Etiology of Urethral Strictures
Urethral strictures are most commonly caused by iatrogenic factors (particularly transurethral surgery and urethral catheterization) and idiopathic causes in developed countries, while trauma predominates in developing nations. 1
Primary Etiologic Categories
In Men
According to the 2023 AUA guidelines, the major causes include 1:
Iatrogenic causes (most common in developed countries):
- Transurethral surgery - the single most common iatrogenic etiology among those with identifiable causes
- Urethral catheterization - particularly prolonged or traumatic catheterization
- Hypospadias surgery - late failures
- Prostate cancer treatment (radiation, prostatectomy)
- Cystoscopy and other urethral instrumentation
Idiopathic:
- Accounts for a substantial proportion of cases where no obvious cause can be identified despite thorough history
- More common in the 40-59 year age group 2
Traumatic:
- Pelvic fracture urethral injuries (most common traumatic cause)
- Blunt perineal trauma
- Straddle injuries
- More prevalent in developing countries due to higher rates of road traffic injuries 3
Inflammatory/Infectious:
- Lichen sclerosus (LS) - tends to produce longer strictures, more commonly affects the penile urethra, and carries higher association with urethral cancer 1
- Recurrent urinary tract infections
- Sexually transmitted infections (historically more common, now less frequent)
In Women
Women have distinctly different etiologic patterns 1:
Iatrogenic (most common):
- Painful or traumatic catheterization
- Multiple urethral dilations leading to fibrosis from bleeding and extravasation
- Pelvic surgery
Other causes:
- Blunt pelvic trauma
- Obstetric complications (particularly cephalopelvic disproportion)
- Malignancy
- Radiation therapy
- Urethral and/or vaginal atrophy
- Recurrent infections
- Skin diseases (lichen planus, lichen sclerosus)
Age-Specific Patterns
The etiology varies significantly by patient age 1, 2:
Younger patients (<45 years):
- Idiopathic causes
- Hypospadias surgery complications
- Pelvic fracture/trauma
Older patients (>45 years):
- Transurethral resection
- Idiopathic causes
- Urethral catheterization
Patients >60 years:
- Iatrogenic causes account for 68% of cases 2
Location-Specific Patterns
Penile urethra:
- Hypospadias surgery
- Idiopathic strictures
- Urethral catheterization
- Lichen sclerosus
Bulbar urethra (most common site overall - 52%):
- Idiopathic strictures (most prevalent)
- Transurethral resection
- Trauma
Multifocal/panurethral strictures:
- Urethral catheterization (main cause)
- Lichen sclerosus
Posterior urethra:
- Pelvic fracture (main cause)
- Prostate surgery/radiation
Contemporary Epidemiologic Data
Recent research confirms that iatrogenic causes account for approximately 43-48% of all urethral strictures in developed countries 4, 2, 5. A 2025 study found urethral catheterization alone responsible for 48.6% of all strictures 5. This represents a significant shift from historical patterns where infectious causes (particularly gonorrhea) were more prevalent.
Critical Clinical Implications
Prevention strategies should focus on:
- Avoiding unnecessary urethral catheterization
- Using careful technique during catheterization (smallest appropriate catheter size, adequate lubrication)
- Minimizing repeated urethral instrumentation
- Proper training of healthcare professionals in urethral manipulation 2, 5
Common pitfall: Assuming all strictures in young men are traumatic - idiopathic and iatrogenic causes are actually more common in this age group in developed countries 1.
Important caveat: In approximately one-third of cases, no obvious cause can be identified despite thorough investigation, emphasizing the multifactorial and incompletely understood nature of stricture pathophysiology 4.