Towards the end of Doug Ross' (George Clooney) time on the show he did a quick detox to a kid so the mother would stop taking the kids drugs. At the beginning of the second episode that this is taking place Carrie is yelling at him as they are taking the kid upstairs.

When they get to the peds unit he starts listening to the kids heart/lungs with a stethoscope.

Cut to Carrie.

Back on Doug and he is just taking them off from around his neck.

Cut to Carrie

Back on Doug and its around his neck again.

Cut to Carrie

He's listening with the stethoscope again