If you have a cyst in your breast that's bothering you, your doctor may refer you for an ultrasound-guided cyst aspiration. This is a simple, brief procedure to drain fluid from the cyst. It's performed by a radiologist, using ultrasound images to guide a small needle into the cyst and remove the fluid. Generally, once the fluid is gone, so is the discomfort. If your doctor suspects an infection, the fluid may be sent to a lab to check for the presence of bacteria.