Plain-English terms
Glossary
The case turns on technical medical, statistical and legal terms. Here are plain-English definitions, each with the context in which it appears in the Letby case.
- Air embolism
- A gas bubble in the bloodstream large enough to obstruct blood flow. Extremely rare in neonates. The prosecution theory in several Letby counts.
- C-peptide
- A protein released in equal quantity to insulin when the pancreas produces it. A low C-peptide with high insulin is therefore said to indicate the insulin came from outside the body.
- CCRC
- Criminal Cases Review Commission — the independent statutory body (set up in 1997) that reviews possible miscarriages of justice in England, Wales and Northern Ireland and can refer cases back to the Court of Appeal.
- Datix
- The NHS incident-reporting database. Every deterioration, crash call or unexpected event on a ward is supposed to generate a Datix entry.
- ET tube (Endotracheal tube)
- A flexible tube passed through the mouth or nose into the trachea to maintain an airway. Extremely easy to dislodge, especially in very small babies.
- Gross negligence manslaughter
- A criminal offence where a death results from a grossly negligent breach of a duty of care.
- Immunoassay
- A laboratory test that uses antibodies to detect a substance. Rapid and cheap, but known to give false positives; confirmatory mass-spectrometry is standard in forensic contexts.
- NEC (Necrotising enterocolitis)
- A devastating bowel disease of premature babies. One of the leading causes of neonatal death.
- RCPCH
- Royal College of Paediatrics and Child Health — the professional college of UK paediatricians, which performed a service review of COCH in 2016.
- Reporting restrictions
- Court orders limiting what may be published about a live trial, to protect the fairness of proceedings.
- Texas sharpshooter fallacy
- A statistical fallacy in which one selects evidence that fits a hypothesis, then presents that selection as proof of the hypothesis.
- Thirlwall Inquiry
- Statutory public inquiry into how the Countess of Chester Hospital and associated NHS bodies responded to concerns about deaths on its neonatal unit.
- TPN
- Total parenteral nutrition — intravenous feeding used when the gut cannot be used. Prepared in a pharmacy in sterile bags.
- Whole life order
- The most severe sentence in England and Wales: imprisonment with no prospect of parole. Imposed only for the most serious offences.
Context: The diagnostic criteria — including skin discolouration patterns — come from Dr Shoo Lee's 1989 paper, which he says was misapplied at trial.
Context: Prosecution relied on this in Children F and L. Endocrinologists point out the screening immunoassay used does not reliably separate insulin species in neonates.
Context: Reviewers note the 2015–16 Datix record at COCH neonatal unit shows a unit under severe strain — a pattern consistent with natural-causes explanations.
Context: Central to the Child K count.
Context: The offence on suspicion of which three former COCH executives were arrested in July 2025.
Context: The Roche insulin immunoassay at COCH was not followed up with confirmatory testing.
Context: Some Panel reviewers attribute several of the alleged 'air-in-stomach' cases to evolving NEC.
Context: Its review focused on unit configuration and did not examine individual cases.
Context: Applied during the Letby trials — the reason several international articles were geo-blocked in the UK.
Context: Used to describe the shift-rota chart shown to the Letby jury.
Context: Final report expected after Easter 2026.
Context: Prosecution alleged TPN bags were tampered with in the insulin counts.
Context: Letby is only the fourth woman in UK history to receive one.