The presence of blood clots in urine, a condition known as hematuria, can indicate a variety of other conditions and patients are advised to see a doctor to get an official diagnosis and treatment. For example, kidney stones can cause blood clots to appear in the urine, though stones in the bladder can do the same. Urinary tract issues, such as a urinary tract infection, may also cause blood clots in urine. In some cases, the cause of hematuria is not a disease but inflammation resulting from an injury such as falling or being hit in the kidney or bladder. One of the most serious causes of blood clots in urine is a tumor in the kidney or bladder.

One of the most common causes of a blood clot in the urine is stones in the kidney or bladder. Kidney stones can be difficult to pass and may cause symptoms that include painful urination, pain in the groin, nausea and vomiting. The resulting urine is often cloudy and orange, red or pink, depending on the amount of blood in it. Stones can also occur in the bladder, with symptoms that include difficulty urinating despite the urge to do so frequently, abdominal pain and bloody urine. Doctors can usually diagnose kidney and bladder stones and may recommend treatment for particularly large stones.

A urinary tract infection (UTI) is another common cause of blood clots in urine. The symptoms typically include pain in the lower back and abdomen, increased frequency of urination with a decreased amount of urine, and cloudy urine that smells bad. Patients who do not have any symptoms aside from blood in the urine may be suffering from an injury. For example, getting hit in the kidney or bladder can cause inflammation and bloody urine with no other symptoms aside from some pain in the flank or lower abdomen. Patients who suspect either an infection or injury in the urinary tract should see a doctor to ensure that the condition is not more serious than they assume.

In some cases, blood clots in urine can indicate tumors in the urinary tract's organs. For example, bladder tumors often cause pain in the abdomen and back, recurrent UTIs and bloody urine. Tumors may be benign or cancerous, so they should be checked out by a doctor. The same goes for tumors in the kidney, which could be benign and fairly harmless or indicate renal cell carcinoma, a type of kidney cancer. The symptoms of renal cell carcinoma include pain in the abdomen and back, weight loss and blood clots in the urine.