal over 4 to 11 days after surgery in most cases
What are the 2 options for end-to-side neoureterocystostomy?
- Intravesicular - vental cystotomy performed to pull ureter from outside in and suture mucosa to mucosa after spatulating the ureter
- Extravesicular - no cystotomy required, sutured to mucose with knows external
Cats with contralateral nephrectomy had creatinine concentrations reduce more rapidly with extravesicular technique
List options for tension reduction for a neoureterocystostomy
- Renal descensus (shifting the kidney caudally)
- Pexy apex of bladder to caudal pole of kidney
- Pexy apex of bladder to iliopsoas muscle (psos cystopexy)
- modified boari flap (Aronson 2018)
- pelvicocystostomy using tube cystoplasty in a cat
What is the prognosis for reimplantation vs ureterotomy
- Similar rates of uroabdomen (15% reimplantation vs 16% ureterotomy)
- Persistent obstruction more common after reimplantation (11% vs 3%)
Neoureterocystostomy (Side-to-Side)
- For intramural ureteral ectopia, a ventral cystotomy is performed
- the ureteral and bladder mucosa are sutured together with 5-0 to 9-0 monofilament absorbable interrupted sutures
- distal ureteral segment is then ligated
Ureteral Resection-Anastomosis
- disparity in ureteral luminal diameter between the dilated proximal and normal distal ureter, distal ureter is spatulated so that it matches the diameter of the proximal ureter
- 3 to 4 weeks for coordinated peristalsis to return across the anastomosed ureter.32
- ureteral catheter is left in place.
- fibrous tissue/stricture and leakage main cocnerns
What is a ureterocoele?
What are the subtypes?
Treatment?
Dilatation assoc with the distal ureter or ureteral orifice that occurs due to faulty embryonic development (Chwalla membrane fails to regress)
- Orthotopic/intravesicular - Ureteral orifice in normal positionand entire ureterocoele is within the bladder
- Ectopic - If any portion of ureterocoele is within the bladder neck or urethra
- concurrent ectopic ureter > urinary incontinence
Treatment: Resection of the ureterocoele (ureterocoelectomy) +/- neoureterocystostomy (if ectopic)
- Endoscopic laser-ablation for the treatment of orthotopic and ectopic ureteroceles
- poorer outcome if associated with ectopia
What breeds and sex are overrepresented for ectopic ureters?
Skye terriers
Golden retrievers
Labs
Huskies
Newfies
Bulldogs
WHWT
Fox terriers
min and toy Poodles
Females are 20x more likely
Ureteral Ectopia
- In dogs > majority are intramural; they enter the bladder wall in the normal anatomic location and continue to travel submucosally
- In cats, uncommon in dogs, ureters may run completely separate from the bladder and urethra (extramural) until they empty into the distal urogenital system.
- often associated with other urogenital abnormalities, including:
> hydroureter
> small, misshapen, or absent kidneys
> vestibulovaginal abnormalities such as paramesonephric remnants.
Embryology - normal
- During urogenital development, the pronephros, mesonephros, and metanephros appear sequentially, with remnants of each possibly retained in the embryo.
- In mammals, the pronephric duct persists as the mesonephric duct, which becomes vestigial in females but forms the deferent duct in males.
- The ureter originates from the metanephric duct, a bud of the distal mesonephric duct.
- Initially, both ducts share a common opening into the bladder, but as the bladder grows, they separate.
- The mesonephric ducts shift caudally, opening on the dorsal urethral wall, while the ureters maintain their connection to the bladder.
Embryology - ectopic
- If the metanephric duct originates more cranially than normal on the mesonephric duct, the metanephric duct will not reach and establish an individual opening into the bladder
- The metanephric duct will then be carried caudally with the mesonephric duct to open in the bladder neck or urethra of females or the deferent duct or urethra of males.
- Most cases appear to terminate in the urethra of females and males
daignosis
- Continuous or intermittent incontinence when the animal is young
- most animals produce a urine stream during conscious micturition
- UTI reported in up to 83% of bitches presenting with EU, most E. coli
RADS
- traditionally relied on excretory urography±retrograde contrast studies
- - significant discordance between radiographic and surgical findings, with only 78∙2% EUs being correctly identified
- enema to empty the colon and fluoroscopy improves accuracy
- Pneumocystography in conjunction with excretory urography may improve
CT
- remove superimposition of tissues
- - Contrast dosage and acquisition times have also been defined
- - CT has repeatedly been shown to have a high degree of accuracy + non invasive
ultrasound
- - determine if an ectopic ureter is present within the bladder neck or proximal urethra
- evaluate the urinary bladder for the presence of ureteral “jets”
- use ultrasound as an initial screening modality but this is a highly operator dependent
cystoscopy
- evaluation of the vagina, urethra, and urinary bladder
- determining the exact location of ectopic orifices
- 100% correlation between cystoscopic and surgical findings
- can be surgically treated at the same time
- disadvantage is the inability to examine the upper urinary tract
sens and spec of fluroscopy to Dx ectopia?
