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What is Urethral stricture and explain in detail?
A urethral stricture is a narrowing of the urethra, the tube connected to the bladder that allows the passing of urine. The narrowing reduces the flow of urine and makes it more difficult or even painful to empty the bladder.Urethral stricture is caused by injury, instrumentation, infection, and certain non-infectious forms of urethritis The condition is more common in men due to their longer urethra.

Signs and symptoms
The hallmark sign of urethral stricture is a weak urinary stream. Other symptoms include:
Splaying of the urinary stream
Urinary frequency
Urinary urgency
Straining to urinate
Pain during urination
Urinary tract infection
Prostatitis
Inability to completely empty the bladder.Some people with severe urethral strictures are completely unable to urinate. This is referred to as acute urinary retention, and is a medical emergency. Hydronephrosis and kidney failure may also occur.

Complications
Causes
Urethral strictures most commonly result from injury, urethral instrumentation, infection, non-infectious inflammatory conditions of the urethra, and after prior hypospadias surgery. Less common causes include congenital urethral strictures and those resulting from malignancy.Urethral strictures after blunt trauma can generally be divided into two sub-types;

Pelvic fracture-associated urethral disruption occurs in as many as 15% of severe pelvic fractures. These injuries are typically managed with suprapubic tube placement and delayed urethroplasty 3 months later. Early endoscopic realignment may be used in select cases instead of a suprapubic tube, but these patients should be monitored closely as vast majority of them will require urethroplasty.
Blunt trauma to the perineum compresses the bulbar urethra against the pubic symphysis, causing a "crush" injury. These patients are typically treated with suprapubic tube and delayed urethroplasty.Other specific causes of urethral stricture include:

Instrumentation (e.g., after transurethral resection of prostate, transurethral resection of bladder tumor, or endoscopic kidney surgery)
Infection (typically with Gonorrhea)
Lichen sclerosus
Surgery to address hypospadias can result in a delayed urethral stricture, even decades after the original surgery.

Diagnosis
Among ways to diagnose this condition is:

Cystoscopy
Urethrography

Treatment
Initial treatment usually involves urethral dilation (widening the tube) or urethrotomy, where the stricture is cut away with a cystoscope.

Dilation and urethrotomy
Urethral dilation and other endoscopic approaches such as direct vision internal urethrotomy (DVIU), laser urethrotomy, and self intermittent dilation are the most commonly used treatments for urethral stricture. However, these approaches are associated with low success rates and may worsen the stricture, making future attempts to surgically repair the urethra more difficult.A Cochrane review found that performing intermittent self-dilatation may confer a reduced risk of recurrent urethral stricture after endoscopic treatment, but the evidence is weak.

Urethroplasty
Urethroplasty refers to any open reconstruction of the urethra. Success rates range from 85% to 95% and depend on a variety of clinical factors, such as stricture as the cause, length, location, and caliber. Urethroplasty can be performed safely on men of all ages.In the posterior urethra, anastomotic urethroplasty (with or without preservation of bulbar arteries) is typically performed after removing scar tissue.In the bulbar urethra, the most common types of urethroplasty are anastomotic (with or without preservation of corpus spongiosum and bulbar arteries) and substitution with buccal mucosa graft, full-thickness skin graft, or split thickness skin graft. These are nearly always done in a single setting (or stage).In the penile urethra, anastomotic urethroplasties are rare because they can lead to chordee (penile curvature due to a shortened urethra). Instead, most penile urethroplasties are substitution procedures utilizing buccal mucosa graft, full-thickness skin graft, or split-thickness skin graft. These can be done in one or more settings, depending on stricture location, severity, cause and patient or surgeon preference.

Urethral stent
A permanent urethral stent was approved for use in men with bulbar urethral strictures in 1996, but was recently removed from the market.A temporary thermoexpandable urethral stent (Memotherm) is available in Europe but is not currently approved for use in the United States.

Emergency treatment
When in acute urinary retention, treatment of the urethral stricture or diversion is an emergency. Options include:

Urethral dilatation and catheter placement