Ureterolithiasis is a kidney stone that has moved from the kidney into the ureter, the narrow tube that carries urine from the kidney to the bladder. The stone itself typically forms in the kidney, but the condition gets its name once the stone migrates into the ureter, where it can cause obstruction, intense pain, and potential complications. It affects millions of people worldwide and is one of the most common reasons for emergency urological care.
How Stones Form and Where They Get Stuck
Kidney stones develop when minerals in the urine crystallize and clump together, usually because the urine is too concentrated or contains too much of certain substances like calcium or oxalate. While a stone sits in the kidney, it may cause no symptoms at all. The trouble starts when it drops into the ureter.
The ureter is only about 3 to 4 millimeters wide in its narrowest sections, so even a small stone can block urine flow. There are three spots where stones are most likely to get stuck: where the ureter connects to the kidney (the top), where it crosses over the pelvic bone and makes a sharp turn, and where it enters the bladder at an oblique angle. A stone lodged at any of these points can block urine drainage, causing the kidney to swell with backed-up fluid, a condition called hydronephrosis.
What the Pain Feels Like
The hallmark symptom is renal colic: sudden, severe pain in the flank or lower back that comes in waves. The pain typically radiates downward toward the groin or inner thigh as the stone moves through the ureter. Unlike a constant ache, renal colic is intermittent. It intensifies as the ureter spasms around the stone, then eases when the spasm relaxes, then surges again. Many people describe it as the worst pain they’ve ever experienced.
Nausea and vomiting are common because the nerves supplying the kidney and gut are closely linked. Blood in the urine occurs frequently as the stone scrapes the ureter’s lining. You may also feel a persistent urge to urinate, especially as the stone nears the bladder. Fever and chills alongside stone symptoms are a red flag, as they suggest an infection behind the obstruction, which requires urgent medical attention.
How It’s Diagnosed
A non-contrast CT scan of the abdomen and pelvis is the gold standard for diagnosing ureteral stones. Both the American Urological Association and the American College of Radiology recommend it as the first-line imaging test when a stone is suspected. CT picks up stones with roughly 95% sensitivity and 98% specificity, meaning it rarely misses a stone and rarely mistakes something else for one. It also reveals the stone’s size, exact location, and whether the kidney is swelling from backed-up urine.
Ultrasound is the preferred alternative for pregnant women, children under 14, and situations where avoiding radiation matters. It costs less and uses no radiation, though it’s less accurate than CT. When ultrasound results are unclear, CT is typically used to confirm the diagnosis. A urine sample will usually show microscopic blood, and blood tests can check kidney function and flag infection.
Chances of Passing a Stone on Your Own
Stone size is the single biggest predictor of whether you’ll pass it without a procedure. A large study tracking spontaneous passage rates over 20 weeks found clear cutoffs:
- 3 mm or smaller: 98% pass on their own
- 4 mm: 81% pass
- 5 mm: 65% pass
- 6 mm: 33% pass
- 6.5 mm or larger: only 9% pass
For stones with a reasonable chance of passing, doctors typically recommend watchful waiting with pain control and hydration. Medications that relax the smooth muscle of the ureter (alpha blockers) can help the stone move along more quickly, particularly for stones in the lower ureter between 4 and 7 mm. These medications widen the ureter slightly and reduce spasms, which both eases pain and improves the odds of passage. US and European guidelines recommend this approach, and it’s supported by multiple large clinical trials.
When a Procedure Is Needed
Between one-fifth and one-third of patients with ureteral stones ultimately need a procedure. Intervention is generally necessary when the stone is too large to pass, pain can’t be controlled, kidney function is declining, or infection develops behind the blockage. Two main options exist.
Shockwave lithotripsy uses focused sound waves delivered from outside the body to break the stone into smaller fragments that can pass naturally. You lie on a table while a machine generates shockwaves aimed at the stone using X-ray or ultrasound guidance. It’s typically done as an outpatient procedure without general anesthesia, and it costs less overall. The trade-off is that it’s less effective in a single session. In a large randomized trial, about 22% of patients who had shockwave lithotripsy needed additional treatment afterward.
Ureteroscopy involves threading a thin, flexible scope through the bladder and up into the ureter to directly visualize and fragment the stone, often with a laser. It’s more invasive, requires general anesthesia, and means spending more time in the hospital (usually still same-day discharge). But it’s more effective per session: only about 10% of patients needed further treatment in the same trial. For larger or harder stones, ureteroscopy is generally the better option.
Complications to Watch For
Most ureteral stones resolve without lasting harm, but a stone that stays lodged can cause problems. Prolonged obstruction leads to hydronephrosis, where the kidney swells with urine it can’t drain. If untreated, this pressure damages the kidney over time. The more urgent danger is infection developing behind a blocked ureter. When bacteria multiply in urine that can’t drain, the infection can spread to the bloodstream. Warning signs include fever above 100.5°F (38°C), chills, fatigue, cloudy urine, or feeling suddenly much sicker. This situation requires emergency drainage of the kidney, not just antibiotics.
Recurrence and Prevention
Kidney stones tend to come back. Recurrence rates run about 11% at 2 years, 20% at 5 years, 31% at 10 years, and 39% at 15 years. That means roughly one in three people who’ve had a stone will have another within a decade, which makes prevention genuinely worth the effort.
Fluid intake is the single most effective preventive measure. The goal is to produce enough dilute urine that minerals can’t easily crystallize. The standard recommendation is six to eight 8-ounce glasses of water daily, though people with a history of stones often benefit from more. Your urine should be pale yellow to nearly clear.
Dietary changes depend partly on what type of stone you had, but some guidelines apply broadly. Keeping sodium under 2,300 mg per day (about one teaspoon of table salt) helps reduce calcium in the urine. If you’ve had calcium oxalate stones, the most common type, limiting high-oxalate foods like spinach, rhubarb, nuts, peanuts, and wheat bran can help. Reducing animal protein, including red meat, poultry, fish, and eggs, lowers uric acid in the urine. Contrary to what many people assume, you generally don’t need to avoid calcium in your diet. Dietary calcium actually binds oxalate in the gut and prevents it from reaching the kidneys.