Ar 1 Rhagfyr 2015, cyflwynodd Cymru system feddal o optio allan ar gyfer cydsynio i roi organau, a hi oedd y wlad gyntaf yn y DU i wneud hynny. Mae hyn yn golygu, os nad yw unigolyn wedi cofrestru penderfyniad i roi organau (optio i mewn) na phenderfyniad i beidio â rhoi organau (optio allan), ystyrir nad oes ganddo wrthwynebiad i roi ei organau – mae hyn yn cael ei alw yn gydsyniad tybiedig.
On 1 December 2015, Wales became the first country in the UK to move to a soft opt-out system of consent to organ donation. This means that if a person has not registered a decision to become an organ donor (opted in) or a decision not to become an organ donor (opted out), they will be considered as having no objection to being an organ donor – this is known as deemed consent.