Procedure A cyst is a fluid-filled mass. Although most cysts do not require drainage, some cysts are cosmetically troublesome for patients, or present with an atypical appearance. After a cyst is identified using ultrasound, the skin is prepped with betadyne. Local anesthetic is placed in the skin and subcutaneous tissues. A needle is placed through the skin into the cyst, and the fluid is removed. If necessary, the fluid can be sent to the laboratory for additional analysis. Despite being drained, many cysts may re-accumulate fluid after time. This is not abnormal.