The female medicos have described the litany of gender biases that disparage motherhood, erode their credibility, objectify their bodies and shoehorn them into stereotypical "empathetic" roles (and high heels).

Forty-eight women fellows and trainees of the Royal Australasian College of Surgeons took part in a series of in-depth interviews for a study led by research fellow Dr Katrina Hutchison at Macquarie University's Department of Philosophy.

Dr Hutchison said the pattern of "micro-inequities" may seem inconsequential, but their compounding effect could do lasting damage and stymie efforts to close the gender pay gap.

One interviewee described a patient's incredulous response to her surgical fee, saying "she's just a female doctor. Why is that really expensive?"

Others have recounted instances where patients failed to recognise that the woman performing the tasks of a surgeon - including explaining their surgery and gaining consent - was indeed their surgeon.

Plastic and reconstructive surgeon Dr Neela Janakiramanan said several patients had asked her "when will I see a surgeon" despite her having introduced herself as their surgeon and had detailed discussions about their operation.

"Only last week a female patient said to my secretary: "what do you mean a female surgeon? They don't exist," Dr Janakiramanan said.

"That is the most egregious comment I've come across, but we constantly come up against these unconscious biases."

Dr Janakiramanan said the 'old boy's club' of surgery was "genuinely changing, but there is still a penalty against women", in which women with children were doubly penalised.

It was a common theme among the female surgeons interviewed by Dr Hutchison, one female surgeon recalls a group of male surgeons deriding a female colleague as "a crap surgeon" because she was "off having babies".

"If you're a female trainee standing there operating while the boss is talking about this, about another female consultant, of course that affects you," she said.

There was also an expectation that female surgeons put up with "low-level harassment" and objectification.

One female surgeon describes being told "it's a good thing you're a pretty face, surgeons like having a pretty face in theatre".

Others described an implicit expectation that they wear high-heels, despite the impracticality.

Dr Janakiramanan said implicit gender biases were inescapable, "very slow and insidious".

For instance, a female trainee is not privy to the conversations in the male changerooms where senior surgeons discuss upcoming operating plans with a male trainee.

That male trainee has inadvertently received better training than the female one and may seem more competent as a result, Dr Janakiramanan said.

This kind of "edge" had flow-on effects for a surgeon's career, she said.

RACS data shows 11 per cent of consultant surgeons are female in Australia and New Zealand.

Women are also leaving mid-surgical training in greater numbers, despite evidence that they may be more able.

A separate study published in February found sexual harassment, bullying and contempt for motherhood are driving aspiring female surgeons out.

Dr Hutchison found female surgeons were also expected to be more empathetic, which led to greater demands on their time both in counselling patients, and being the "peace-makers" for colleagues.

"If there is an angry patient they'll want the girl to talk to them. You have to do a lot more kind of talk-talk and touchy-feely stuff," one female surgeon said.

"If women surgeons respond to apparent views about their lesser worth by charging lower fees, this contributes to the pay gap," Dr Hutchison said.

"If they charge lower fees while meeting increased demands on their time ... the problem will be exacerbated."

"The stereotype is a burden, but many female surgeons use it as an advantage," Dr Janakiramanan said, "and there are many kind, wonderful male surgeons as well".