The first thing came to my mind that he might decided to go and see his baby
Jup. I think so too. Fargo probably created this cliffhanger so that we might panic and think: "Bihbhibivguvguguvgyvgy he's gone omg! He left the baby like his mother left him!" But I don't think Hyesung would do that, not after the last few chapters. AND even if he's gone, he'd be back in no time. :D
I hope they did not take him somewhere because of health problems. T.T
If he went to the toilet tho wouldn't they take the IV strip with them?
I was thinking maybe a doctor or a nurse transferred him or took him somewhere else like the toilet maybe?