During the operation field A was voided.

In: https://en.oxforddictionaries.com/definition/void

2.Discharge or drain away (water, gases, etc.) ‘the
gases are usually voided into the mechanism’ More example sentences
 
2.2 usually as adjective voided Empty or evacuate (a container or space) ‘a fully voided core assembly’ 

During the operation field A was voided.

At Oxford Dictionaries’ online site we read for void:

2. Discharge or drain away (water, gases, etc.) ‘the gases are usually voided into the mechanism’ More example sentences

2.2 usually as adjective voided Empty or evacuate (a container or space) ‘a fully voided core assembly’