UHG is the second most overcrowded hospital in Ireland today, with 44 patients waiting on trolleys in the emergency department.
At Portiuncula Hospital in Ballinasloe there are seven patients without beds, five in the emergency department, and two in the wards.
Figures from the Irish Nurses and Midwives Organisation show that there are a total of 475 patients in Irish hospitals on trolleys today.
The worst affected hospital is UH Limerick, where there are 51 patients without beds.
Both hospitals are also coping with large numbers of COVID cases, which have begun to surge again in recent days.
There were 63 confirmed cases at UHG as of Thursday evening, with another 29 at Portiuncula Hospital.
Of those, three cases in Ballinasloe and two in Galway are being treated in the intensive care unit.
Portiuncula has just one general and one ICU bed available, while UHG has just no intensive care beds available.