A forensic pathologist from the British Home Office says New Zealand doctors' conclusions regarding Charlene Makaza's death were "erroneous".
George Gwaze, 60, is on trial for the murder and sexual assault of the 10-year-old girl in Christchurch in January 2007.
Mr Gwaze adopted her as a baby in Zimbabwe and brought her to New Zealand with his family. He denies that he violated and strangled her in their home.
The Crown says girl died after a forceful sexual attack by the accused, but the defence says she died of toxic shock arising from her HIV.
Forensic pathologist Nathaniel Carey examined post-mortem photographs of Charlene Mazaka and gave evidence via video link from England on Wednesday.
Dr Cary told the Christchurch High Court he saw no signs of bruising caused by any kind of force around the girl's genital area.
He said over-zealous clinicians can see injuries where there aren't any, and his microscopic examination superseded clinical impressions that are prone to human error.
"We had a horrendous problem in the United Kingdom a few years ago in Middlesborough where some clinicians got over-zealous and they started to imagine anal abuse in all sorts of children, and a large number of children were taken into care improperly as a consequence.
"So this is an area where you have to be really careful if you see abnormality, if you're diagnosing dilatation."
Dr Cary said Charlene Mazaka was probably born with her HIV infection so it had 10 years to manifest to the advanced form that killed her.
However, under cross-examination from Crown prosecutor Brent Stanaway, Dr Cary said he could see why emergency medics assumed that the girl had been assaulted.
Dr Cary agreed it was reasonable for treating clinicians to assume that Miss Mazaka had suffered a blunt force trauma, given the damage her HIV disease had caused.