- 80% sensitivity and 100% specificity
enema to empty the colon and fluoroscopy improves accuracy
sens and spec of CT to Dx ectopia?
4D-CTEU
- sensitivity 91-100% + specificity 100%
4D-CTEU showed a sensitivity and specificity of 97% and 94.6%, respectively
sens and spec of ultrasound to Dx ectopia?
sensitivity 87.8% and specificity 86.7%.
List the treatment options for ectopic ureters
Neoureterocystostomy (extramural)
- End-to-side intravesicular or extravesicular
- Side-to-side
Cystoscopic guided laser ablation (intramural)
Extraluminal
- Open surgery is only treatment option for extramural > ligation of the distal ureter and re-implantation
- An adaptation in technique (three-stitch ureteroneocystostomy) based on evidence from the human literature, and compares favourably to previous techniques
- higher complication rate reported:
complications
- hydroureter/hydronephrosis secondary to mucosal oedema, surgical trauma or stricture formation
open surgery
- Persistence of urinary incontinence has been reported to occur in 42 to 71% of dogs after surgical interventions, including neoureterostomy, ureteral re-implantation and ureteronephrectomy
- good to excellent outcome in 92.5% of dogs 1 month postop and in 81% of dogs at long-term outcome
recurrence of incontinence was observed in 35%, most of these responding to adjuvant medical treatment - Major complications (11%) and included uroabdomen (3)
- Comparison of open surgery to CLA
- Minor lower urinary tract complcations were more frequent after neoureterostomy (100%) compared to CLA (13%)
- 1 major complication, only in neoureterostomy group
Incontinence did not recur in any dog treated with CLA - Recurrence incontinence in 42% (5/12) of dogs treated with neoureterostomy;
- The median duration of follow-up time was 38.9 months
- 22/25 (88%) dogs achieved continence after correction of EU ± additional medical/surgical treatment
Dekerle 2022
Cystoscopic Laser Treatment
- only applicable for intramural EU
- shown to be safe, with minimal risk of complications
- no significant complications were encountered in the treatment of 46 dogs (Smith et al. 2010, Berent et al. 2012).
- This compares very favourably with reported major complication rates for surgical procedures of 4 to 11%
- Evaluation of the efficacy restricted to comparison with historical surgical controls, due to the lack of any prospective comparative studies
- In study with longer follow-up (median 2.7 years), 14 of 30 female dogs had regained and maintained continence without the need for additional therapy
- Overall, 67.7% continent after CLA with or without adjunctive medical management.
17 dogs (54%) remained incontinent after CLA
- Overall, 67.7% continent after CLA with or without adjunctive medical management.
- Complete urinary continence achieved in 20/32 dogs (63%) with CLA alone. With addition of medical/surgical intervention > 72%
Postprocedural neutering did not affect the continence score.
risks of scarring and proliferative reaction that resulted in stranguria.
Hoey 2021
complications of CLA
- perforation,
- haemorrhage
- recanalization
Cystoscopic-guided scissor transection
- More accessible alternative to laser
- 3/7 dogs were completely continent with CST-EU alone, 3 others became continent or were markedly improved with the addition of medications
Jacobson 2022:
Complications were minor, and only 3 dogs showed transient lower urinary tract sign
Ureteral Ectopia in Male Dogs
- Male dogs make up fewer than 15% of reported cases
- success rate after surgical correction may be higher than females > This may be due to the longer urethral length in male dogs
- In 5 case reports, all 5 were continent after ligation of the distal ureteral segment and neoureterocystostomy., or increased pressure within the prostatic urethra. Two of the dogs also had a ureterocele resected
- 82% continence rate in a review of 16 male dogs treated with conventional surgery. Anders 2012
- 100% continence in 4 male dogs treated with cystoscopic-guided laser ablation (bilateral in 75%)
Outcome of Surgery
- minimally invasive treatment option has significantly reduced the morbidity and mortality
- yet to improve and the long-term success continues to be in the region of 50 to 70% in females
- continued incontinence likely have functional abnormalities of the bladder neck and urethra
- for long-term outcome are broadly similar, suggesting that one technique is not superior to another
- another 7% to 28% of dogs becoming continent with a combination of surgery and treatment with drugs such as phenylpropanolamine that increase urethral tone.
