Subjectively large herniation of the bladder urothelium through the muscular bladder wall – resulting in a thin walled, urine filled structure adjacent to and connecting to the true bladder lumen.
Histologically there is urothelium and subepithelial lamina propria, but no true muscle layer and maybe only sparse scattered thin muscle fibres.
A fibrous capsule or pseudocapsule may be present.
Classification
Congenital
- Usually solitary and usually in boys < 10
- Lateral and posterior to UO, usually associated with VUR
- Generally thought to be a congenital weakness of the detrusor muscle
- Usually present with UTI
- Typically thin walled bladders without trabeculation
- No identified association with malignancy
- Often found in associated with congenital syndromes
- If treating childhood diverticulum with reflux, probably needs re-implant
Acquired
- Usually in the setting of BOO or neurogenic bladder neck dysfunction
- Most commonly adjacent to UO, but can be anywhere
- Often multiple of varying sizes (cf. one if congenital)
- Much more common in males 9:1
- Bladder typically trabeculated
- “Hutch” diverticulum – superior and lateral to UO not involving trigone, initially described in setting of neuropathic bladder and VUR
- Iatrogenic diverticulum – herniation through or adjacent to cystotomy closure
Presentation & work-up
- Because large bladder diverticula empty poorly and incompletely during voiding (due to lack of detrusor muscle contraction) – most signs and symptoms relate to urinary stasis.
- Occasionally if very large may present with symptoms due to mass effect.
- Can be found incidentally on imaging or cystoscopy.
- Usually found during investigation of LUTS, UTIs or haematuria.
Usual LUTS history (don’t forget UTIs, neurological symptoms or possibility of neuropathic bladder).
Examination including DRE
Investigations:
- Urinalysis and urine culture
- Urine cytology (usually)
- Bladder diary
- IPSS
- Ultrasound – residual volume, check kidneys and exclude hydronephrosis
- CT IVP – confirm diagnosis with contrast into diverticulum, check kidneys
- Cystogram – if unclear diagnosis from other imaging
- VCUG – especially in children if investigating concurrent reflux
- May show during voiding urine is moved from bladder to diverticulum, which enlarges during voiding
- Urodynamics
- Bladder outlet obstruction – either confirm suspicion or assess for occult obstruction or DSD
- Contractility
- Cystoscopy
- Entire diverticulum should be inspected – may need flexible cystoscopy
- Look for tumour, stones, neck
- Any abnormal mucosa needs careful biopsy – no muscle layer
Risk of cancer
Potentially increased risk of malignancy within diverticula – due to urinary stasis and chronic inflammation.
Prevalence of cancer within diverticulum ranges 0.5 – 10 %
70 – 80 % TCC, then 20 – 25 % SCC.
More likely to be invasive – no muscle layer – rapid progression to extravesical/T3 disease and also risk of dissemination during biopsy/TURBT.
Managing concurrent BOO
The outlet obstruction (or neurogenic DSD etc) needs to be treated at the same time or prior to the diverticulum.
Options include:
- TURP initially and see if symptoms settle
- May reduce bladder pressures enough that diverticulum is able to empty
- May fix bothersome symptoms for patient
- Concomitant diverticulectomy and open prostatectomy
Management options for bladder diverticulum
Non-operative management and observation reasonable in patient with little or no symptoms.
Should be informed of potential risk of malignancy (which may be aggressive), need for ongoing follow up and periodic surveillance
Surveillance regime poorly defined – should involve symptom review, consider urine studies including cytology and endoscopic evaluation
If poor emptying and UTIs are the problem, and not fit or willing for diverticulectomy, intermittent self catheterisation can be useful.
Still consider periodic surveillance with cytology and cystoscopy.
Indications for surgical intervention:
- Symptoms – poor emptying
- Recurrent UTIs
- Stones within diverticulum
- Cancer in diverticulum
- Ureteric reflux or obstruction
Endoscopic management – resection or incision of the neck of diverticulum, or fulguration of urothelium within diverticulum
Bladder diverticulectomy (combined intravesical/extravesical approach – good for large diverticula)
- Consider cystoscopy first – looking for stones, tumours, location of neck of diverticulum, proximity to UOs (place catheters/stents early if close).
- Supine with break. IDC with filling line.
- Lower midline, develop extraperitoneal/retropubic space. Fill bladder.
- Vertical cystotomy (essentially bivalving the bladder) between stay sutures.
- Locate UOs and place ureteric catheters/feeding tubes.
- Locate diverticulum and diathermy through urothelium circumferentially around
- Finger in diverticulum and push out – bringing neck of diverticulum extravesically
- Alternative is pack diverticulum with Raytec, or IDC with balloon inflated
- Dissect off perivesical tissue around diverticulum
- Diathermy neck of diverticulum from outside with finger in from inside bladder and excise diverticulum
- Can strip away mucosa from fibrous pseudocapsule
- Or ?excise entire pseudocapsule if safe
- Close bladder in 2 layers ensuring muscular apposition to prevent recurrence
- Drain
- IDC for 10 days with cystogram prior to removal
Purely intravesical approach may be used for smaller diverticula – grasp the base of the diverticulum with Allis or Babcock and invaginate into bladder, then circumscribe and diathermy the neck with it everted, then close the bladder.