"I think, in the end, the process has worked," Tew told Radio Sport's Martin Devlin this morning. "Patrick and his people spent some time trying to determine what had happened, before they requested the 'B' sample - that's taken up the majority of the time.
"At the end of the day, that's the safety net, it's worked and we're delighted."
But Tew regretted that considerable personal and organizational angst could have been avoided, if details had remained private.
"I know because I needed to know and the number of people that needed to know around this matter was kept to a bare minimum. Unfortunately, it was leaked on the weekend.
"If we had managed to keep this quiet, as was the athlete's right, until yesterday, then no-one would have known that Patrick had had an 'A' sample test as an abnormality.
"In the end, there's a reputational damage for him, and also for the All Blacks and our organisation that was unnecessary, which is why there are strict confidentiality regulations are in place.
Tew was disappointed that information had become public and admitted the process had let Tuipulotu down.
"Somehow, the story had got into the media and we had all that publicity, which in the end was unnecessary. I come back to the fact that reason why the regulations call for confidentiality until such time as the hearing has been held is evidenced by this particular case.
"In the end, the information was out there, Patrick and we, with the help of the [New Zealand Rugby Players Association] fronted that for a period of time until the 'B' sample came back."
Tew did not hold out much hope that NZR could find the leak: "Journalists are not normally particularly excited about giving up their sources."
He explained that NZR carries out additional drug testing on its players to ensure they are not taking banned substances, hence the surprise at Tuipolutu's positive "A" result.
"I think New Zealanders generally can be very proud of our record in this area. There will always be, from time to time, issues that we need to deal with - I think that's accepted - but actually New Zealand has a very good reputation in this area and one we can be proud of."