To think MIL should know DH is in hospital having serious tests, even though she's on holiday

Why worry an elderly (?) lady over what may turn out to be something and nothing? On a need to know basis, she doesn't need to know.
Not to mention that people in general are far too quick to broadcast their ailments, and sometimes it's better to preserve some privacy.
Further down the line, depending on what transpires, there may be a need to talk to her. But, OP, your husband's view is the only one that matter here - let him decide.

YABU.

If your husband doesn't want his mother contacted, then I think you must respect that. I think it would be unreasonable to contact her while she's away and it's less than a week before she comes back. I would be very angry if my husband had ever contacted my mum if it had been me in hospital when she was on holiday.

I had the similar happen to me earlier this year. I was in hospital, awaiting unexpected urgent open heart surgery which I might not have survived.

The slight difference to your scenario is that I'm single and NC with my only sibling. I do have a close relationship with my cousin who was really supportive.

My parents were away on holiday I didn't tell them. There was nothing they could have done and I knew the next few months would be difficult for them; whether I was alive or dead so felt they should enjoy their break.

Selfishly, I didn't want to have to deal with their emotions about the situation before I'd got my own head round it either.

It's not up to her to tell especially when her husband has stated clearly he doesn't want her to know.

I would tell and I would expect to be told.

You said that your DH just doesn't want to make a fuss but otherwise wants his DM there.
I think you can reassure him that he isn't making a fuss and as his mother she would want to know so she can make her own plans or even just research flights home in case they are needed. If he suddenly dies and she didn't even know anything was amiss, she will be devastated that the whole family kept it from her. If he wants his mum there he can be reassured that he should not hesitate to tell her

I am so sorry you are going through this

If he could die imminently if it's what they are testing him for I would tell her. I would try talk him around first though. But how likely is it that it is worst case scenario? If he's in 5 days already and they haven't said yet would that not indicate they are still unsure?

I'm very sorry to hear you are in this situation OP 😞

For me I would follow my DH's lead

His decision is for selfless reasons - not disrupt his mother’s holiday when it may not be necessary, but most mothers would want to know. It will be devastating for her if it is bad news and she can’t get there in time, so I think if it was me I would tell her. I sincerely hope it isn’t and feel sorry for what you are all going through OP.

I'm hoping everything turns out ok but if you were my friend I would 100 pc want you to drop your kids with me so you were free to go to the hospital (for as long as you need).
I would want to know as a parent if my adult child was potentially gravely ill so I totally understand how you feel. I'm sending you lots of best wishes for a positive outcome x

Ditto

I am sorry some people feel the need to criticise you, the position you are in is scary, frightening and you are doing all you can. Please ignore the negatives.
You came on here for advice, and I understand why, on balance I would respect my husbands wishes, but I understand you have fears and concerns. I wish your husband well.

Was DH ok when they left on holiday? Is this something completely new out of nowhere? What do the experts say in terms of likely outcome?

Given DH and siblings stance on this I think you need to wait. What would the ILAWs they do if they were there? It's only a few days until they are back. I am sorry OP and I wish you all well.

His illness, his mum, his decision.

I'm Hoping the diagnosis is the best case scenario for you

Given what you have said, I would contact her.

I would definitely tell her and I don't like my MIL. But DH is comforted by her presence. My DH suffers from the old stuff upper lip!

I’m so sorry OP. I would do what I felt was right and very likely I would tell my PIL. I wouldn’t feel bad about overriding my DH wishes. In fact in a medical situation (not as serious but we didn’t know that) I did exactly that. DH admits now it was totally the right thing to do.

Im so sorry that you are in this situation and that this thread has not been helpful. Just to back @BruFord s point, when my dh was ill people were really willing and glad to help out with our kids, I became very aware of how there is a deep human satisfaction in really being helpful and useful.

Is your dh in a calm enough place to consider his mum's pov here? I do honestly think there's a high chance she'll be quite hurt when she finds out she's been kept in the dark. Can you gently put this thought to him? It actually sounds as though you would benefit massively from her support too. I wish you and your dh all the very best of luck as you navigate this awful situation 💐💐

Every time one of my family has been through testing for something, both benign and cancerous outcomes, and didn't tell me about the testing because "they didn't want to worry me" I've always hated it when I found out. I hate that they were going through that and I wasn't able to support them.

My son was deathly ill in the spring, we were local but only visited once briefly because of this. My DIL was able to be there daily fortunately. We were updated a few times a day if he was having scans, MRI etc

I don't know if I could have forgiven if I had not been informed.

I would want to know. It would be my choice if I decided to come back but I’d want the choice.

I was actually watching for the ambulance to arrive for DH when DD rang up from holiday. I put on the performance of a lifetime, she never twigged.

I think she was glad I hadn't told her but also annoyed. I would do it again.

He's still alive by the way, but not curable.

Just ignore the people scolding you and turning an innocent question into a chance to score imaginary points about “private medical info” or your family relations. Needless to say you would not be doing anything wrong to have sny kind of conversation you need to have with your dh or his mother. Just do what makes sense to you. Snd be kind to yourself!