A kidney stone is a hard deposit of minerals, most often calcium oxalate, that forms in the kidney and can move into the ureter. When it blocks the flow of urine it causes sudden, severe pain that comes in waves.
Key symptoms
- Sudden severe flank pain that comes in waves
- Pain that spreads to the lower belly, groin or testicle
- Nausea and vomiting
- Blood in the urine; urgency or burning when the stone is low
- Restless, cannot find a comfortable position
What you find on exam
- Writhing in pain, unlike peritonitis where patients lie still
- Tenderness at the costovertebral angle
- Soft abdomen without peritoneal signs
- Temperature and vital signs to look for infection or sepsis
Tests
- Urinalysis: blood; check for signs of infection
- Kidney function, electrolytes, blood count; pregnancy test when relevant
- Low-dose CT without contrast is the standard; ultrasound in pregnancy and children
- Strain the urine and analyze the stone
Treatment basics
- Pain relief: NSAIDs such as ketorolac first, opioids if needed
- Antiemetics and fluids if vomiting
- Tamsulosin can help stones of 5 to 10 mm pass
- Urology for large stones, infection, failure to pass or a single kidney
- Prevention: drink enough to make about 2.5 L of urine a day; diet based on stone type
Red flags
- Fever with a blocking stone: an emergency that needs urgent drainage
- Low urine output or rising creatinine, especially with one kidney
- Older patient with flank pain: rule out an abdominal aortic aneurysm
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.