DZ has commented before on newspaper articles seem to be increasingly written by sloppy lazy journalists, and published by indifferent editors.
To read the headline you'd think this was an event of clear negligence. As if the normal theatre procedures were not diligently followed, and the patient went on his way with everyone involved blissfully unaware of the problem.
If you read the article it's obvious that, in fact that was not at all what happened. The end of surgery instrument check obviously did correctly identify that an instrument was missing, and the correct procedure for finding it was followed. While the patient was still anaesthetised. There was then a clinical decision made to leave it where it was and retrieve it at a subsequent procedure.
It's highly unlikely that the patient would come to any harm as a result of this, and in reality it's a complete non story. yet another case of some hack writer trying to generate copy out of nothing.