Producers made the decision following the strong viewer response to the plot, but assured fans that the changes did not weaken the overall story.
The spokeswoman told the Daily Star Sunday: "We can assure you that no complete scenes were cut from this episode. Given the audience response to this storyline, we felt on this occasion that it was appropriate to respond and make some changes.
"The vast majority of material remains intact and we don't believe that those trims we have made will weaken or detract from the overall storyline for viewers."
An insider added: "The scenes showing the little white coffin were a bit much. A lot of people who had already seen the episode felt it was going a little too far. So all the scenes which showed Kat clutching the coffin were left on the cutting room floor.
"After all the controversy that this storyline has caused, the last thing anyone at the BBC wanted was to make the situation even worse. The corporation's top chiefs got involved and ordered the changes. No scenes were reshot - they were just tweaked slightly."