- Recommend repeat cystoscopy – laser ablated, may result in ureteral openings that are not optimally positioned
- The importance of concurrent anomalies, their contribution to outcome, and whether they should be treated concurrently with ectopic ureters is unclear.
- Preoperative urethral pressure profiling reported to be a potential useful tool in predicting postoperative incontinence (not been validated in a larger group of dogs
Ureteral Ectopia in Cats
- Uncommon
- In a review of 23 cases
no breed or gender predilection
21 of 23 cats were incontinent
13 cats unilateral
28 of 31 were extramural (unlike in dogs) - incontinent cats should be evaluated for ascending urinary tract infection.
- most common correction is ureteral reimplantation, as long as hydronephrosis is not too severe.
- The response to surgery may be better in cats than dogs; postoperative resolution of clinical signs was reported in 16 of 18 cats
What is the major difference regarding ectopic ureters in cats vs dogs
Majority of cats are extramural
Presentation, diagnosis, and outcomes of cats undergoing
surgical treatment of ectopic ureters
Gabriela L. Cortez 2024
berent
Retrospective, multi-institutional study.
Animals: Twelve client-owned cats.
Presurgical
diagnostic imaging diagnosed ectopic ureters by abdominal ultrasound
(8/10), contrast enhanced computed tomography (3/3), fluoroscopic
urography (3/4), or cystoscopy (6/7).
Eight of 12 cats had extramura
Eight > ureteroneocystostomy,
one cat underwent neoureterostomy,
two cats underwent cystoscopic laser ablation, and one cat underwent nephroureterostomy. Immediate postoperative complications
three cats; one cat required additional surgical intervention.
Short-term complications occurred in three cats, and long-term complications in two cats (16%)
All cats had improvement of their urinary incontinence scores, with complete
resolution in 11 cats (91%)
The sample size was too small to make any
meaningful comparisons between outcomes; however,
major complications were uncommon regardless of
technique.
Receiver operating characteristics of computed tomography
(CT) compared to cystoscopy in diagnosis of canine ectopic
ureters: Thirty-five cases
Min Kyong Song 2024
Study design: Retrospective cohort study.
Animals: Thirty-five client-owned dogs
The ability of CT to identify a normal and intra-or extramural ectopic
ureters conclusively and correctly was 13/26 (50%) and 32/41(78%), respectively.
CT did not accurately predict anatomy of ureters; CT findings
may need confirmation by cystoscopy and possibly intraoperative fluoroscopy
prior to determining if CLA is indicated or not.
Modified endoluminal ureteral
stenting for the management of
proximal ureteral obstruction in two
cats
Teng-Xiang Khoo 2023
– modified endoluminal stents for proximal ureteral obstruction
- avoidance of irritation of UVJ and alterations to ureteral peristalsis, vesicorenal reflux
the physical
effect of intra-ureteral stent termination on the ureter
at the stent end, is unknown. Intra-ureteral stent
termination also precludes minimally invasive cystoscopic
or fluoroscopic-guided removal,
Benign ureteral obstruction in cats: Outcome with medical
management
Isabelle Merindol 2023
JIVM
Animals: Seventy-two client-owned cats with 103 obstructed kidneys. received >72 hours of MM
considered a success in 30% (31/103), partial success in 13% (13/103), and failure
in 57% (59/103) of kidneys. Success was reported in 23% (17/75) of kidneys with
uroliths, 50% (7/14) with pyonephrosis, and 50% (7/14) with strictures
Distal and smaller uroliths
(median length, 1.85 mm) were significantly associated with success (
Median survival times were 1188 days (range, 60-1700 days),
518 days (range, 7-1812 days), and 234 days (range, 4-3494 days) for success, partial
success, and failure, respectivel
- positive urine culture rates of 25% to 30% in cats
with CKD may not represent a complication of SUB placement mentioned by the authors, because similar rates are reported after
surgery without an implant and in cats with CKD
- positive urine culture rates of 25% to 30% in cats
- given the current veterinary literature
available, identification of individual patients with BUO (with different
causes and sites of obstruction) that would most benefit from medical
management, surgery (eg, ureterotomy, ureteroneocystostomy) or
SUB placement is not clear and merits further investigation.
