Two patients were forced to wait more than 12 hours on trolleys in A&E.
The two incidents were highlighted in the monthly report by Calderdale and Huddersfield hospital trust.
The report says the lengthy waits – a breach of the hospitals’ zero tolerance policy – occurred in October at Calderdale Royal Hospital.
The report says the transgressions were because there was “significant pressure” on medical beds across the trust but particularly for CRH.
It also says that the beds that were available were “inappropriate”.
The trust’s director of operations, Mark Partington, said: “This is very rare but unacceptable and we are looking at the causes on these particular cases to see if they could have been avoided.
“While the term ‘trolley’ is used I would like to reassure our patients that this is a fully-staffed bed – with wheels – in a private, curtained cubicle in A&E where patients are cared for pending a move into the hospital for further treatment.
“While we keep the time on them to a minimum there are occasions when it takes us longer to admit a patient”.