Fixed anatomical narrowing of the urethra, with associated spongiofibrosis and scarring of the surrounding corpus spongiosum
The term urethral stricture should technically be limited to the anterior urethra.
Posterior urethra is not surrounded by spongiosum – posterior urethral stenosis is a fixed narrowing of the urethra due to fibrosis
Key anatomical points
Common penile artery is termination of internal pudendal -> 3 x branches; cavernosal arteries, bulbourethral arteries and dorsal arteries
Blood supply to urethra is dual and paired/bilateral – antegrade main supply from bulbourethral arteries and some retrograde supply from branches of dorsal artery which arborises in the glans.
Bulbar urethra is more dorsal within the spongiosum – becomes more central with sponge as moves distally.
Aetiology
Any process which injures urothelium or underlying corpus spongiosum to the point that healing results in a scar can lead to stricture.
Varies by region – meta analysis suggests 1/3 iatrogenic, 1/3 idiopathic, 20 % trauma and 15 % inflammatory
Iatrogenic
- Catheterisation and catheter misadventure
- Prevention – only IDC when necessary, trained staff, reduce IDC time where possible, silicone hydrophilic catheters for ISC
- Transurethral surgery (particularly TUR)
- Predictors of stricture post TUR – prostatic inflammation, resection time, urethral injury, post-op UTI, sheath size, cold fluids
- Radiation
- 5 % patients have EBRT for prostate cancer, 1.9 % brachytherapy, and 5 % combined EBRT-brachy, after 4 years follow up
- Incidence increases with time
- Length of follow up, combination EBRT/brachy and TURP found to increase risk
- Delaying salvage radiation may reduce stricture risk
- Post hypospadias surgery
- Common but a specific entity with altered spongiosum
Traumatic
- Straddle injury – corpus spongiosum is crushed against inferior pubic ramus
- Pelvic fracture causing posterior urethral injuries – shearing against the fixed prostatic urethra with tearing usually at bulbomembranous junction
- During combat or kicks to the perineum
- Unrecognised urethral injury during penile fracture
Inflammatory
- Lichen sclerosis/BXO – might involve the urethra in 20 % of cases
- STIs (gonorrhoea) – historically common cause of stricture
- TB
Idiopathic
- Unrecognised trauma thought to be a likely driver
Malignancy / SCC
- Rare
Pathophysiology
- Normal pseudostratified columnar epithelium is replaced by squamous metaplasia
- Small tears in the metaplastic tissue result in urinary extravasation
- Extravasation causes fibrotic reaction within spongiosum
- Fibrosis may progress to narrow the lumen
- Spongiofibrosis involves deposition of collagen and loss of smooth muscle to collagen ratio in spongiosum
- Severe cases fibrosis may extend beyond the spongiosis
Clinical features
Generally present with either obstructive LUTS or infections (including epididymo-orchitis or prostatitis).
- Post micturition dribble seems to be common.
- Urinary spraying or splitting of stream and dysuria or other pelvic pain.
- Ejaculatory pain or reduced volume.
- Retention or difficult catheterisation.
Assessment:
History
- Duration of symptoms, previous interventions, or instrumentation
- Haematuria, UTIs
- History of trauma
- Medical history, medications, surgical history, previous pelvic radiation
- STIs
- General LUTS history
- Social history including smoking, occupation, and sexual function
Exam
- General exam including BMI, frailty
- Abdominal and genital exam
- ?BXO ?circumcision ?palpable stricture ?meatal stenosis ?palpable bladder ?hypospadias
- DRE
Investigations
- IPSS
- Flow rate and residual (+/- USS KUB)
- Urine culture (+/- cytology)
- Bloods – renal function, +/- PSA
Further assessment of stricture – imaging, scope.
Retrograde urethrogram allows for identification of stricture location, length and degree of narrowing; can also exclude or diagnose other urethral abnormalities like diverticulum or false passage.
- PPV 89 %, NPV 76 %
- Sensitivity 91 %, specificity 72 %
Limitations:
- May be difficult to assess proximal urethra, especially if stricture very narrow (can combine with voiding study to overcome)
- May be affected by degree of penile stretch, pelvic rotation and body habitus.
- Often underreports stricture length.
- Operator dependent.
- Moderately invasive with risks of infection, pain, bleeding and contrast extravasation.
Technique:
- 30 – 45 degrees oblique with something under the hip (sandbag, pillow, 3L bag)
- Lower leg bent, top leg straight. (NB this is in elective setting – trauma/pelvic fracture may be limited in positioning, and may have to rotate C-arm instead)
- 12 Fr IDC with 2 mL in balloon in navicular fossa
- Penis taut on full stretch. Slow injection of 20 – 30 mL of 50 % diluted contrast under fluoro.
- C-arm perpendicular to urethra
- Following by voiding cystourethrogram to complete study.
Cystourethroscopy is useful for confirming the diagnosis.
- Identifies diagnosis and the location and distal calibre but cannot assess proximal to stricture or length.
- Paediatric cystoscopes or ureteroscopes may be useful (also allows assessment of bladder and exclusion of stones etc.)
- Useful for bulbomembranous strictures which can be difficult to assess with RUG.
- May be combined with initial treatment in appropriate patient.
Ultrasound has emerging role in stricture assessment.
- May be better than RUG for estimating stricture length and diagnosis of stricture.
- Incorporation of elastography may provide estimates of spongiofibrosis.
- Operator dependent, requiring advanced training, and not widely available.
- Need distension of urethra with gel, causing discomfort.
- Less useful for bulbar strictures cf. penile urethra.
- May be used intra-operatively by some surgeons.
The goals of work-up are to determine:
- Location of stricture
- Length
- Calibre
- Exclude other urethral disease (other strictures, diverticulum)
- Degree of spongiofibrosis
- Exclude concomitant bladder pathology (stones etc.)