The bypass began at 3.40pm but the emergency department remained open to the 89 people who self-presented for treatment.
�A large amount of doctors were on sick leave so we implemented bypass for reasons of clinical safety,� a hospital spokeswoman said.
During the diversion period, nine patients were taken to other hospitals.
Six patients were taken to RGH and three patients to Fiona Stanley Hospital.
The bypass was lifted at 8am on Monday and the hospital is now fully staffed and operational, the spokeswoman said.