Ct scan and spinal tap question. please help.?

hi, i recently went to the hospital due to what i can only describe as the worst headache i've ever felt in my life! i was worried, so i had a ct scan performed. the doctor told me that the results came out normal, but that ct scans are only 95% accurate, therefore he recommended a spinal tap (which i refused at the time.) he wanted to make sure i didn't have an aneurysm. does anyone know why the ct scan has that 5% failure rate? is it due to us moving around and "blurring" the scans? also, i have a low paying job and i have no insurance. obviously, it is probably best to get the tap done. but realistically, i am worried about the cost and wondering if it is really necessary. i didn't really like the doctor much and he seemed like he was trying to scam me. he wasn't able to answer any questions i had, was very brief, and did nothing to make me feel comfortable. does anyone have any advise, perhaps from your own personal experience? thank you in advance!

The unfortunate fact is that no medical procedure is 100% accurate. The CT scan, as good as it is, can miss some things. The spinal tap is a way to detect any bleeding or any increase in pressure in your brain, both of which could be due to an aneurysm, it is can also detect other causes of headaches like infections in the brain. The spinal tap would probably catch anything the CT missed. The procedure is actually relatively quick. I really have no idea what it costs though.
Is it really necessary? It is up to you. A 95% accuracy is already very good. Of course some people would not want to take that 5% chance of something happening in the future.
Of course nothing is simple when finances are involved. It really depends on you what you want to do. If the headaches are gone, maybe you're alright. If they keep coming back, you definitely need to have it looked at. If you don't like your current doctor, you always have the option of seeing another one.

" Soy Bean Milk. "

He may have wanted the spinal tap to check you for Menningitis. But, I would CERTAINLY go for a second opinion before doing ANYTHING. You don't want to rely on a doctor who can't even answer your questions or spend time easing yur anxiety. Good Luck to you.