The never event, named so because they are incidents that guidelines say should never happen, was recorded by Shrewsbury and Telford Hospital NHS Trust (SaTH) in October.
A report to the trust's board, outlining its latest performance figures, said that it involved a "wrong site surgery" – which is surgery performed on the wrong patient, the wrong body part or the wrong side of the body.
The full details of the incident have not been revealed but an investigation is under way.
"There were nine serious incidents this month [October]," the report says.
"These included a wrong site surgery never event, the first never event this year, which is being investigated and learning put in place to prevent a recurrence."
'Serious incidents' are described within the board papers as "adverse events with likely harm to patients that require investigation to support learning and avoid recurrence".
The number fell from ten in September to nine in October, but 59 serious incidents have been reported by the trust since April.
Serious incidents in October included a 'medication error', 'delayed diagnosis', the mis-reporting of a CT scan, a pressure ulcer and a number of falls resulting in a head injury or broken hip.
The report to the trust board says over the coming months Covid-19-related incidents such as delayed diagnosis due to access issues and outbreaks may continue to be seen.
The number of falls also continues to remain an "area of concern" with 127 reported in October, according to the report.
It said: "Three of the falls in October resulted in serious harm – one patient sustaining a head injury (ward 26), one patient sustaining a head injury and subsequent death (ward 28) and one resulting in a broken hip (ward 32).
"There were a further two falls which resulted in moderate harm.
"Investigations are under way."
It confirms that ongoing work continues to ensure all patients have a falls risk assessment on admission, care plans are in place for patients assessed as at risk of falls and re-assessments are completed weekly or when a patient’s condition changes.
Completed investigation reports are presented to the trust's nursing incidents quality review meeting, chaired by the deputy director of nursing, when learning is identified and shared.
The trust, which runs Royal Shrewsbury Hospital and Princess Royal Hospital in Telford, says all inpatient falls are also reviewed daily by matrons and the falls lead practitioner.
SaTH is also part of a 'regional falls group' which works to share learning and falls prevention strategies, and which has noted an increase in falls nationally.
The report says the trend may be linked to the pandemic.