Surgery of the Ureters in Small Animal Surgery

Surgery of the Ureters in Small Animal Surgery

VMS 5649

Ureters Overview

• Paired Structure: The ureters are a pair of tubes that transport urine from the kidneys to the bladder.

• Location: Found in the retroperitoneal space.

• Function: Responsible for transporting urine.

• Surgical Diseases:

  • Ureter ectopica

  • Ureterocele

  • Trauma

  • Obstruction

• Surgical Procedures:

  • Neoureterocystostomy

  • Neoureterostomy

  • Ureterotomy

  • Ureteroureterosotomy

Ectopic Ureter

• Definition: Ectopic ureters terminate in an abnormal location, which can be alternative locations such as the neck, urethra, or vagina.

• Occurrence: Can occur unilaterally or bilaterally (bilateral is more common).

• Associated Abnormalities: Often associated with other conditions such as:

  • Hydroureter

  • Small or absent kidney

  • Pelvic bladder

Signalment

• Breed Predisposition: Certain dog breeds are more prone:

  • Siberian Husky

  • Labrador Retriever/Golden Retriever

  • West Highland Terrier

• Sexual Predilection: More common in female canines; rare in cats. In cats, there is no significant breed or sex predilection, characterized as extramural.

• Age: Young patients are typically affected.

• Clinical Signs:

  • Incontinence

  • Fails to house train

  • Presence of urinary tract infections (UTI)

  • Urine scalding

Diagnosis

• Diagnostic Tools:

  • Excretory Urography: 76% accurate in diagnosing ectopic ureters.

  • Pneumocystography: Helps visualize anatomy.

  • Excretory Fluoroscopy: Provides real-time imaging.

  • CT Scan: Offers detailed imaging.

  • Ultrasound: Useful for identifying abnormalities.

  • Cystoscopy: Direct visualization and assessment.

  • Male Patients: Often utilize contrast-enhanced CT.

  • Female Patients: Cystoscope is commonly used during examination.

Ectopic Ureter Classification

• Extramural Ectopic Ureters:

  • Less common; enter into the neck, urethra, or vagina.

• Intramural Ectopic Ureters:

  • Enter normally into the bladder but exit abnormally; more common in dogs.

Neoureterocystostomy

Extramural Procedure

• Description: Meant for ureters that enter abnormally.

• Surgical Steps:

  • A surgical approach to reposition ureters that enter incorrectly.

Intramural Procedure

• Description:

  • Performed on ureters entering normally but exiting abnormally.

• Surgical Steps:

  1. Perform cystotomy to access the bladder.

  2. Identify the ureteral entry.

  3. Create a new stoma for ureteral reentry into the bladder.

  4. Suture the mucosa of the ureter to the mucosa of the bladder (mucosa to mucosa).

  5. Catheterize the ureter and ligate the area.

  6. Carefully remove the catheter and tighten sutures.

  7. Dissect out the ureteral remnant that is not functioning.

Cystoscopic Laser Treatment

• Purpose: For managing intramural ureters.

• Benefits:

  • Similar success rates to other methods.

  • Decreases postoperative pain.

• Limitation: Cannot remove the remnant ureter that may contribute to incontinence.

Prognosis

• Outcome:

  • Other functional abnormalities may still exist post-procedure.

  • Incontinence improves in approximately 60% of cases.

  • Improvement can reach up to 90% when medications such as Phenylpropanolamine (PPA) are added.

Ureterocele

• Definition: Condition characterized by the dilation of the distal ureter due to a persistent membrane from embryonic development.

• Predisposition: No sex or breed favoritism noted.

• Classification:

  • Intravesicular: Normal positioning within the bladder.

  • Ectopic: Abnormal placement at the neck or urethra.

• Clinical Signs:

  • Presence of urinary tract infections (UTI)

  • Incontinence

  • Azotemia if obstruction is present.

Diagnosis

• Tools:

  • IV Urography: Characteristic "cobra head" sign indicating the presence of a ureterocele.

  • Ultrasonography: effective in detecting dilation.

Treatment

• Intravesicular Ureterocelectomy: Removal of the ureterocele within the bladder.

• Ectopic Ureterocelectomy: Neoureterocystostomy along with ureterocelectomy to address the ectopic condition.

Ureteral Trauma

• Etiology:

  • Primary cause is iatrogenic (related to surgical or medical treatment).

  • Other causes include blunt trauma and obstruction.

• Clamp Injury:

  • Studies show 41% of crush injury sites did not resolve within 60 minutes.

• Surgical Indications:

  • Required if there is leakage from the ureter.

  • If blood supply to the ureter is damaged.

  • If obstruction is evident.

• Diagnosis:

  • Identify conditions like uroretroperitoneum or uroabdomen using radiographs and IV urography to localize the lesion.

Treatment

• Approach: Based on the timing, location, and severity of the injury.

• Options:

  • Nephroureterectomy to remove the affected ureter and kidney.

