LA Urolithiasis: Medical/Surgical Management and Complications Flashcards
what are the goals of medical versus surgical therapy? what do they include?
medical:
-stabilize patient
-dissolve existing calculi
-prevent formation of additional stones
-include: analgesics, antimicrobials, urine acidifers (tetanus prophylaxis!!)
surgical:
-urine drainage
-remove excess calculi
-re-establish urethral patency
-include: cystoscopy, urethrotomy/perineal urethrotomy (PU) in males, lithotripsy (mechanical, laser, shock wave)
management changes long term!
describe cystoliths in horses
- presenting complaint:
-typically hematuria mid or end stream, especially after exercise - clinical signs: hematuria, stranguria, oliguria, incontinence, urine scald, weight loss
- typically calcium carbonate, calcite (mineralized form)
-TI: soft, yellow, spiculated stones of CaCO3 crystals
-TII: <10% of calculi, smooth, rounded white (Ca, carbonate, P, Mg) - calculi most commonly in the bladder of the horse!!
- majority cases: males >8 years of age
describe considerations for surgery for uroliths in horses
- gen anesthesia or standing sedation
- perioperative analgesia: systemic and local (epidural)
- antimicrobials
- complications
- recurrence (especially if leave nidus behind (lithotripsy-punch until it shatters))
describe surgical approaches for removing bladder stones in horses
- mare lithotripsy, endoscopic bag removal
- gelding progressive urethral dilation via perineal urethotomy
- laparascopic removal: in standing horse; size limitations
- modified parainguinal approach: for larger stones, require general anesthesia
- pararectal cystotomy
describe what the bladder needs re: surgery
bladder requires water tight seal!
single layer closure recommended:
-achieves anatomic reconstruction
-accelerates healing
-obviates reduction in luminal diameter
-achieves water tight seal
potential complications:
1. incisional infection
2. dehiscence
3. difficult access
4. incision: mucosal defects heal in 5 days and full thickness defects heal in 14-21 days
5. cystolith removal tends to be incomplete :( lots of dust and debris can act as nidus for infection or future stone formation
describe potential surgical complications
- difficult exteriorization of bladder
- prolonged manipulation/bladder fatigue
- loss of stone architecture: incomplete removal
- tension in closure - can dehiss
describe follow-up care from cystotomy
- indwelling urinary catheter and abdominal drain
- broad spectrum antimicrobials (penicillin, gentamicin)
- anti-inflammatories: flunixin, IV lidocaine CRI
- IV fluid therapy
- serial metabolic panels
- serial abdominal ultrasounds
describe ultrasound for bladder stones in horses
a beneficial diagnostic!
renal and ureters: check them both
10% calculi at more than one location
how are larger calculi best removed?
through a parainguinal, caudal midline, or pararectal approach
-incisional infection or dehiscence and difficult accessa re known complications
what type of inflammation does urine cause?
nonseptic/sterile neutrophilic inflammation: because chemical irritant
-cell count: >5000 NC per ml
-specific gravity: >1.025 (hypersthenuric)
-total solids: >3.0 g/dL
describe urolithiasis in ruminants
- formation of stones within urinary tract
-leading cause of obstruction!! - very common due to dietary imbalances
- all species affected
- males predisposed: long urethra, small diameter urethra
- castrated males predisposed:
-urethral diameter is influence by testosterone, so if a pet goat, delay castration (the longer the better)!
compare and contract partial and complete obstruction in ruminants
partial:
-dribbling when urinating
-small, frequent urinations
-medial or surgical management
complete:
-no urine produced
-surgical EMERGENCY
describe early and late signs of urolithiasis in ruminants
early signs:
1. hematuria
2. dysuria
3. crystals on prepuce
4. dribbling
5. tail flagging
6. colic
late signs:
1. anorexia
2. depression
3. prepucial swelling
4. abdominal distension
5. recumbency
6. seizure activity
7. death
describe diagnostics for urolithiasis in ruminants
plain view radiographs helpful for radiopaque:
-calcium carbonate
-calcium oxalate
-silica
describe options for surgical management of obstruction in ruminants
- urethral process amputation:
-#1 place for obstruction in small ruminants
-no effect on future fertility in breeding males
-exteriorization is the hardest part! - bonnano-pre-pubic catheter
- perineal/ventral urethrostomy
- tube cystotomy +/- urethrotomy
- bladder marsupialization
- lithiotripsy
describe the goals of surgical management of urolithiasis in ruminants and complications
immediate/short term:
-relieve obstruction: pain relief, stop spasm, allow other urethral stones to pass
-temporary or permanent rerouting of urine
longterm: maintain normal urinary and breeding function
complications: make worse prognosis (duh)
-bladder rupture
-urethral rupture
-hydronephrosis
describe urethral rupture
- trauma from stones: ischemic necrosis (leads to sloughing) from sharp stones
- usually due to chronic obstruction
- swollen prepuce: pitting edema
- poor prognosis: urethral stricture
describe emergency workup for urolothiasis
signalment: age, male, castrated or intact
history: onset, duration, clinical signs, waxing and waning, prior treatment
exam: TPR, attitude/mentation
-abdominal palpation: bladder, free fluid, ballottement
-rectal palpation: urethral dilation, pulsation
-prepucial evaluation: swelling?
imaging:
-radiographs: stones and location
-ultrasound: free abdominal fluid? eval bladder (size and stones), eval kidneys (hydronephrosis?)
-abdominocentesis: creatinine
-EKG: arrhythmias due to potassium
describe urethral process amputation
-#1 place for obstruction in small ruminants
-no effect on future fertility in breeding males
-exteriorization is the hardest part!
advatanges:
-quick, cheap, easy
-GA not required, sedation with local block
-abdominal cavity not opened
disadvantages:
-short term fix: most stricture within 6 months
-hemorhage
-urine scalding
describe perineal urethrostomy
- salvage procedure: not an option for breeding animal
- incise skin, dissect down to penis, suture urethra to skin
- stricture common
- modified proximal for goats: transection of ischiocavernosis muscles; low rate of stricture formation
- these are pretty expensive surgeries
describe tube cystotomy
advantages:
-goal: functional urethra/penis
-necessary for breeding males
-permits bladder repair
-best/gold standard option!
-only 75% success rate though :(
disadvantages:
-abdominal surgery
-general anesthesia
-more difficult and time consuming (expensive!)
-longer recovery
-cystitis
goals:
-provide urine egress: urethral relaxation, stone dissolution with ammonium chloride and renacidin
-challenge the animals: close tube, let them try to urinate and see if they can and repeat until they can
-tube can stop functioning during procedure = annoying
success:
-mean time to normal urination: 11 days
-76% successfully treated
-re-obstruction in <20% of animals within 12 months
-concurrent medical management!
-dietary modifications
-ammonium chloride
-IV fluid therapy if needed
describe percutaneous tube cystotomy
- percutaneous suprapubic balloon catheter
-trocar tip
-inflatable ballon
-cheaper than tube cystotomy! - can be introduced with sedation
-ultrasound guidance helpful
-the bigger the bladder the easier (complete obstruction easier than partial) - disadvantage: unable to manually remove cystoliths
describe bladder marsupialization
- stoma created between bladder and body wall
- provide urine egress permanently
advantages: quick fix
disadvantages:
-chronic cystitis
-urine scald
-abdominal surgery
last resort!
not viable for breeding males!!
describe urethral catheterization
diverticulum interferes with retrograde catheterization in ruminants!
bern catheter: bent tip facilitates passage of diverticulum
more likely to traumatize urethra though
