Brendan Leigh Russell, known by moniker BSlice Dot Com, has pleaded not guilty to intentionally causing grievous bodily harm to the woman, who says she bled for days and was left in extreme pain.

The NSW Central Coast body modifier, 40, also denies responsibility for the death of a second customer and conducting an illegal genital mutilation on a third woman.

The identities of each woman have been suppressed by the court

The first woman told the Sydney District Court on Tuesday she knew Russell was not a plastic surgeon or a doctor when seeking the procedure in his all-in-one tattoo parlour and barbershop in Erina.

She had also previously had cosmetic surgery in a medical facility and was training to be a nurse.

But she says she went ahead with Russell after seeing photos of a previous patient, hearing Russell boast of praise from the medical field for his anaesthetic technique and hearing little about the risks.

"Whatever he was saying back then, he was so confident and very convincing and I felt like I was in really good hands and I felt he knew what he was doing," the woman said.

The procedure stemmed from a comment in mid-2016 in which the woman lamented the size of her stomach as her children's hair was cut in Russell's shop.

When Russell said he could help, she raised her desire for an "Elle Macpherson tummy" and asked, "am I going to look like that after?" the court was told on Tuesday.

Instead, after the procedure in the Erina Fair shopping centre, she suffered "extreme pain", substantial bleeding and required surgery a few weeks later.

Hobbling around Erina Fair with her sister in the days before Christmas 2016, the woman said Russell came up and spoke to her.

"Brendan stated 'look at the way you're walking, it looks like you've been f***ed up the arse," the woman said.

Under cross-examination on Tuesday, the woman denied the body modifier had actually opened with "how are you?".

"I suggest you said to him 'I'm fine, just a bit sore and tired' and that was the extent of it," lawyer Michal Mantaj said.

"No," the woman said, saying that as well as the "f***ed up the arse" line, he'd mentioned his search for presents, how he couldn't handle crowds and how he wanted to get out of there.

She also denied that Russell had said "of course I care" when he visited her at her home after her hospital surgery or that he'd offered her to refund the $800 cost of the procedure.

"No ... he suggested he could have fixed the problem for me and I didn't need to go to the hospital," the woman said.

"That (refund) was my husband and I - we decided we wanted a full refund for what I'd been through."

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The court was told the woman was told "nothing" in a pre-procedure consultation about the potential for wound bleeding or the risks of internal bleeding or infection.

"Internal bleeding was never ever spoken about," she said.

The woman denied suggestions the body modifier had described the tummy tuck as a "big procedure" or that his lack of a mask during the procedure was because she'd mentioned "it was intimidating".

"That is not what happened," the woman replied.

She also denied telling Russell in the days after the procedure: "I'm really sore I did something stupid, I tried to do a bit of work."

The trial continues.

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