A system for retrieving material from a cavity in a patient may include a tube having a proximal end and a distal end, the scope configured to be inserted into the cavity, and a filter assembly disposed between the tube and a vacuum source configured to apply negative pressure through the tube to cause the material to flow through the tube from the distal end to the proximal end, the filter assembly including a filter configured to trap the material in the filter assembly, and allow liquid and gases to pass through the filter assembly.