Sentinel lymph node study

I had an appt for sentinel lymph node study today. This is to identify if cancer cells spread to lymph nodes. They inject a small dose of a low-level radioactive tracer. I thought it would be completed and get a result today. They will continue the rest of procedure tomorrow during the surgery. so no result today. They had to inject 4 times in the region. It was so painful! It hurt. I had to scream on the first one. I cried and screamed from second one. I was such an wimp... I didn't know my pain tolerance level was that low.