Synopsis
Interpret stone size and ureteric location as probabilistic evidence, combine them with clinical safety and verify whether observation has achieved passage.
- Smaller and more distal ureteric stones are generally more likely to pass; quoted passage figures describe study populations rather than a guaranteed outcome for an individual.
- Observation requires controlled symptoms, no infection and no threatened renal function, together with an informed patient and a practical reassessment plan.
- NICE advises treatment within forty eight hours of diagnosis or readmission when adult ureteric-stone pain remains intolerable or the stone is unlikely to pass; this is distinct from emergency infected-obstruction drainage.
Reasoning priorities
Define stone location, dimensions and obstruction before counselling about passage.
Use the actual image or radiologist’s report to distinguish distal, middle and proximal ureteric disease. Compare multiple measurements consistently on subsequent imaging. Density, anatomy and visibility on plain imaging may also inform eventual treatment selection, but they are not substitutes for the observation safety assessment.
Worked reasoning
A forty year old has a four-millimetre stone in the distal right ureter.
- CT shows one stone with mild upstream dilation and a normal contralateral kidney. He is afebrile, renal function is at baseline and initial analgesia has controlled pain. He can drink and has transport back to hospital. The team therefore evaluates passage likelihood only after establishing that a period of observation is clinically acceptable.
- The clinician explains that small distal stones often pass and cites the limited-data EAU estimate of about 89% for distal stones below 5 mm, while making clear that it is not his personal guarantee. He chooses observation over an immediate procedure after discussing possible recurrent pain, the need for reassessment and the option to change the plan.
- At the agreed two-week individual review, he has had no further severe pain but has not recovered a stone. Because passage is uncertain and the original scan showed dilation, follow-up imaging is arranged to answer whether obstruction persists; the absence of pain is not used as the final endpoint.
- Before the imaging appointment he catches a stone and supplies it for analysis. Ultrasound then shows resolution of dilation and repeat creatinine remains at baseline. The review records concordant passage and renal recovery, cancels an unnecessary planned stone intervention and begins prevention assessment from the recovered material. The two-week review was an individual plan, not a universal guideline interval.
A stable patient has a larger or more proximal ureteric stone without infection.