Kidney Stones (Obstructing & Non-Obstructing)
Kidney stones are hard mineral deposits that form in the kidneys. They vary in size, number, and composition and may remain in the kidney (non-obstructing) or move into the ureter and block urine flow (obstructing). Non-obstructing stones often cause little or no symptoms, while obstructing stones can cause severe flank pain, nausea, vomiting, or urinary problems. Imaging is essential for identifying the size, location, and impact of the stones.
What is it?
Kidney stones form when minerals and salts in the urine crystallize. Factors such as dehydration, diet, genetics, infections, and metabolic conditions can increase the likelihood of stone formation. Non-obstructing stones stay in the kidney and often cause no symptoms. Obstructing stones, however, enter the ureter and can block urine flow, causing swelling of the kidney (hydronephrosis) and significant pain.
Imaging—especially CT—helps identify the size and location of stones and whether they are causing obstruction. Ultrasound may show stones or hydronephrosis but is less sensitive for small stones. X-rays can detect stones that contain calcium but may miss others.
Important to Know
Small stones may pass on their own with hydration and medications. Larger stones or stones causing obstruction may require procedures such as lithotripsy (shockwave treatment), ureteroscopy, or surgical removal. Untreated obstruction can lead to infection or kidney damage, making early evaluation important.
Red flag symptoms include fever, chills, severe flank pain, inability to urinate, persistent vomiting, or blood in the urine. These may indicate infection or significant obstruction requiring urgent medical attention. Follow-up imaging is often recommended to assess stone passage or monitor non-obstructing stones.