Colleagues at Swansea Bay University Health Board are working to resolve the issue and re-submit revised data for the full period affected.
Mae cydweithwyr ym Mwrdd Iechyd Prifysgol Bae Abertawe yn gweithio i ddatrys y mater ac ailgyflwyno data diwygiedig am y cyfnod llawn yr effeithir arno.