Ch 116 Bladder Flashcards
anatomy
- ventral median ligament (contained the urachus in foetus)
- lateral ligaments: distal portion of the ureter and umbilical artery on each side
- Each ureter tunnels obliquely through the dorsolateral bladder wall before opening into the bladder
- urothelium of the bladder consists of mucosa composed of transitional epithelial cells, and submucosa, which contains connective tissue
- The urothelium is covered by a layer of smooth muscle (detrusor muscle)
- there is no anatomically distinct internal sphincter at the vesicourethral junction
- The serosa is the outermost layer of the bladder
Where is the trigone?
Internal region of the bladder between the ureteral opening and the urethral opening at the bladder neck
micturition
Urinary control is regulated by sympathetic, parasympathetic, and somatic innervation.
- The internal urethral sphincter remains contracted via sympathetic α-adrenergic stimulation from the hypogastric nerves (L1-L4), while β-adrenergic stimulation relaxes the detrusor muscle, allowing urine storage.
- Bladder distention activates stretch receptors, triggering parasympathetic pelvic nerve stimulation (S1-S3), leading to detrusor contraction and urination.
- This activation also inhibits sympathetic control and signals the brainstem to relax urethral musculature.
- The pudendal nerve (S1-S3) provides somatic control over the external urethral sphincter, which maintains urethral resistance during storage and relaxes during reflex urination.
- Voluntary control occurs via pudendal nerve innervation and direct cortical influence on the pontine micturition center.
Not all detrusor muscle cells have direct innervation: transmission of neuromuscular impulses also occurs between one innervated detrusor muscle cell and many adjacent muscle cells. Prolonged bladder distention or bladder fibrosis results in loss of this excitation-contraction coupling; subsequent atony of the detrusor muscle results in urine retention and overflow
Blood Supply and Lymphatic Drainage
- the vascular supply also enters the bladder dorsally.
- The caudal vesical artery is the major arterial supply to the bladder. It arises from the vaginal (females) or prostatic (males) branch of the internal pudendal artery.
- Bladder venous drainage is into the internal pudendal veins, and lymphatic drainage is via the hypogastric and sublumbar lymph nodes.
How long does it take for bladder mucosa to heal?
How long for full-thickness defects to reach full strength?
Mucosa fully heads in 5 days
Full thickness strength in 14-21 days
Suture Material, and Suture Patterns
- absorbable, synthetic suture suitable choices for closure.
- Monofilament suture recommended > less tissue drag than multifilament and fewer bacteria adhere
- Nonabsorbable sutures or staples are not required and could predispose to cystic calculi formation.
- Hickey 2020 found calculi associated with PDS/maxon
- polydioxanone and polyglyconate are acceptable in sterile and E.coli–contaminated urine but that poliglecaprone 25 may not have sufficient tensile strength during the critical phase of bladder healing
- suture size ranges from (3-0 to 5-0)
closure pattern
- there is no consistent evidence as to which performs best overall
- - accurate needle placement through the strength-holding submucosal layer
- A single-layer, full-thickness, simple, continuous, or interrupted appositional closure is quick, provides accurate apposition of the strength-holding submucosal layer, and has not been shown to be inferior to a two-layer, inverting, continuous suture pattern
- compromised bladder > omentalise, serosal patch
barbed suture may be appropriate for cystotomy closure but in vivo studies are needed to support this finding (used in laparoscopy, no knot required)
What suture materials are most appropriate for use in the bladder?
What organism disintegrated all tested sutures by day 7?
Polydioxanone and polyglyconate
Proteus mirabilis
What ABx are a reasonable choice for periop antibiosis in the face of a UTI?
Amoxiclav
3rd gen cephalosporin
Enrofloxacin
antibiosis
- absence of infected urine is classified as clean contaminated.
- The infection rate for this class is approximately 5%
- E.coli, Proteus, Staph
- there does not appear to be a significant risk for affecting an intraoperative positive urine culture result by administering prophylactic antibiotics at induction before surgery
What effects does azotaemia have on anaesthesia and surgery?
- Significant impact on animals ability to tolerate anaesthesia due to alterations of pharmacokinetics of, and sensitivty to, drugs
- Interferes with platelet function
What are the effects of hyperkalaemia?
