In a typical adult without urethral stricture, infection, or anatomic abnormalities, is expulsion of a renal calculus through the urethra less painful than its passage from the kidney into the ureter or from the ureter into the bladder?

Pain During Stone Passage: Location-Specific Analysis

Passage of a kidney stone from the bladder through the urethra is generally less painful than passage from the kidney into the ureter or through the ureter itself. The ureter has three anatomic narrowing points where stones cause maximal obstruction and pain, whereas the urethra is wider and more distensible, particularly in males without stricture disease.

Pain Mechanisms by Anatomic Location

Kidney to Ureter (Ureteropelvic Junction)

• The ureteropelvic junction (UPJ) represents the first major anatomic narrowing where stones cause acute obstruction and severe renal colic 1
• Stones at the UPJ produce maximal distension of the renal pelvis and capsule, generating intense visceral pain that often requires urgent intervention 1
• This location accounts for approximately 22 of 345 total urinary calculi in observational studies, representing a critical pain point 2

Through the Ureter

• The ureter has three physiologic narrowing points: the UPJ, where the ureter crosses the iliac vessels (mid-ureter), and the vesicoureteric junction (VUJ) 2
• Ureteral stones cause severe colicky pain due to smooth muscle spasm, obstruction, and distension proximal to the stone 1
• Distal ureteral stones (68-83% spontaneous passage rate) still produce significant pain requiring analgesics, though passage rates are higher than proximal stones 1
• The VUJ is the second most common site of ureteral stone impaction (33 of 345 stones) and produces severe pain despite being close to the bladder 2

Bladder to Urethra

• Once a stone enters the bladder, the acute obstruction and ureteral spasm resolve, dramatically reducing pain 1
• The male urethra averages 20 cm in length but is significantly wider and more distensible than the ureter, particularly in patients without stricture disease 3, 4
• Urethral stones are uncommon (only 6 of 345 total urinary calculi) and typically present with retention rather than severe pain 2
• In a series of 36 patients with urethral calculi, only 8 patients (22%) presented with acute retention, and most stones could be manipulated endoscopically without major complications 5

Clinical Evidence Supporting Lower Urethral Pain

Anatomic Considerations

• The ureter diameter ranges from 2-4 mm at its narrowest points, whereas the male urethra ranges from 6-10 mm in the pendulous portion 3, 4
• Stones that successfully traverse the entire ureter (having passed through three critical narrowing points) are typically small enough to pass through the urethra with minimal resistance 6
• Stones ≤5 mm pass spontaneously through the distal ureter in 89% of cases, and once in the bladder, urethral passage is typically straightforward 1, 7

Pain Management Requirements

• Patients with ureteral stones require NSAIDs (diclofenac, ibuprofen) as first-line pain management and often need opioid analgesics 8
• Medical expulsive therapy with tamsulosin reduces pain episodes and analgesic requirements specifically for ureteral stones 5-10 mm, indicating significant baseline pain 7
• No comparable pain management protocols exist for bladder-to-urethral passage, as this phase rarely produces severe pain requiring intervention 5

Time Course of Pain

• Stones 2-4 mm take an average of 12.2 days to pass through the ureter, with 95% passing by 40 days, during which patients experience recurrent colic 6
• Stones 4-6 mm take an average of 22.1 days to pass, with prolonged pain episodes throughout the ureteral transit 6
• Once stones reach the bladder, passage through the urethra typically occurs within hours to days without the prolonged pain characteristic of ureteral transit 5, 6

Common Pitfalls and Caveats

• Do not assume painless urethral passage in patients with urethral stricture disease (prevalence 0.9% in men), as strictures can cause significant obstruction and pain 3, 4
• Posterior urethral strictures were present in 42% of patients with urethral calculi and required visual internal urethrotomy before stone manipulation 5
• Female patients have a shorter urethra (3-4 cm) and typically experience even less pain during urethral stone passage than males 3
• Infection changes the clinical picture entirely—infected obstructing stones at any level constitute a urologic emergency requiring immediate decompression regardless of pain level 1