Medical consent procedures may need to be reviewed in the wake of new research by the University of Otago.
A new study of incidental findings - when a surgeon finds another issue unrelated to the operation they were performing - has found both patients and doctors favoured treating the unexpected problem that had been discovered.
However, many doctors were uncertain whether the consent forms their patients had signed actually permitted them to do so.
Ethical and legal issues were also a concern. An operation without consent could mean a surgeon might be subject to disciplinary proceedings, or could provide grounds for a claim of negligence.
''Despite such constraints, at least some surgeons are willing to undertake additional procedures under certain circumstances,'' the research, published in the NZ Medical Journal, said.
''Some institutions have used broad consent clauses to cover these effects.''
The study looked at both international and national consent forms and found a wide range of approaches to the question of incidental findings, from surgeon's discretion to strict prohibition.
It recommended a step be incorporated in the consent process for surgeons to clarify with patients what to do if an incidental finding was made.
''We endorse including such a clause in the consent process provided that this does not give inappropriate licence to treat, but that it will prompt a meaningful discussion and comprehension of the patient's preferences.''
Streamlining consent would also address what the study termed an apparent disjunction between a strict interpretation of the law and common practice by surgeons.
The researchers were also concerned about issues at either end of the spectrum - surgeons who would perform risky operations on low-impact anomalies without specific consent, and doctors who would likely not operate when risks were slight but the unexpected discovery was immediate and serious.
''While it is plausible that such decisions may be appropriate in rare circumstances, as a general approach they would raise questions about clinical reasoning.''
The researchers sent questionnaires to all surgeons and trainee surgeons in New Zealand and one-third responded.
Most, 91%, said they would treat an incidental finding if risk to the patient was low, but that dropped to 38% if the additional risk was high.
Patients were also consulted and 75% of 699 questioned were happy for an incidental finding to be treated.
However, as with surgeons, acceptance of additional treatment varied depending on severity of the issue and how risky the treatment was.
