Blocked bladder

• Causes Of blocked bladders - physical obstruction

  Uroliths

  Strictures

  Debris

  Inflammation or an inflammatory plug secondary to FIC.

  Prostatic disease

  Neoplasia is less common.
• Causes Of blocked bladders - functional obstruction

  Detrusor atony.

  UMN - thoracolumbar disease

  Possible spasm of the urethra (associated with idiopathic feline cystitis).
• The clinical examination of the blocked bladder will usually include

  A large, turgid, palpable bladder - usually can’t express it, this can be difficult to feel in detail in the large dog or the fat cat so do not always rely on this despite it being a main sign.

  A history from the owner of not noticing the animal urinating - stranguria, oliguria and anuria

  Bradyarrythmia - due to the high potassium, however if potassium is not built up then may get tachycardia

  Lethargic - collapsed

  Caudal abdominal pain.
• What is the main cause of decompensation and death in blocked animals?

  Potassium build up

  • Hyperkalaemia - more than 7-8mmol/l

  As it causes cardiac arrythmias and may stop the heart from beating.
• Avoiding Hyperkalaemia - haematology and biochemistry

  Identify electrolyte abnormalties and the acid-base state (metabolic acidosis is most likely as the hydrogen ions are not being excreted via the urine).

  • To assess the degree of postrenal and renal azotaemia: reduced renal blood flow and glomerular filtration rate -> azotaemia, hyperkalaemia, metabolic acidosis.
• Avoiding Hyperkalaemia - imaging the bladder

  Imaging can aid in identifying the cause e.g. radiography to indentifying radiopaque calculi or an extra-urethral mass and retrograde urethrography or ultrasound to identify soft tissue lesions and radiolucent uroliths. This is better suited for further diagnostics
• Avoiding Hyperkalaemia - cystocentesis

  Relieves pressure from the cat and then you can analyse the sample

  • Insert the needle slowly to reduce the risk of bladder rupture.
  • C&S, dipstick and sediment exams can be done as further diagnostics.
  • Do not use antibiotics when a catheter is in place as catheter contamination can affect the results of the culture.
• ECG with Hyperkalaemia

  Changes are sequential with increasing levels of patssium.

  • Peaked T waves
  • Reduced R wave amplitude, prolonged PR interval, reduced QT interval.
  • Reduced P wave amplitude, then widened P waves, then absent (atrial standstill).
  • Widening of the QRS and bradycardia
  • Ventricular fibrillation
  • Asystole

  
• Treatment of blocked bladder - over view

  IV fluids e.g. Hartmann’s (correct acid/base) or 0.9% saline

  Pain relief:

  • No NSAIDs, instead use opioids e.g. buprenorphine or methadone.
  • Not much difference between these in dogs but methadone is more potent in cats.
• Treatment of blocked bladder - correction of acid/base and/or electrolytes.

  Calcium gluconate can stabilise the cardiac potential. Be sure to monitor the ECG throughout and if the bradycardia worsens slow the infusion.

  Insulin drives potassium to enter the cells (give glucose to support this to prevent hypoglycaemia)

  Bicarboniate and beta-agonists.
• Treatment of blocked bladder - remove the bloackage

  Urethral catheterisation, IV catheters for distal blockages, cystostomy.

  • Urethral catheterisation reveals level of obstruction and often allows relief of obstruction by retrohydropulsion. Sedate with midazolam and alfaxalone (diluted 1:4 and given to effect), you may need GA.
• General stone removal - basket retrieval to remove the stones

  A small scope is inserted into the urethra, and a laser is used to break up the stones into smaller precise which then may pass through the urethra.

  Not possible in male cats
• General stone removal - laser lithotripsy

  A small scope is inserted into the urethra, and a laser is sued to brea up the stones into smaller pieces which then may pass through the urethra.

  Not possible in male cats.
• General stone removal - surgery

  The bladder is opened through the abdomen, and the stones are removed. However this may damage kidney function.