Urethral Stricture & Urological Trauma
Surgery · Urology · lean revision notes
Urethral Stricture & Urological Trauma
A combined high-yield block covering urethral strictures (gonococcal and traumatic), the imaging duo of RGU/MCU, and the spectrum of urological trauma — renal (AAST grading), ureteric, bladder (intra- vs extraperitoneal rupture) and urethral injuries. NEET PG loves applied anatomy and the "which investigation/which management first" angle here.
Urethral anatomy — the foundation
The male urethra (~18–20 cm) is divided into anterior and posterior parts by the urogenital diaphragm (perineal membrane).
| Segment | Part | Sub-parts | Surrounded by |
|---|---|---|---|
| Posterior urethra | Above UG diaphragm | Prostatic + Membranous | Prostate, external sphincter |
| Anterior urethra | Below UG diaphragm | Bulbar + Penile (spongy) + Fossa navicularis | Corpus spongiosum (Buck's & Colles' fascia) |
- Membranous urethra = shortest, narrowest fixed part, traverses the external (rhabdo)sphincter → most vulnerable in pelvic fracture.
- Bulbar urethra = commonest site of anterior injury (straddle/astride trauma) and of inflammatory (gonococcal) stricture.
- Fossa navicularis and external meatus = sites for instrumentation/catheter-related strictures.
High-yield: Anterior urethral injury → blood at meatus + butterfly/perineal haematoma (Colles' fascia). Posterior urethral injury → "high-riding" floating prostate on PR + pelvic fracture.
Urethral Stricture
Definition & classification
A urethral stricture is a fibrotic narrowing of the urethral lumen due to spongiofibrosis of the corpus spongiosum, producing reduced urinary flow. (Strictly, "stricture" refers to the anterior urethra; posterior narrowing after trauma is called a distraction defect/stenosis, not a true stricture.)
By aetiology:
- Inflammatory — classically gonococcal urethritis (post-infective bulbar stricture), TB, lichen sclerosus (BXO).
- Traumatic — straddle injury (bulbar), pelvic fracture (membranous), iatrogenic.
- Iatrogenic — most common cause overall today: traumatic catheterisation, TURP, cystoscopy, prolonged indwelling catheter.
- Congenital — rare.
- Idiopathic — large proportion in young men.
High-yield: Worldwide the commonest cause of stricture today is iatrogenic/instrumentation; historically gonococcal. Commonest site = bulbar urethra.
Pathophysiology
Injury/infection of the urethral epithelium → exposure of corpus spongiosum → fibroblast proliferation → spongiofibrosis. The depth/length of fibrosis determines treatment success. Lichen sclerosus (BXO) is an immune-mediated dermatosis causing meatal/penile strictures; it is premalignant (SCC risk) and notoriously recurrent.
Clinical features
Stepwise picture → decreased force/calibre of stream → splaying/forking of stream → straining/hesitancy → terminal dribbling → sense of incomplete emptying → eventually retention.
Complications signal advanced disease (below).
Investigation of choice
Retrograde Urethrogram (RGU) ± Micturating Cystourethrogram (MCU/VCUG) is the gold standard to define site, length, number and calibre.
| Study | How done | What it shows best |
|---|---|---|
| RGU (Retrograde) | Contrast injected per meatus, oblique view | Anterior urethra; defines distal end of stricture |
| MCU/VCUG (Antegrade) | Bladder filled (suprapubic/catheter), patient voids | Posterior urethra; defines proximal end |
| Combined RGU + MCU | Simultaneous | Total length of a tight/obliterated stricture (esp. post-traumatic distraction defect) |
- Uroflowmetry: classic plateau-shaped (box-like) flow curve, Qmax <10–15 mL/s.
- Sonourethrography: measures spongiofibrosis depth.
- Cystourethroscopy: direct visualisation.
High-yield: RGU defines the distal limit, MCU the proximal limit. For a near-obliterated post-traumatic membranous defect, do both together (up-and-down-o-gram) to measure the gap before urethroplasty.
Management / DOC
Treatment depends on length, location and number:
- Urethral dilatation — oldest method; for short, soft strictures. High recurrence; risk of false passage. Filiform-and-follower or metal bougies.
