I had my first colonoscopy at age 64, my platelet counts were around 50. My family doctor said the FiT test was just as good as colonoscopy but my hematologist/oncologist strongly disagreed. He said colonoscopy is the only way to check for pre-cancer and to catch cancer early so he referred me to gastroenterology. First gastro doctor refused to take me because I had ITP, wouldn't even consider it if I got my counts up. I found another guy who didn't care about my platelet count. I had one polyp removed, they cauterize that spot so no bleeding problems.
Perhaps there is an easier way to bump your counts up than IVIG? I was on Nplate. People usually respond to Promacta in 5-14 days. The prep is the worst part- I was on a clear liquid diet for 1-2 days (jello, broth, apple juice, tea) and then took a fizzy drink 2 times the evening before. Didn't get much sleep, hated the drink- gotta stay close to the bathroom. Another prep that is prescribed is a gallon of stuff you have to mix and drink the whole thing! The fizzy drink is better, it tastes fine, it just made me feel kind of dizzy.
The actual procedure is not bad, it took about 20 min. I was knocked out with propofol but most people are semi-awake with other drugs. I felt fine afterwards. You must have someone drive you home and you'll need to sleep it off for the rest of the day. Good luck!