A simple kidney cyst is a round pouch of smooth, thin-walled tissue or a closed pocket that is usually filled with fluid. One or more may form within the kidneys. Simple cysts are the most common type of kidney cyst. They are not the same thing as polycystic kidney disease, which is a progressive disease that can lead to kidney failure. Simple kidney cysts most often do not cause harm.
Simple Kidney Cyst Causes
The cause of simple kidney cysts is not fully understood. However, these cysts do not appear to be inherited. Age may increase your risk because almost one-third of people over age 70 have at least one simple kidney cyst. The size of these cysts may also increase with age.
Simple Kidney Cyst Symptoms
Simple kidney cysts usually do not cause symptoms. In most cases, a doctor finds them during an ultrasound or computerized tomography (CT) scan done for another reason. However, simple kidney cysts may:
- Cause pain in your side, back, or upper abdomen if they enlarge and press on other organs
- Become infected, causing fever, chills, or other signs of infection
- Impair kidney function (rare)
Simple kidney cysts have been associated with high blood pressure, but it is unclear what the relationship is between the two.
Simple Kidney Cyst Treatment
If your cyst does not cause symptoms or complications, you do not need treatment. Your doctor may simply watch your cysts to make sure they don't cause any problems. However, if you have symptoms, you may need treatment.
You may have a procedure that involves these steps:
- A doctor punctures the cyst with a long needle inserted through the skin, using ultrasound for guidance.
- The doctor drains (aspirates) the cyst.
- Then the doctor may fill the cyst with a solution that contains alcohol. This causes the tissue to harden and lowers the chances of recurrence. Scarring down the space within the cyst is called sclerosis.
Usually, this is all that is needed to treat a simple kidney cyst. However, in some cases a cyst will return and refill with fluid.
You may need surgery under general anesthesia for a large cyst or one that returns after aspiration and sclerosis. The doctor may perform surgery with a large incision (open surgery). However, it usually involves these steps:
- A surgeon makes small incisions.
- The doctor inserts a thin, lighted viewing tube (laparoscope) and other instruments.
- Then, the doctor may drain the fluid, and remove or burn the cyst's outer wall to keep it from reforming. This is called laparoscopic cyst decortication.
- You may stay in the hospital for one or two days after surgery.