Feline ureteral rupture with para-ureteral urinomas following blunt trauma:
clinical presentation and long-term outcome after treatment by urinary
diversion for five cases from 2012 to 2019
NZVJ
Four cats received subcutaneous ureteral bypass (SUB) device placement and one
had ureteral anastomosis over a stent
Extravesicular, two-layer, side-to-side ureteroneocystostomy
combined with tension-relieving techniques for feline
proximal ureteral obstruction: A retrospective study
Kazuhisa Oyamada 2023
Ten privately-owned cats with ureteral obstruction near the ureteropelvic
junction (UPJ).
(renal descensus, ureterocystopexy, and nephrocystopexy).
Perioperative complications included ureteral
catheter dislodgement (3), transient pollakiuria (2), and dysuria (1), but no specific
treatments were requir
Seven of the 10 cats were alive without recurrent ureteral
obstruction at the end of this retrospective study.
Another possible advantage of ETSUTT was that the
wider anastomosis and remaining very short ureter may
have allowed spontaneous passage of small nephroliths
into the bladder
This procedure may be especially suitable for obstructions
caused by ureteral stricture or occlusion of a SUB device.
Evaluation of two nephrocystostomy techniques for
ureteral bypass in cats
Robert J. Hardie 2023
Study design: Experimental study.
Animals: Twelve, adult, purpose-bred, cats.
A simple NCT (n = 3) or bladder cuff NCT (n = 9) was performed
in the right or left kidneys.
All simple NCTs became obstructed after catheter removal. All bladder
cuff NCTs were patent, and CT revealed contrast flow into the bladder
Complete ureteral bypass was possible in cats using
only native tissues.
Transmural migration of a
subcutaneous ureteral bypass into
the intestine in three cats
J. Boullenger 2022
cross-sectional imaging modali
ties
such as CT scan could allow the migration to be identified
The triggering mecha
nism
of the transmural migration may have been a primary
foreign body reaction from the SUB™
Another possibility is that the migra
tion
was initiated by an infection leading to adhesions and then
a secondary foreign body reaction
the cyanoacrylate glue used to secure the cuff could
have encouraged the development of adhesions
As it was associated
with UTI, acute onset of gastrointestinal signs and tube obstruc
tion,
any of these elements should raise suspicion of this recently
described complication
Direct renal pelvicocystostomy using
tube cystoplasty in a cat with ureteral
obstruction
K. Hoshi 2022
ureteral
stent and subcutaneous urinary bypass failed after their placement due to rapid mineralisation of the lumen.
of bacterial cystitis could easily progress
to pyelonephritis.
route of urine passage without use of artificial
material and therefore does not include the risk of mineralisation
on foreign body surfaces and does not add a nidus for infection.
Second, this technique provides a large-diameter and flexible tubelike
structure for the calculi to pass through, as opposed to the
small-diameter a
Cystoscopic-guided scissor transection of intramural
ectopic ureters as a novel alternate minimally invasive
treatment option to laser ablation in female dogs:
8 cases (2011–2020)
Else Jacobson 2022
8 incontinent female dogs with intramural ectopic ureters
median procedure time: sx 105min (40-170), GA 118min (65-320)
- 6/8 immediate improvement in continence; 3/7 (42.9%) long-term complete continence
- additional 3/7 (42.9%) continent or improved with medication for USMI
- complications: 3/7 transient LUT signs
Evaluation of preoperative
ultrasonographic parameters to
predict renal recovery in long-term
survivors after treatment of feline
ureteral obstructions: 2012–2019
Elisa P McEntee1 2022
No preoperative imaging characteristics or biochemical findings were found to be significantly associated
with long-term serum creatinine concentrations
Lemieux 2021 – feline ureteral obstruction may be associated with minimal renal pelvis dilation
26% kidneys had renal pelvis mesurement <4mm; 74% >4mm
- 8% <2mm
- median renal pelvis diameter 6.6mm (1.1-37.0); ureteral diameter 3.2mm (0.0-11.0)
- pathology: 70% secondary to stones, 21% positive culture
- absence of dilatation does not rule out ureteral obstruction
Feline ureteral obstruction:
a case-control study of risk
factors (2016–2019)