- Direct Vision Internal Urethrotomy (DVIU / Optical urethrotomy) — endoscopic cold-knife incision (usually at 12 o'clock). Best for single, short (<1.5–2 cm), bulbar strictures without dense fibrosis. Good first attempt; success falls with repeats.
- Urethroplasty — definitive, highest long-term success (>85–90%):
- Anastomotic (excision + primary anastomosis, EPA) — for short (<2 cm) bulbar strictures; best results.
- Substitution urethroplasty — for longer strictures using buccal mucosa graft (graft of choice) or penile skin flap.
- Suprapubic cystostomy — temporising for acute retention when urethra cannot be negotiated.
High-yield: Repeated dilatation/DVIU for a recurrent stricture is futile — after one failed DVIU, offer urethroplasty. Graft of choice for substitution = buccal mucosa.
Mnemonic for stricture management ladder: "Don't Damage Urethra Sometimes" → Dilatation → DVIU (urethrotomy) → Urethroplasty → Suprapubic diversion (rescue).
Complications of stricture
Periurethral abscess, urethral fistula/diverticulum, "watering-can perineum" (multiple perineal fistulae), recurrent UTI, epididymo-orchitis, hydronephrosis/back-pressure renal failure, bladder stones, and SCC of urethra (chronic stricture/BXO).
Urological Trauma
A. Renal trauma
- Commonest injured urinary organ in blunt trauma. Most (~90%) are blunt (RTA, fall, sports) and managed non-operatively.
- Suspect with flank pain, flank ecchymosis, gross or microscopic haematuria (degree does NOT correlate with severity).
Investigation of choice = CECT abdomen with delayed (excretory/nephrographic) phase in a haemodynamically stable patient — grades injury and shows urinary extravasation/collecting-system involvement.
High-yield: Indication to image in adults = gross haematuria, OR microscopic haematuria **with shock (SBP <90)**, OR mechanism (deceleration). In children, image for any haematuria (>50 RBC/hpf) because kidneys are relatively larger/less protected.
AAST renal injury grading (2018 update)
| Grade | Injury |
|---|---|
| I | Subcapsular haematoma, no laceration / contusion |
| II | Perirenal haematoma confined to Gerota's fascia; laceration <1 cm depth, no urinary extravasation |
| III | Laceration >1 cm, no collecting system involvement / extravasation; (also vascular injury contained) |
| IV | Laceration into collecting system (urinary extravasation); OR segmental/main vessel injury with contained haematoma; renal pelvis/UPJ injury |
| V | Shattered kidney; OR avulsion of renal hilum (devascularised kidney); main renal artery/vein laceration |
High-yield: Collecting-system involvement (urine leak) = Grade IV. Shattered kidney or hilar avulsion = Grade V. Most grade I–IV blunt injuries → conservative management; absolute indication for surgery = haemodynamic instability/expanding pulsatile haematoma.
Management flow → Stable → CECT, grade, observe (bed rest, serial Hb, repeat imaging) → urinoma/persistent leak → DJ stent; ongoing bleed → angioembolisation; unstable/laparotomy with expanding/pulsatile haematoma → exploration ± nephrectomy.
B. Ureteric trauma
Rare; mostly iatrogenic (gynae/pelvic surgery, ureteroscopy). Penetrating > blunt for external trauma; deceleration can cause UPJ avulsion in children. Diagnosis: CT urogram/delayed films. Management depends on level: ureteroureterostomy (upper/mid), ureteric reimplantation (Boari flap / psoas hitch) for lower-third injuries.
C. Bladder trauma — extraperitoneal vs intraperitoneal
- Almost always with pelvic fracture (extraperitoneal) or a full bladder + lower-abdominal blow (intraperitoneal, dome ruptures).
- Triad: suprapubic pain, gross haematuria (>95%), inability to void.
- Investigation of choice = CT cystography (or retrograde stress cystogram) — bladder filled with contrast, films during filling AND post-drainage (post-drain film catches posterior leaks).
| Feature | Extraperitoneal | Intraperitoneal |
|---|---|---|
| Frequency | Commoner (~60–80%) | Less common |
| Mechanism | Pelvic fracture, anterolateral tear | Blow to full bladder; dome rupture |
| Population | Adults with pelvic # | Children, intoxicated adults |
| Cystogram | Flame-shaped/feathery extravasation into pelvis | Contrast outlines bowel loops / paracolic gutters, "comma sign" |
| Management | Conservative — catheter (Foley) drainage 10–14 days, then cystogram | Surgical repair (laparotomy + 2-layer closure) |
High-yield: Extraperitoneal bladder rupture → catheter drainage (conservative). Intraperitoneal → operative repair. Exception: extraperitoneal needs surgery if bladder-neck involved, bone fragment in wall, rectal/vaginal injury, or open pelvic fracture.
