Is it required for a airplane to have a bathroom?

Question

I can remember a few years back my family and I had a short flight (maybe about 30 min) on a very small commercial plane...propellors, open cockpit..the works! I do not recall a bathroom being on this plane. Now that I have Chron's disease I constantly worry about bathroom placement. I am flying this weekend, is it possible to be on an airplane without a bathroom? Thanks