Kennedy 2022
age, sex, breed, housing, total calcium not associated
- dry food → 15.9x more likely to develop ureteral obstruction
Outcomes of 25 female dogs treated for ectopic ureters by
open surgery or cystoscopic-guided laser ablation
Dekerle 2022
surgery: 17/25; CLA 8/25
- complications: 18/25 (72%) minor, 2/25 (8%) major
- continence: 1-month post-oop continence in 20/25 (80%)
- recurrence in 5/25 at median 24.9m with resposne to medical management
- overall continence maintained median 66m in 22/25 (88%) with treatment
- CLA → fewer complications and recurrence of incontinence
- case numbers small and not equal
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)
Julien Fages 2018
peritoneal/retro-peritoneal effusion rare: 4/25 short-term, 1/14 long-term
- decreased renal pelvis width: short-term 2.4mm (0-7.0); long-term 1.7mm (0-3.5)
- pre-op 11.7 (0.9-41)
- all cats without complication → pelvic width ≤3.5mm at 3-months
- complications: 16/27 (59.2%) overall – 9/27 (33%) non-obstructive
8/27 (29.6%) obstructive
- renal pelvis size post-op often close to normal renal pelvis size
Factors associated with positive
urine cultures in cats with
subcutaneous ureteral bypass
system implantation
Catrina E Pennington 2021
In total, 10 cats (8.5%) had a positive postoperative culture within 1 month postsurgery and 28 cats
(23.7%) within 1 year postsurgery
Perioperative hypothermia and preoperative positive culture were independent
predictors of a postoperative positive culture and this should be taken into consideration when managing these
cases. Positive postoperative culture rates were higher than have previously been reported.
Complications and survival after
subcutaneous ureteral bypass
device placement in 24 cats:
a retrospective study (2016–2019)
Emily Vrijsen 2021
fair prognosis!
complications: 19/24 (79.2%) overall
- intra-op: 4/24 (16.7%) - ischemic encephalopathy, flluid overload, hyperkalemia
- peri-op: 10/23 (43.5%) - device obstruction, UTI
- post-op: short-term 9/18 (50%)
long-term 14/16 (87.5%) - obstruction, UTI, sterile cystitis, pyelonephritis
- risk factors: older cats → peri-op complications; increased Hct → short-term
- survival: 19/24 (79.2%) survival to discharge – older cats less likely to survive
complication rate was higher and the MST shorter than previously reported in cats undergoing SUB placement.
Despite good short-term survival, the development of complications may necessitate regular and intensive control
visits. Owners that consider SUB placement should be informed that follow-up can be strenuous and expensive
Long-term outcome of female dogs treated for intramural
ectopic ureters with cystoscopic-guided laser ablation
Hoey 2021
and determine the effect of post-CLA neutering on urinary continence.
Study Design: Retrospective clinical study.
Animals or Sample Population: Thirty-four
complications: urethral tear in 2/34 – managed conservatively
- complete or near-complete continence in 26/32 with 3 dogs requiring additional tx (81%)
- post-CLA neutering did not affect continence scores
Survival and complications in cats
treated with subcutaneous ureteral
bypass
N. J. Kulendra 2021
95 cats with 130 SUB
- survival: 85/95 (89.5%) survival to discharge; MST 530d (7-1915) overall
- survival associated with pre-op creatinine:
- creat ≥440μmol/L (IRIS 4-5) → MST 530d
- creat <440μmol/L (IRIS 1-3) → MST 949d
- complications: minor 18/95 (19%), major 46/95 (48%)
- UTI: 27/85 (31.7%)
10% in-hospital mortality and a high complication rate. Most complications were manageable, resulting in an overall median survival time of over 2 years
If it was difficult to differentiate ureteral obstruction from pyelonephritis
on ultrasound, an antegrade pyelogram was performed preoperatively
as this technique was proven to be 100% sensitive
and specific in detecting obstructions (Adin et al. 2003).
Two cats in this study had obstruction of the nephrostomy
catheter by blood clots. At the original surgery, there was profuse
haemorrhage after placement of the initial catheter
The use of tissue plasminogen activator
(TPA) infusion into the SUB prior to replacing the nephrostomy
catheter has been described (Norfolk Vet Products n.d.);
SUB was removed after 6 weeks of unsuccessful
antibiotic therapy following demonstration of patency of both ureters.
