The story stinks like a bucket of prawns left out in the sun. My sense is that if it is not entirely made up, it is so inaccurate that it might as well be made up.

Even if the woman was smoothed with a pillow -- unlikely in a case of assisted dying / voluntary euthanasia -- the thing with being smothered is that the pillow muffles any sound and the woman is unlikely to have been able to scream at all, let alone loudly enough to be heard in another room.

One report claims that an autopsy found that Wattiez died of asphyxiation, not because of the drugs they were supposed to use. Hmm, that's a bit worrying, but reportedly the autopsy found that multiple nurses "took turns" suffocating the woman which is ridiculous, an autopsy cannot determine how many people took part!

Having said all that, there are certainly cases of very shady, if not illegal, actions by hospitals, doctors and nurses. So I'm not ruling out a botched case of euthanasia, or even murder. But the story as reported is clearly sensationalised and very likely inaccurate.