Kidneys filter salts, toxins and water from blood, and this body waste is then transferred to the bladder where it is excreted as urine. Each day, the kidneys process about 200 qt. of blood, converting it into what will be about 2 qt. of urine, according to the National Kidney and Urologic Disease Information Clearinghouse. If the kidneys are prevented from cleaning the blood, kidney damage can occur and dangerous toxins can build up in the blood.
Anatomy
Kidneys are about the size of a person's fist and are shaped like a bean. The organ is made of tiny tubes that clean the blood, called nephrons. Urine is stored in a collecting area called the renal pelvis, and then passes down a long tube called the ureter that leads to the bladder.
Hydronephrosis
Urine flows out of the kidneys at an extremely low pressure. If something obstructs the urinary tract, pressure builds above the obstruction. Urine begins to back up into the renal pelvis and the tiny tubes inside the kidney, and the ensuing increase in pressure causes the kidneys to enlarge. This condition is called hydronephrosis.
Other Causes
Kidney stones are the most common cause of obstruction of the urinary tract, according to the Merck Manuals Online Medical Library, although other conditions like structural abnormalities, tumors and other disease can also restrict the flow of urine to the bladder. Kidney stones are created in the kidneys from substances in urine. Small kidney stones may pass through the urinary tract with no problems. Larger stones may become lodged in the ureter, bladder or the urethra, which is the tube that leads from the bladder to the outside.
Symptoms
The patient will usually complain of flank pain because kidneys are located near the middle of the back, just below the ribcage. Pain can be felt on either side of the spine. It may be painful to urinate, according to MayoClinic.com. Blood may be present in the urine, which may have an unpleasant smell and appear cloudy. The patient may vomit and have fever with chills.
Diagnosis
Diagnosing a blockage in the kidney begins with a physical examination. A detailed medical history will be noted, and vital signs like temperature and blood pressure will be obtained. The physician will also likely order catheterization, which drains the bladder by inserting a flexible tube into the urethra. Laboratory blood and urine tests will be ordered, as well as standard X-rays. Advanced testing like CT scans and ultrasounds may be done to help the physician visualize the kidneys.
Treatment
Treatment is usually designed around removing the obstruction. Shock waves are an effective way to break kidney stones into small pieces, which are easier to pass in the urine. Tunnel surgery refers to a procedure where a physician makes a small tunnel in the skin to the kidney, then inserts a special tool into the tunnel to enter the kidney and remove the stone. Another treatment is to insert a camera on a wire, called an ureteroscope, into the urethra, through the bladder to the ureter where the stone is located. The doctor can then break up the stone with a special attachment to the ureteroscope.
