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, but they do not appear to be inherited. Being male is a risk factor, however, as is age: Almost half of all people over the age of 50 have one or more simple cysts in the kidneys. The size of these cysts may also increase with age, which may double over 10 years.
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, in the rare case that 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 and may then fill the empty pouch 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.
In some cases, a cyst will return and refill with fluid. Your doctor may recommend surgery that entails general anesthesia and a large incision. During the procedure, the surgeon would insert a thin, lighted viewing tube called a laparoscope and other instruments to drain the fluid from the cyst and remove or burn its outer wall to keep it from reforming.
You may need to stay in the hospital for one or two days following the surgery.