Simple kidney cysts develop for unknown reasons, Mayo Clinic says. According to one theory, a cyst begins to form when the kidney surface loses firmness and eventually becomes a pouch. This pouch fills with fluid, separates from the kidney and grows into a cyst.
Simple kidney cysts rarely have any symptoms, WebMD explains. If symptoms do occur, they generally include bleeding, lowered kidney function, and pain in the back, side or upper part of the abdomen. Cysts are typically not discovered by their symptoms, but through procedures done to diagnose other conditions.
Treating a kidney cyst is generally not necessary unless the cyst presents symptoms or complications, WebMD states. The cyst does need to be monitored to ensure no complications develop. If treatment becomes necessary, it is typically performed in two steps. Using ultrasound, the physician pierces the cyst pouch with a needle entering through the skin. Next, the needle is used to drain the pouch and, if necessary, fill the empty space with an alcohol-based fluid that strengthens the pouch tissue and lowers the likelihood of another cyst forming. If a cyst returns, a more complex procedure is necessary to drain fluid from the pouch or fully eliminate the wall of the cyst so it cannot form in the area again.