Well, it's a mixture of symptoms really. This is what they did with me:
1 - They will monitor the baby for a good while - maybe half an hour? - just to check that it's heart rate is doing normal things.
2 - They will take your blood pressure regularly, maybe every 15/30 minutes for an hour or maybe two.
3 - They may do a blood test
4 - They will check urine for protein (again!)... and if they're worried they might admit you for 24 hours to do a "24 hour urinaylsis" which means you get stuck on a ward for overnight and every tiem you pee it has to be collected in a big bottle, so they can see your average protein over that time, just to check that it's not as a result of a particular meal or something.
5 - They may check your reflexes (hammer on the knees/ankles etc) as very brisk reflexes can be a sign...
6 - Ask you about your headaches/any visual symptoms - blurring, starts/spots in front of your eyes etc etc. They will look at your puffy feet (and see if they agree with your mum!).
7 - Might send you for an ultrasound just to see if the baby seems to be the right size for dates.
8 - They may prescribe some methyldopa (that's the drug name, it might have a different pharmacy name) to lower your BP for a week or two, but it will depend on your circumstances.
They may well discuss doing an induction/c-section with you. Ask as many questions as you can, and then ask again when you've had a chance to think about things. If they just talk about c-section, ask them if an induction would be possible. They will give you very clear reasons why this would be/not be a good idea. But this is further down the line, just thought I'd put everything on here, in case you ahve a busy afternoon with them!
I was very very lucky where I was, so maybe make a list of these checks and if they seem to be doing only one or two things, ask them about the rest. They might think you're a pain, but this is you and your baby we're talking about! An informed mother is a safe mother I think.......and they should be able to reason why they're not doing some of the tests if they don't htink they're necessary.
Make sure you have your notes/they have them. They need to see the pattern/amount your bp has changed. Maybe take a slightly bigger handbag with a spare pair of knickers/a toothbrush, just in case they want to admit you - I doubt you need your hospital bag just yet though
I'm on my way to bed now, in Oz, but will look out fo your in the morning!
Oh, and despite all this - please don't worry, they take this very seriously, and will not let you get ill!