<unk>  have a tendency to become occluded or clogged, resulting in retained fluid that can contribute to infection or other complications. Thus efforts must be made to maintain and assess patency when they are in use. Once a<unk> becomes clogged or occluded, it is usually removed, as it is no longer providing any benefit.
Drain 
Trocar
Transudate
Urinal 
Port 
Exudate
Injection port
Mikulicz's drain