GOV.WALES uses cookies which are essential for the site to work. Non-essential cookies are also used to tailor and improve services. By continuing to use this site, you agree to our use of cookies.
Mewn hap-dreialon clinigol, unrhyw un o'r grwpiau triniaeth. Mae o leiaf ddau grŵp o'r fath yn y rhan fwyaf o hap-dreialon, ond weithiau ceir tri neu ragor.