Can a bladder stone cause urinary obstruction?

Can Bladder Stones Cause Urinary Obstruction?

Yes, bladder stones can cause urinary obstruction, though this is relatively uncommon in contemporary practice—they typically cause irritative lower urinary tract symptoms rather than complete obstruction, but large stones can physically block the bladder neck or urethra, leading to urinary retention.

Mechanism of Obstruction

• Bladder stones can physically obstruct the bladder outlet by lodging at the bladder neck or internal urethral meatus, particularly when they are large 1, 2
• Giant bladder stones (>100mm diameter) occupying the entire bladder lumen have been documented to cause obstructive symptoms, though irritative symptoms often predominate 2
• The stone acts as a ball-valve mechanism, intermittently blocking urinary flow during voiding attempts 1

Clinical Presentation Patterns

• Irritative symptoms are more common than obstructive symptoms: urgency, frequency, dysuria, and hematuria typically dominate the clinical picture 2, 3
• Obstructive symptoms occur but are less frequent: urinary retention, weak stream, and incomplete emptying can develop when stones are sufficiently large 2, 3
• Recurrent urinary tract infections are a hallmark finding, as bladder stones create a nidus for bacterial colonization 4, 3

Size and Obstruction Risk

• Stones weighing 465-826 grams have been reported, with diameters exceeding 110mm, yet some patients maintain voiding ability despite massive stone burden 2, 3
• The relationship between stone size and obstruction is not linear—smaller stones can cause intermittent obstruction if mobile, while larger stones may remain relatively asymptomatic until they reach critical size 1, 2
• Complete bladder outlet obstruction requiring urgent intervention is the exception rather than the rule 1

Underlying Pathophysiology Context

• Bladder stones comprise only 5% of all urinary tract stones, making them relatively uncommon 2, 3
• Traditional teaching emphasized bladder outlet obstruction (BOO) as the primary predisposing factor, but recent evidence suggests metabolic factors play a more significant role than previously recognized 5
• In patients with concomitant kidney and bladder stones, composition concordance is 70%, indicating systemic lithogenic factors rather than pure mechanical stasis 5
• Infection stones (struvite/carbonate apatite) can form even without infravesical obstruction, particularly in patients with recurrent UTIs 4, 3

Common Pitfall to Avoid

• Do not assume all bladder stones require emergent intervention for obstruction—most patients present with chronic irritative symptoms rather than acute retention 2, 3
• Physical examination may reveal a palpable suprapubic mass in cases of giant stones, which can be mistaken for bladder distension from retention 2
• Post-void residual volume measurement is essential to distinguish true obstruction from irritative symptoms—median residuals in bladder stone patients are often modest (76 mL) despite significant stone burden 5

Management Implications

• Endoscopic management via the urethral route using pneumatic lithotripsy is the preferred approach for most bladder stones, regardless of size, as it has negligible morbidity compared to open cystolithotomy 1
• Concomitant treatment of bladder outlet obstruction (if present) should be performed during the same procedure to prevent recurrence 5
• Stone composition analysis guides metabolic evaluation and prevention strategies, as bladder stone composition predicts kidney stone composition in 70% of cases 5