Will my stone pass on its own? Size, location and timing

One night the pain started in your flank, an ultrasound or CT has said you have a stone, and now the most important question is whether it will go by itself or need an operation. The honest, short answer is this: many small stones pass on their own, but “small” and “many” have specific numbers. This article gives those numbers from its sources.

What is the chance of passing?

For newly diagnosed ureteral stones with no reason to remove them, the EAU guideline recommends “regular follow-up” first and says this is feasible for an informed patient who does not develop complications. The data in the same guideline report the chance of spontaneous passage as about 75 percent for stones under 5 mm and about 62 percent for stones of 5 mm and larger. Location matters too: stones under 5 mm passed in about 89 percent of cases near the bladder and about 71 percent in the upper ureter.

Read two points along with these numbers. First, these are group averages, not a prediction for one person. Second, the label “small” is not clearly defined in the guideline; the size categories in the data are under 5, 5 to 10, 10 to 20 and over 20 mm. A larger stone has a lower chance of passing, and in practice your doctor judges your stone from your own imaging.

How long does it take?

The NHS says passing small stones may be painful and take a few weeks. During this time its advice is to drink plenty of fluids, and you may be given painkillers, anti-sickness medicine or a medicine to help the stone pass. The NHS and NIDDK both say that if the doctor asks you to keep a stone you have passed, keep it for testing so its type can be found.

Medicine to help the stone pass

For lower ureteral stones between 5 and 10 mm, the EAU lists a group of medicines called alpha-blockers as one option and states that this use is outside the drug’s official label. The important point is that this is an option, not a guarantee, and the name and amount of the medicine are set by your doctor. Do not use leftover medicine or someone else’s prescription.

In the Cochrane review (2020), which examined 40 trials with 4,793 people, alpha-blockers after lithotripsy may help fragments pass better: the clearance rate rose from 69.3 percent in the control group to about 80.4 percent. The authors rate the certainty of this evidence as “low” and say the true effect may differ a lot. So it has been judged neither useless nor a miracle.

How is the pain controlled?

The EAU writes that in a colic attack, a group of anti-inflammatory painkillers is the first choice, as long as heart risk and the drug’s side effects allow, and stronger painkillers are the second choice. The name and amount differ from person to person, so get painkillers from your doctor and do not decide based on someone else’s medicine or your own past. If the pain does not settle with any painkiller, that in itself is a reason to seek help urgently.

When is waiting not right?

Waiting is reasonable for a small, uncomplicated stone, but not in these cases. The EAU lists these among the reasons for active removal of a ureteral stone: a low chance of spontaneous passage, pain that does not settle even with appropriate painkillers, persistent blockage, and kidney failure (including blockage of both sides or a single kidney). For a blocking stone with infection, the EAU says the urinary tract must be drained urgently and definitive treatment done after the infection settles. The NHS considers severe pain, or fever and chills, a reason to get help urgently.

In practice, these do not wait for the next appointment:

• Flank pain with fever, chills or feeling unwell.
• Having a single kidney and pain.
• Pain that does not settle with painkillers.
• Persistent vomiting that stops you drinking (NIDDK says you may need a drip).
• Urine stops or becomes very scanty.

The full list is in urgent signs. If a stone is still inside the kidney and causing no symptoms, the EAU says a growing kidney stone larger than 5 mm is a reason for intervention, and this is separate from a ureteral stone.

What should we do while waiting?

The EAU speaks of “periodic follow-up,” which means waiting is not simply being left alone; it is checked again with imaging or an examination. Increase fluids as the NHS advises (2.5 to 3 litres a day for adults, unless kidney or heart disease calls for a different amount) and watch the colour of your urine. Note the warning signs. If the pain has gone but you have not seen a stone, do not drop the follow-up: no pain does not mean the stone has gone, and RUH writes that pressure behind a blockage harms kidney function over a period of weeks. Ask your doctor when the follow-up imaging should be. After the stone passes, preventing the next one is covered in the prevention guide. If another procedure is needed, read the before a procedure guide.

A reminder

This article is for general information. Whether your stone is watched or removed is decided by your imaging, your overall health and your urologist’s opinion.