What is the purpose of a filter needle?

A filter needle is specifically designed to filter out particles, such as glass shards that may be present in a vial, especially those that contain a rubber stopper. When a vial is punctured, there is a risk of small glass pieces breaking off, particularly if the vial has been dropped or mishandled. The filter in the needle helps to ensure that these unwanted particles do not enter the syringe containing the medication.

This capability is crucial for patient safety, as injecting particles could lead to severe complications, such as embolism or other adverse effects. In settings where vials are common, such as in hospitals or clinics, using a filter needle is an important practice to minimize risks associated with parenteral medication administration.

The other options do not align with the primary function of a filter needle. Injecting medication and withdrawing fluid from a vial are basic functions typically done with standard needles, while drawing blood samples requires specific types of needles that may not have filtration capabilities.