Postoperative outcomes of 12 cats with ureteral obstruction
treated with ureteroneocystostomy
Maxime Lorange 2020
ureteroneocystostomy with (6/12) or without (6/12 – 4 temporary) double pigtail catheter
- survival: 11/12 survival to discharge
- creatinine: decreased in all cases – not influenced by double pigtail catheter placement
- complications: 2/12 without double pigtail → revision for uroabdomen
- long-term complications more common with double pigtail (hematuria, pollkiuria,
UTI) - Seven cats were alive a median of 329 days (range, 8-1772) after surgery
- During the follow-up period, none of the cats in this study were reported to have recurrent ureteral obstruction.
- nephroliths were identified in seven cats at the
time of surgery, but none were diagnosed with recurrence - The temporary ureteral catheter (instead of stent) must be small enough (ie, 3–5-Fr infant feeding
tube) to allow introduction in the ureter without obstruction
of the urethra, allowing urination around the catheter
Reobstruction rates requiring revision surgery for
SUB, 5% to 17%
stents, 8% to 32%
ureteral surgeries 11% to 31%
presence of nephroliths did not influence the rate of postoperative reobstruction.
Outcome of SUB placement for
the treatment of benign ureteral
obstruction in dogs: nine dogs and
12 renal units (2013 to 2017)
M. L. Milligan 2020
11/12 ureters previously stented → SUB for recurrent stricture, ureteritis, stent migration
- no short-term worsening azotemia
- complications: mineralisation of 6/9 → 4/6 exchanged
UTI 5/9 – 5/5 pre-op hx of UTI
Treatment and outcomes of ureter
injuries due to ovariohysterectomy
complications in cats and dogs
B. L. Plater* and V. J. Lipscomb 2020
Fourteen female cats and five female dogs
Five of seven animals with bilateral ureter injury presented with anuria.
Three animals died or were euthanased without definitive surgery. Surgical repair included
ureteroneocystostomy
(eight cats, one dog), ureteronephrectomy (four cats, two dogs), subcutaneous
ureteral bypass placement (three cats) and ureteral stent (one cat)
(44%) that were discharged from the hospital experienced major complications requiring one or
more additional surgeries. Overall outcome was excellent in 13 (68%), poor in 22%
A key indicator of a ureteric injury is an animal failing to recover normally or
becoming unwell shortly after ovariohysterectomy
Ureteroneocystostomy is preferred to ureteronephrectomy to
preserve renal function and is usually a requirement for bilateral
ureteric injuries but carries a high complication rate resulting
in additional surgery (and therefore costs), albeit often with an
excellent final outcome
All seven animals (100%) that had
a major complication had undergone a neoureterostomy surgery
Diagnostic imaging observations in cats
treated with the subcutaneous ureteral
bypass system
H. Dirrig 2020
renal pelvis diameter: median pre-op 9mm (3-28mm); median post-op 3mm (2-23mm)
- SUB abnormalities: 43/81 (53%) - stent obstruction, leakage, non-obstructive kinking
loosened nephrostomy pig-tail loop
- 54% ureters became patent, majority slightly dilated or irregular margins (chronic inflam)
Use of a modified Boari flap for the treatment of a proximal
ureteral obstruction in a cat
Lillian R. Aronson 2018
A modified Boari flap can lead to long-term resolution of
proximal ureteral obstruction in cats, without requiring stents or permanent implants
Gibson 2021 – removal/repositioning of implants with endovascular snare system
- transurethral removal and repositioning, transnephric removal, cystoscopic removal
- retrograde/proximal movement of a whole stent into the renal pelvis of a Newfoundland
reported and into distal ureter in a cat (undersized)
Veran 2022 – transmural GIT migration of SUB devices – 11 devices in 8 cats
- incidence: 1.31% cats, 1.07% SUB devices (from participating institutions)
- median time from placement to migration: 928d (201-2298d)
- dx: ultrasound 6/11, pre-op contrast radiography 2/11, surgery 3/11
- migration: 4 nephrostomy, 7 cystostomy to duodenum (3/11), jejunum (7/11), colon (1/11)
- tx: SUB removal 7, sub-replacement 2 (1 cat 2 migration events)
- GIT resection/anastomosis 7/8 + enterotomy 2
- survival to discharge: 6/8
Schwartz 2022 – review of urinary surgery techniques
- dysuria associated with UVJ in cats > dogs
- cat UVJ located in proximal urethra – stent placement → urethral irritation
- dog UVJ located at trigone
Kendall 2024 – ACVIM consensus statement for urinary incontinence
- cystoscopic-guided ablation preferred for intramural ectopic ureters
→ 47-72% continence without additional medication
- adjunct tx (urethral bulking/AUS/medication) → 77-82%
- concurrent USMI in 47-67%
