Air embolism — the Shoo Lee 1989 paper misapplied
Prosecution claim
The Crown argued that skin discolouration described on several infants — patches of pink surrounded by pale, almost marbled, skin — was diagnostic of air embolism, meaning air deliberately injected into the bloodstream via an IV line. The prosecution's expert drew the diagnostic criteria directly from Lee & Tanswell's 1989 Archives of Disease in Childhood paper.
Counter-evidence
Dr Shoo Lee, the lead author of that 1989 paper, has publicly stated that the skin signs described at the Letby trial do not match those in his research. The skin pattern in his paper describes a specific, large-vessel obstruction picture — not the patchy mottling described at trial. The 14-member Panel he subsequently convened reviewed every alleged air-embolism count and found none met the diagnostic criteria. Independent neonatologists add that the mottling described is a non-specific sign of any major circulatory compromise, including sepsis and natural collapse in a premature infant.
"The skin discolouration described in the Letby trial does not match the findings in our 1989 paper. There is no medical evidence of air embolism in any of these cases." — Dr Shoo Lee, 3 February 2025
What the jury heard
Dr Dewi Evans, the Crown's lead neonatal expert, presented photographs of post-mortem skin patterns and described them as classic findings of venous air embolism. He cited the Lee & Tanswell 1989 paper as the authoritative source for those criteria. The jury was told the skin signs themselves, combined with Letby's presence, were diagnostic.
What the Panel says
The Panel, chaired by Dr Lee himself, concluded that the skin patterns described do not satisfy the diagnostic criteria of the 1989 paper. The paper described a specific pattern associated with large-vessel obstruction — migrating bright pink vessels against pallor — which was not what was described at trial. The Panel therefore finds no medical evidence of air embolism in any indicted case.
What independent experts add
- Independent neonatologists note that non-specific skin mottling is routine in collapsing preterm infants from any cause — sepsis, shock, NEC, cardiac failure.
- No post-mortem radiology or imaging in any case showed the intravascular gas pattern that air embolism would produce.
- science4justice.nl has published a detailed line-by-line comparison of Lee's 1989 criteria with the trial descriptions.
- The Panel's finding has been independently endorsed by neonatologists in Canada, Sweden, Germany, Belgium, New Zealand, the UK, Taiwan and the United States.