Is it possible that an 8mm long kidney stone doesn't pain and create any discomfort?

If yes, why or when?

  • 3
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    – Carey Gregory
    Commented Mar 15, 2023 at 23:07

1 Answer 1


A kidney stone (nephrolithiasis) is a calculus (stone) existing within the kidney and/or the collecting system before it enters the ureter.1 A ureteral stone (ureterolithiasis) is a calculus (stone) that has exited the kidney and exists within the ureter (the passageway between the kidney and the urinary bladder). 1,2A nephrolithiasis (stone within the kidney) is unlikely to cause pain. On the other hand, ureterolithiasis (a stone existing within the ureter) is more than likely to cause discomfort and severe pain when 8mm in size. It would be highly unusual and unlikely for a ureteral stone of 8mm not to be painful or cause discomfort. Any ureteral stone >5mm is likely to obstruct because, at that point, it is estimated to be around 11%-22% larger than the inner diameter of the ureter.3 Therefore, 8mm would more than likely be in contact with the ureteral walls, causing a pain response and obstruction. Pain response is primarily due to ureteral wall agitation, and renal capsule distention (secondary to obstruction).4


  1. Nephrolithiasis: Practice Essentials, Background, Anatomy. Published online July 13, 2022. Accessed March 18, 2023. https://emedicine.medscape.com/article/437096-overview
  2. Ureter Anatomy: Overview, Gross Anatomy, Microscopic Anatomy. Published online October 14, 2022. Accessed March 18, 2023. https://emedicine.medscape.com/article/1949127-overview
  3. Liu Y, Li M, Qiang L, Sun X, Liu S, Lu TJ. Critical size of kidney stone through ureter: A mechanical analysis. J Mech Behav Biomed Mater. 2022;135:105432. doi: 10.1016/j.jmbbm.2022.105432
  4. Kidney stones in adults: Diagnosis and acute management of suspected nephrolithiasis - UpToDate. Accessed March 18, 2023. https://www.uptodate.com/contents/kidney-stones-in-adults-diagnosis-and-acute-management-of-suspected-nephrolithiasis?search=kidney%20stone&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1
  • What does the absence of pain indicate?
    – user366312
    Commented Mar 18, 2023 at 10:30
  • @user366312 This answers that for you in the third sentence.
    – Carey Gregory
    Commented Mar 18, 2023 at 15:07

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