Bradycardia
Arrhythmias
Potentiates the cardiodepressant effects of anaesthetic drugs
hyperK Tx
- Fluid therapy and bladder decompression or urinary diversion (depending on the cause of the hyperkalemia) are often all that are required to correct hyperkalemia
- severe hyperkalemia, intravenous calcium gluconate, glucose and insulin
diagnostics
cystocentesis
- (C&S, urinalysis, decompress)
catheter biopsy
- applying suction using a syringe via a urinary catheter
- histologic diagnosis in 10 of the 12 dogs
Bladder ultrasonography
- most sensitive
- ultraosund guided biopsy
Positive-contrast cystogram
- reveal the presence of bladder rupture,
- identify radiolucent calculi,
- outline any bladder masses
retrograde urethrocystogram
- lower rupture location is not known.
double-contrast cystogram
- enhanced mucosal detail (lesions, masses, calculi)
intravenous urogram
- Computed tomography (CT) excretory urography
cystoscopy
- direct, magnified view of the mucosal surfaces of the bladder and urethra.
- allows retrieval of calculi or biopsy of bladder tissue, lithotripsy of bladder calculi, laser ablation of ectopic ureters, submucosal injection of collagen
List the options for contrast radiographs for the work-up of suspected urolithiasis
Cystogram
Retrograde cystourethrogram
Double contract cystogram
Intravenous urogram
Cystotomy
- There is no difference urine leakage, adhesions, or calculi formation between dorsal or ventral cystotomy approaches
- cystotomy vs LAC: - Results suggested that LAC may be an acceptable minimally invasive technique for treatment of cystic calculi in dogs. Surgery times were similar to those for dogs undergoing OC; however, surgical and total procedural costs were higher. Further investigation is suggested to determine which patients may benefit from LAC versus traditional OC
What is the reported rate or uroabdomen after cystotomy?
less than 1.5%
Haematuria and dysuria in 37-50%
Cystectomy
- a temporary cystostomy tube or an indwelling urethral catheter may be placed to maintain bladder decompression
- ureteral orifices, then the ureter can be transected and reimplanted
- neurovascular supply to the bladder enters dorsally in the trigone region
What cause bladder regeneration after cystectomy?
- Mucosal regeneration, synthesis and remodelling of scar tissue
- Hypertrophy and proliferation of smooth muscle
- Distention of remaining bladder wall
Regenerating cells arise from the epithelium of the terminal ureters and urethra (trigone)
How much bladder can be removed in dogs?
30-40% - all dogs regained baseline bladder capacity by 10m
More than 90% - Still had 72% decrease in capacity by 9m
40-70% excised in 11 dogs, 2 had persistant pollakiuria
List options for reconstructions when most or all of the bladder required excision
- Seromuscular colonic augmentation (the external wall of the colon became the cranial wall of bladder)
- Ileocystoplasty
- Total cystectomy with urinary diversion to colon (not recommended, high morbidity)
- TOtal cystectomy with diversion to prepuce or vagina
- Porcine SIS (experimental, successful for 40%)
Cystostomy
- traditionally placed surgically via a ventral midline laparotomy. A Foley or mushroom-tipped catheter (8 to 14 Fr) is placed for short-term use. Foley not recommended for long-term use because the balloon may deflate over time > bladder is pexied to abdo wall
- alternative for long-term use is a low-profile silicone human gastrostomy tube
- a minimally invasive inguinal approach is simple and effective for cystostomy tube placement and can usually be performed in under 15 minutes (Bray 2009)
- tube must remain in place for at least 7 days to allow time for a secure adhesion to form between the bladder and body wall.
- Ultrasound-guided placement of a pigtail cystostomy tube may be beneficial as it is not technically challenging, can be performed rapidly, and may avoid the need for general anesthesia (Culler 2019)
What approaches can be used for cystostomy tube placement?
Ventral midline
Minimally invasive inguinal approach
Laparoscopic
What % of patients with cystostomy tubes develop complications?
49%
Inadvertnent removal, displacement, chewing, breakage of mushroom tip on removal, fistula formation, urine leakage, rectal prolapse etc