D. Urethral trauma — anterior vs posterior
| Feature | Anterior (bulbar) | Posterior (membranous) |
|---|---|---|
| Mechanism | Straddle/astride injury, instrumentation | Pelvic fracture (shearing at prostatomembranous junction) |
| Signs | Blood at meatus, butterfly perineal haematoma | Blood at meatus, high-riding/boggy prostate, distended bladder |
| Associated | Often isolated | Pelvic #, multi-trauma |
| Dx | RGU (NEVER catheterise blindly) | RGU |
| Initial Mgmt | Suprapubic catheter / catheter if partial | Suprapubic cystostomy + delayed urethroplasty |
High-yield: Blood at the external meatus = contraindication to catheterisation → do RGU first. Posterior urethral injury initial step = suprapubic catheter, definitive = delayed (≈3 months) anastomotic urethroplasty. Long-term sequelae triad: stricture, incontinence, impotence (erectile dysfunction).
Goldman classification of posterior urethral injury (Type I–V) and straddle = bulbar are classic exam labels.
Key differentials
- Causes of poor urinary stream / LUTS: BPH (older, on PR enlarged smooth prostate), bladder neck stenosis, detrusor underactivity, neurogenic bladder, urethral stricture (younger, post-infective/instrumentation, plateau uroflow).
- Blood at meatus: urethral injury vs simply traumatic catheterisation vs distal stone.
- Haematuria post-trauma: renal vs bladder vs urethral — localise by exam + imaging.
Recently asked / exam angle
- AAST grade for "urinary extravasation/collecting system tear" → Grade IV; "shattered kidney/hilar avulsion → Grade V" (frequently a one-line MCQ).
- Extraperitoneal bladder rupture management = conservative (catheter); intraperitoneal = surgery — direct repeat favourite.
- Investigation of choice: stricture → RGU; renal trauma → CECT with delayed films; bladder rupture → CT/retrograde cystogram with post-drain film.
- Contraindication to catheterisation = blood at meatus (do RGU) — image-based clinical vignette.
- Commonest site of stricture = bulbar; commonest cause now = iatrogenic.
- Graft of choice for substitution urethroplasty = buccal mucosa.
- Commonest site of posterior urethral rupture = prostatomembranous junction with pelvic fracture.
- Applied anatomy: which fascial planes confine the "butterfly" haematoma (Colles' fascia, Buck's fascia, Scarpa's fascia continuity).
- Watering-can perineum — eponym for neglected stricture with multiple fistulae.
Rapid revision
- Commonest stricture site = bulbar; commonest cause today = iatrogenic (historically gonococcal).
- RGU = distal end, MCU = proximal end; combine for tight post-traumatic gaps.
- Uroflow in stricture = plateau/box-shaped curve.
- Short single bulbar stricture → DVIU; recurrent/long → urethroplasty (buccal mucosa graft).
- Watering-can perineum = multiple perineal fistulae from chronic stricture.
- Kidney = most commonly injured urological organ in blunt trauma; CECT with delayed phase is IOC.
- AAST: Grade IV = collecting-system tear/urine leak; Grade V = shattered kidney/hilar avulsion.
- Renal trauma: surgery only if haemodynamically unstable / expanding pulsatile haematoma; persistent leak → DJ stent, bleeding → angioembolisation.
- Extraperitoneal bladder rupture → catheter drainage; intraperitoneal → surgical repair. Cystogram needs a post-drainage film.
- Blood at meatus = do RGU, never blind catheterise.
- Anterior urethral injury = straddle (bulbar) + butterfly perineal haematoma; posterior = pelvic fracture (membranous) + high-riding prostate.
- Posterior urethral injury triad of late sequelae = stricture, incontinence, impotence; initial Rx = suprapubic catheter, definitive = delayed anastomotic urethroplasty.