What is the root operation for fluid removal?

The root operation for fluid removal is drainage, as this term specifically refers to the process of removing fluid from a body part, such as an abscess or other cavity. In medical coding, under the ICD-10-PCS system, drainage involves the extraction of fluids that have accumulated, which can be necessary for treating infections or relieving pressure from swollen areas.

The other options pertain to different surgical operations: excision involves cutting out a piece of tissue; destruction means to eliminate or destroy tissue; and resection involves cutting out a part of an organ or structure. These terms do not accurately describe the action of fluid removal, which is why drainage is the correct choice.