Dr Nanikram Vaswani admitted misconduct in relation to the incident which happened after a different patient was brought into theatre at Broadgreen Hospital in Liverpool.
The man, known only as Patient A, was scheduled to have scar tissue removed, but Dr Vaswani performed a vasectomy instead.
He told the Medical Practitioners Tribunal Service that he had been expecting to operate on a man requiring a vasectomy, but that patients were being brought into theatre in the wrong order.
After admitting the blunder to his patient, he later tried to reverse the procedure – despite not having performed such an operation for five years.
Dr Vaswani admitted four charges of misconduct in failing to confirm the patient’s correct identity, failing to tell a urologist or the NHS trust about his mistake and carrying out the vasectomy reversal procedure.
‘Patient A’ was described as physically and emotionally traumatised by his ordeal, the panel heard.
But after taking into account Dr Vaswani’s genuine remorse and good character, the tribunal decided to allow him to carry on practicing.
He was instead given a warning which does not restrict his registration or affect his ability to practice medicine.
Ian Cohen, a clinical negligence specialist at Slater and Gordon, told the Daily Mail that compensation could run into tens of thousands depending on the age of the patient and whether he had been left infertile. The outcome of the vasectomy reversal is not known.
Mr Cohen said: “If a 25-year-old who wants a family is told he won't be able to father children it will be devastating.”