Some causes of bloody urine not associated with abdominal pain include a bladder or kidney infection and kidney disease, according to WebMD. Other common causes include menstruation, sexual activity and trauma, explains the National Institute of Diabetes and Digestive and Kidney Diseases. In some cases, blood in the urine indicates a serious medical condition, such as cancer of the kidneys or bladder, a clotting disorder, sickle cell disease or polycystic kidney disease.
Most people with blood in their urine have no symptoms, explains the National Institute of Diabetes and Digestive and Kidney Diseases. To diagnose what's wrong, doctors typically order a urinalysis, a test in which a lab technician examines the urine under a microscope. The presence of white blood cells in the specimen is usually indicative of infection in the bladder or kidneys. If the urine contains misshapen red blood cells known as casts, this may be a sign of a underlying kidney disease, especially if the urine contains an abnormally large amount of protein. The technician also looks for cancer cells.
If the urinalysis does not show a clear cause for the bloody urine, doctors typically order a blood test to look for excess amounts of the waste products that healthy kidneys normally remove. If these are high, it may indicate kidney disease, explains WebMD. Other signs of kidney disease include weakness, swelling and high blood pressure. Symptoms of a kidney infection include fever, chills and pain in the lower back.
Other tests that help doctors diagnose the cause of bloody urine include imaging studies, such as a CT scan, an ultrasound of the kidneys and a special X-ray known as an intravenous pyelogram, states WebMD. If the cause remains unknown, doctors usually adopt a wait-and-see approach and monitor the patient every three to six months.