Urethral calculi are an uncommon type of urolithiasis, accounting for ~1% of all urinary tract stones.
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Epidemiology
They almost all occur in males 2 with two peak incidences - one in childhood and the other at 40 years 3.
Clinical presentation
Most commonly acute lower urinary tract symptoms and/or urinary retention.
Pathology
Urethral calculi are most commonly calcium oxalate (~85%) and can be either 1,2,5:
- primary: arising de novo secondary to other pathologies such as diverticula, strictures, neurogenic bladder or foreign bodies
- secondary: originate in the upper urinary tract (much more common)
Location
Most impact in the prostatic urethra although ~40% (range 30-50%) are found in the anterior urethra 2,5.
Radiographic features
Almost all (98-100%) of urethral stones are reported to be radiopaque 3 but most are small and only faintly radiopaque and up to 60% will be missed 5.
Differential diagnosis
- pelvic phlebolith
- prostatic calcification: transrectal ultrasound can be helpful for differentiation 4
- Coaptite injection 6
