A man has been mistakenly given a vasectomy by medics who were supposed to be performing a "minor procedure" on him, a hospital in England has admitted.
The patient, who has not been named, went to the Royal Liverpool Hospital for a minor urological operation, but was wrongly made sterile by a blundering surgeon.
Medics tried to reverse the error but it is not known whether the reversal was successful.
Health bosses at the Royal Liverpool and Broadgreen University Hospitals NHS Trust said they have apologised "unreservedly" to the patient.
They said an internal investigation into the incident is under way and the responsible surgeon has been suspended from carrying out operations pending the result.
An operation conducted on the wrong body part is classed as a "never event" by health officials.
The incidents are regarded by the British government as so serious that they should never happen.
Between April and September last year there were 148 such incidents recorded by NHS England.
A vasectomy is a minor operation, where the tubes that carry sperm from a man's testicles to the penis are cut, blocked or sealed.
It is possible for a vasectomy to be reversed but the success rate is around 55%.
NHS guidance states: "Even if a surgeon manages to join up the vas deferens tubes again, pregnancy may still not be possible. This is why you should be certain before going ahead with the vasectomy."
Dr Peter Williams, medical director of the trust, said: "We can confirm that a patient who was scheduled to have different minor urological procedure was wrongly given a vasectomy.
"We greatly regret the distress that this has caused him. We have apologised unreservedly to the patient and we are offering him our full support.
"It is our duty, in the best interests of the patient, to uphold their confidentiality, therefore we cannot provide any further detail without their agreement.
"This is a serious incident and we are investigating this fully to understand why it occurred and how we can ensure it does not happen again.
"We take any incident such as this extremely seriously and report them at the highest level in the trust and to our regulators.
"Since this incident, the surgeon has not been carrying out any operations, pending the findings of the investigation. In addition we are carrying out routine checks on compliance with the WHO checklist and our surgical teams are compliant."