Western Australia's hospitals have recorded an uptick in preventable serious incidents including medication errors and bungled surgeries.

Data released by WA Health highlights an increase in sentinel events - serious and wholly preventable clinical incidents that caused or could have caused serious harm or a patient's death.

There were 26 sentinel events resulting in two patient deaths in 2021/22, up from 19 events and six deaths the previous year.

Both deaths in the most recent year were linked to medication errors, while a further 12 medication-related incidents resulted in serious harm.

There were five instances where a patient had surgical or other invasive procedures performed on the wrong site, two of which caused serious harm.

Other serious incidents involved the wrong procedure being performed on a patient and the "unintended retention of a foreign object in a patient" after surgery or other invasive procedure.

Sentinel events are included in the total number of "SAC 1" events - clinical incidents attributable to healthcare provision, or lack thereof, that could have caused serious harm or death.

There were 574 SAC 1 incidents in 2021/22, a two per cent decrease from the previous year.

Of those, 139 resulted in death compared with 147 in the prior financial year.

Those outcomes may have been influenced by "multiple contributing factors" including complex medical conditions, WA Health said.

Health service providers recorded a 3.6 per cent increase in inpatient activity as measured by hospital bed days.

Chief Medical Officer Simon Towler said other indicators of patient safety highlighted improvements in the health system, including a drop in hospital-acquired complication rates for patients in recent years.

"WA Health continues to be committed to improving patient safety by reviewing incidents or potential incidents and developing clinical strategies to prevent these occurring in the future," Dr Towler said in a statement.

"Almost two-thirds of confirmed clinical incidents ... had a patient outcome of no harm.

"However, we need to consider every potential incident as an opportunity to examine where we can improve."