The standard of non-clinical services at Perth's Fiona Stanley Hospital have been given a pass mark, more than two years after Serco was stripped of its contract to sterilise surgical equipment after a contamination scandal.
Surgical equipment was returned in at lease one case with bone fragments still attached, but the company still provides sterilisation support and all other non-clinical services such as supplies management and general cleaning.
Auditor General Colin Murphy said on Wednesday they were being provided at an acceptable standard.
But he also said resolving contract disputes with Serco was proving time-consuming and costly.
"Current contract disputes are estimated at between $6 and $7 million and differences of interpretation could add significant costs to the contract," Mr Murphy said.
"Although service delivery has not yet been affected, the longer the disputes are, the greater the risk to service continuity."
Mr Murphy also criticised the South Metropolitan Health Service for not tracking cost performance effectively, saying costs had blown out by $24.6 million over the past two years because patient numbers had grown faster than expected.
The public hospital was the first in WA to have all non-clinical services outsourced.
The Labor state government has blamed the contract woes on privatisation, as it did in opposition.