Doctors are concerned bowel screening patients are not getting enough information with their test results.
While it's the second highest cause of cancer-related death in New Zealand, bowel cancer can be treated successfully if detected early.
But some doctors say certain tests are oversimplified.
When a patient's stool sample is tested, they'll get a result of "positive" or "negative".
But some doctors argue that approach could be putting patients at risk.
"The test measures how much blood is in your motions. It's not uncommon to have a little bit, but it's about the volume that's in there that matters. And it's about whether you reach a certain threshold, which will indicate that you need a colonoscopy," said Phil Bagshaw, a general surgeon.
Authors of a letter published in the New Zealand Medical Journal want patients to know exactly how much blood per milligram there is in their sample, particularly if there's a family history of bowel cancer.
They say patients might assume a "negative" result means there's no evidence of blood, which could be misleading.
"It's about patients' rights and it's about the fact that they have a right to know their results. Doctors have no right to keep anything from patients. They own the results so if the patient wants the results they're entitled to have them," Mr Bagshaw said.
Bowel Cancer New Zealand medical advisor Professor Frank Frizelle said: "It's going to create a large grey zone, which is an issue. Patients generally want a clear idea."
The Ministry of Health says New Zealand's system is consistent with international process.
Patients can apply for those results.
And if in doubt, the advice is to see your GP.
"There may be other tests that can complement this. And the GP will take a decent history, examine the patient, and add a bit more of a dimension or matrix to the decision making," Professor Frizelle said.
Three quarters of bowel cancer cases are curable if caught early.
The hope is that patient power through information will see that number rise.