Sudden pain in the waist can be caused by the following reasons: First, blockage of arteries in the kidney. When the arteries in the kidney are blocked due to thrombosis or embolism, there can be sudden pain in the waist, often tear-like pain, which should be diagnosed and treated by examining the angiography of the kidney. Second, the rupture of kidney tumor, when the kidney tumor rupture can have sudden back pain, also can be tear-like pain, to check the kidney ultrasound, MRI, CT to diagnose and treatment. Third, kidney stones, when kidney stones travel down and get stuck in the narrowing of the ureter, there can be a sudden pain in the waist, then ultrasound, CT and urine tests of the kidney should be checked to diagnose and treat.