  • Ureteroureterostomy (ureteral anastomosis).

  • Neoureterocystostomy (ureteral reimplantation).

  • Urinary diversion techniques.

Ureteroureterostomy

• Description: Procedure of choice for proximal ureter when reimplantation is not possible.

• Challenges:

  • Requires magnification and is extremely difficult to perform.

  • High incidence of complications such as strictures and dehiscence.

  • Catheterization through cystotomy helps avoid complications with back wall angulation.

Urinary Diversion

Ureteral Stent

• Description:

  • A catheter left proximal to the anastomosis, extending through the bladder to the urethra.

  • Suture the catheter to prepuce or lip of vulva.

  • Remove catheter in 5-7 days; controversy exists surrounding its use.

Nephrostomy Tube

• Function: Used to divert urine after ureter surgery, hydronephrosis, or obstruction.

• Implantation:

  • Fenestrated tube is passed through the kidney to the renal pelvis, placed outside the patient.

  • Ensure a closed system is maintained during the procedure.

Transureteroureterostomy

• Indication: Utilized when the proximal ureteral length is insufficient to reach the bladder but long enough to cross the midline.

• Procedure: A segment of the ureter is brought across the midline and anastomosed to the other ureter for urine drainage.

Strategies for Loss of Ureter Length

• Renal Descensus: Mobilize the kidney and suture it caudally to the lumbar musculature.

• Nephrocystopexy: Suture the kidney to the cranial edge of the bladder to maintain position.

• Psoas Hitch: Technique to fix the bladder in a more cranial position.

Bladder Wall Flap

• Indication: Significant loss of distal ureter necessitates advanced technique.

• Procedure: Elevate a flap of bladder and implant the ureter into the end of the elevated flap, creating a tubular structure and closing the defect.

Ureterolithiasis

• Definition: The most common condition leading to ureteral surgery, primarily affecting cats.

• Occurrence: Unilateral cases are more common.

• Clinical Signs:

  • Asymptomatic in early stages

  • UTI, hematuria, anorexia, lethargy, and pain become evident as the condition progresses.

• Diagnostic Imaging:

  • Radiographs: Show radiopaque stones such as calcium oxalate.

  • Ultrasound: Aids in determining dilation of ureters and renal pelvis.

Medical Management

• Dissolution: Medical dissolution is not possible due to most stones being calcium oxalate, which do not dissolve well in urine.

• Fluid Therapy:

  • Administer IV fluids and diuretics to increase urine flow.

  • Serial monitoring with radiographs and ultrasound for up to 2 weeks.

• Muscle Relaxers: Use of glucagon, calcium channel blockers, or amitriptyline may relax smooth muscle to facilitate stone passage.

• Surgery Indications: Indications for surgery or lithotripsy include:

  • Complete obstruction

  • Azotemia

  • Pyelonephritis

  • Failure of medical treatment after 2 weeks.

Pre-surgical Considerations

• Obstruction Duration: It is difficult to predict how long the ureter has been obstructed.

  • After 1 week of obstruction, Glomerular Filtration Rate (GFR) drops below 65%.

• Kidney Recovery: It is challenging to anticipate kidney recovery after obstruction.

• Pre-existing Conditions: Most cats have interstitial nephritis unrelated to the obstruction prior to treatment.

• Complication Rates: High risk of complications associated with surgery, particularly with azotemic cats having bilateral renal disease.

Treatment Options

• Cystotomy and Retrograde Flushing: Employed with subsequent removal via pyelithotomy.

• Ureterotomy:

  • Longitudinal incision made in the ureter.

  • Lavage the ureter and perform either transverse or longitudinal closure.

  • Nephrostomy drainage may be utilized as needed.

Permanent Ureteral Stenting

• Advantages:

  • Decreased morbidity and shorter hospitalization.

  • Fewer complications observed.

• Disadvantages:

  • Requires specialized equipment and has a steep learning curve.

  • Expensive and technically difficult to perform.

• Indications:

  • Commonly used for stones, tumors, strictures, or blood clots.

• Techniques:

  • Can be performed endoscopically, or surgically via the SUB (subcutaneous ureteral bypass) technique.

Endoscopic Placement

• Patient Demographic: Suitable for female dogs/cats or male dogs weighing over 8kg.

• Procedure:

  • General anesthesia required.

  • Use fluoroscopy and guidewire, followed by ureteral catheterization.

  • Contrast media is injected to visualize the pelvic area.

  • Insert ureteral stent aided by a pusher catheter.

Surgical Stenting

• Dogs: Performed through a distal cystotomy approach.

  • Similar procedure to endoscopic but no pusher catheter required.

• Cats: Usually placed in an antegrade method.

Subcutaneous Ureteral Bypass (SUB)

• Components: Includes a port with silicone diaphragm for patient care and monitoring.

• Functionality: Allows for sampling if needed and can alleviate obstruction issues via port access.

• Maintenance: Requires flushing every 3-6 months to ensure functionality and prevent clogs.