Hello Melody

I cannot say what exactly blood pressure that would trigger you to go to the hospital; there is no magic number here. 

Several ideas for you, though.  One, and importantly, if you are experiencing any symptoms at all, you need to immediately go to the ER.  Symptoms include headache, blurry visions, chest pain, shortness of breath, decreased urine output, change in mental status, and back pain.  Secondly, if your blood pressure spikes higher than probably (I say probably, because honestly, there are no guidelines) 180/100 you need to call your primary care physician to get his opinion on whether your not you need to visit the ER.

Hope my answers help.

To your health,

Neil MD