Striktur Uretra

01Pathophysiology

Urethral stricture is defined as a fibrotic narrowing of the urethral lumen caused by scarring within the corpus spongiosum, a process termed spongiofibrosis. It is important to note that the term "stricture" technically applies only to the anterior urethra (the penile and bulbar segments), where the urethra is surrounded by the corpus spongiosum. Narrowing of the posterior urethra (the membranous and prostatic segments) is more accurately called stenosis or contracture, because the posterior urethra lacks a spongiosum layer and the scarring mechanism differs. Exam vignettes may not always respect this distinction, but understanding it helps you reason through etiology and management.

The pathological sequence begins with injury to the urethral epithelium. This can be mechanical (instrumentation, trauma), infectious (gonococcal urethritis causing deep periurethral inflammation), or inflammatory (lichen sclerosus). Once the epithelium is breached, the wound healing response activates fibroblasts within the surrounding spongy tissue. These fibroblasts deposit excess collagen, which contracts over time, progressively reducing the urethral caliber. The degree of spongiofibrosis determines stricture severity: mild fibrosis narrows the lumen; dense, circumferential fibrosis can obliterate it entirely.

This pathophysiology directly explains the clinical picture. As the lumen narrows, urinary flow becomes obstructed. The detrusor muscle initially compensates through hypertrophy, producing the sensation of straining. Over time, decompensation occurs, leading to elevated post-void residual volume, overflow incontinence, and eventually bilateral hydroureteronephrosis with renal impairment if the obstruction is left untreated. Urinary stasis behind the stricture also predisposes to recurrent urinary tract infections and bladder stone formation, both of which are classic secondary presentations in exam vignettes.

In the setting of pelvic fracture urethral injury (PFUI), the mechanism is different. The membranous urethra is sheared at the prostatomembranous junction by the displaced bony fragments. This produces a distraction defect rather than a true spongiofibrotic stricture. The gap fills with scar tissue, and the resulting obliterative stenosis is managed differently from anterior strictures.

02Classification and Clinical Manifestation

By Anatomical Location

By Etiology

By Severity

03Diagnostic Workup

When a vignette presents a young or middle-aged male with progressive obstructive voiding symptoms and a relevant risk factor (prior catheterization, straddle injury, history of urethritis), urethral stricture should be high on your differential.

The best initial step in the office setting is uroflowmetry, a noninvasive test where the patient voids into a flow sensor. An obstructive pattern shows a maximum flow rate ($Q_{max}Q\_\{max\}$) below 15 mL/s with a characteristic prolonged, flat, plateau-shaped curve, as opposed to the bell-shaped curve of normal voiding. This is often paired with a post-void residual measurement via bladder ultrasound. These tests screen for obstruction but do not localize or characterize the stricture.

The next step and the cornerstone of diagnosis is the retrograde urethrogram (RUG). A catheter tip is placed at the urethral meatus, contrast is injected, and fluoroscopic images are obtained. The RUG demonstrates the location, length, and degree of narrowing of the anterior urethra. If posterior urethral involvement is suspected, a voiding cystourethrogram (VCUG) is performed simultaneously: the bladder is filled with contrast (via suprapubic catheter if one is present), and imaging is obtained during voiding to visualize the proximal stricture margin. The combination of RUG and VCUG gives a complete anatomical map of the stricture, which is essential for surgical planning.

Cystourethroscopy serves as the most accurate confirmatory tool. It allows direct visualization of the stricture, assessment of the mucosal surface, and evaluation of the urethral lumen proximal and distal to the narrowing. In practice, it is often performed at the same time as a planned intervention (dilation or urethrotomy).

For exam purposes, remember this sequence: uroflowmetry (screen) then RUG (characterize) then cystourethroscopy (confirm and potentially treat).

An important caveat: in a patient presenting with acute urinary retention and suspected stricture, do not force a urethral catheter. Blind catheterization risks creating a false passage. The correct next step is suprapubic cystostomy to decompress the bladder, followed by elective RUG once the patient is stable.

04Management and Treatment

Acute Stabilization. When a patient presents with urinary retention and a known or suspected stricture, the immediate priority is bladder decompression. The critical teaching point is that a suprapubic cystostomy is the appropriate intervention, not a urethral catheter. Attempting to pass a catheter through a tight stricture can cause a false passage, urethral perforation, or significant bleeding. If a catheter is already in place and draining, it should not be removed until definitive imaging and planning are complete.

