The flexible bulb has a plug that c

The flexible bulb has a plug that can be opened to pour off collected fluid. Each time fluid is removed, the patient, caregiver or healthcare provider squeezes the air out of the bulb and replaces the plug before releasing the bulb. The resulting vacuum creates suction in the drainage tubing, which gradually draws fluid from the surgical site into the bulb. The bulb may be repeatedly opened to remove the collected fluid and squeezed again to restore suction. It is best to empty drains before they are more than half full to avoid the discomfort of the weight of the drain pulling on the internal tubing.