I think In-House audit-trails are pretty sophisticated now. We can more or less tell who did what, how and when for samples that remain within our laboratory. This is particularly true for laboratories that have paperless systems and electronic audit trails.
Where laboratories in general are not so good is when samples get sent away to other laboratories outwith the local network, i.e. reference labs.
The computer systems may be different, interfacing may not be easy, the sample may go to the wrong department, it can be difficult getting the result back etc etc. The reference laboratory may not appreciate the importance or urgency of a particular sample.
Good transit auditing using professional tracking systems, good relationships and sound electronic communication between the referring and reference lab all help to reduce these problems. However at the end of the day, sending samples outwith your own laboratory network is always a leap of faith. You lose an element of control over the sample and establishing audit trails for a particular sample outwith your own laboratory can be frustrating work. In addition these are often some of the most important samples received into the laboratory.
However what you can be sure of is that the referring laboratory will generally get the blame from the requestor if something goes wrong!