First-line Endoscopic Management. For a short stricture presenting for the first time, the standard initial approach is either urethral dilation (using progressive dilators or a balloon catheter) or direct vision internal urethrotomy (DVIU), in which the stricture is incised under cystoscopic guidance using a cold knife (the Sachse technique). The incision is typically made at the 12 o'clock position to avoid the ventrally located corpus spongiosum and its blood supply. After the procedure, a urethral catheter is left in place for several days to allow re-epithelialization.

The important exam pearl here is that while DVIU and dilation are simple and minimally invasive, their recurrence rates are high, approaching 50-60% within 2 years. Repeating a failed DVIU does not improve outcomes; each subsequent attempt adds more scar tissue. The guideline-supported principle is: if a stricture recurs after one DVIU or dilation, the next step is urethroplasty, not another endoscopic procedure.

Definitive Surgical Management: Urethroplasty. This is the gold standard for durable stricture repair, with success rates exceeding 90% in experienced hands. The technique depends on stricture length and location:

For short bulbar strictures (< 2 cm), the preferred approach is excision and primary anastomosis (EPA). The scarred segment is completely excised, the spatulated healthy urethral ends are mobilized, and a tension-free end-to-end anastomosis is performed. This yields the highest long-term patency rates.

For longer strictures (> 2 cm) or penile strictures (where excision would shorten the urethra unacceptably), a substitution urethroplasty is performed using a buccal mucosa graft (BMG). The graft is harvested from the inner cheek, which provides a robust, hair-free, wet epithelial surface that integrates well with the urethral bed. The graft can be placed as a dorsal onlay (Barbagli technique) or ventral onlay, depending on surgeon preference and stricture characteristics.

For very long or panurethral strictures, a staged approach is used. In the first stage, the urethra is opened along its ventral surface and the buccal mucosa graft is laid into the urethral plate and allowed to mature. After 6 months, the second stage tubularizes the grafted plate into a neourethra.

Posterior Urethral Disruption. Following pelvic fracture urethral injury, acute management involves suprapubic catheter placement only. Primary realignment may be attempted but carries risks of incontinence and erectile dysfunction. The definitive repair is a delayed posterior urethroplasty performed 3 to 6 months after injury, allowing the pelvic hematoma to resolve and the scar to mature. The procedure involves a perineal approach, excision of the intervening scar tissue, and a tension-free bulboprostatic anastomosis.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common way students lose points on urethral stricture questions is by confusing the management of anterior versus posterior urethral injury. A straddle injury (falling onto a bicycle crossbar or fence) damages the bulbar urethra and presents with perineal hematoma ("butterfly hematoma") and blood at the meatus, but the prostate is in its normal position on rectal exam. A pelvic fracture injury disrupts the posterior (membranous) urethra and classically presents with a high-riding prostate, blood at the meatus, and inability to void. The acute management of posterior urethral injury is suprapubic catheter placement only, with definitive repair delayed by months. Students who select "immediate surgical repair" or "pass a urethral catheter" for a pelvic fracture urethral injury scenario will get the question wrong.

A second common trap involves the recurrent stricture. When a vignette describes a patient whose symptoms returned after a prior DVIU or dilation, the answer is urethroplasty, not a repeat endoscopic procedure. Test-writers use this to assess whether you understand that endoscopic treatment is a temporizing measure with diminishing returns, and that definitive open repair is the appropriate escalation.

Third, remember that lichen sclerosus (BXO) is a testable cause of meatal and penile stricture. The vignette will describe whitish, atrophic changes on the glans and foreskin with progressive meatal narrowing. The key management pearl is that genital skin flaps must not be used for reconstruction in BXO patients, because the disease affects genital skin and will cause re-stricturing. Buccal mucosa is the graft of choice because it is resistant to BXO.

Finally, when a question stem describes a male patient with recurrent UTIs or epididymitis that keeps coming back despite appropriate antibiotic treatment, consider urethral stricture as the underlying cause. The stricture creates urinary stasis that predisposes to infection, and no amount of antibiotics will solve the problem without addressing the anatomical obstruction. The "next best step" in such a vignette is imaging with a retrograde urethrogram, not another course of antibiotics.

The core competency being tested across all urethral stricture questions is your ability to recognize obstructive voiding in the correct clinical context, select the right diagnostic study (RUG, not CT or MRI), and match the treatment to the stricture characteristics (length, location, recurrence, etiology).