What the prosecution alleged
In the counts relating to Children C, G and P, the Crown alleged that Lucy Letby deliberately introduced air via a nasogastric (NG) tube. The prosecution theory was that large volumes of air, once forced into the stomach through the tube, would migrate into the bowel, enter mesenteric vessels, pass into the portal circulation, and ultimately cause cardiovascular collapse or haemorrhagic injury consistent with the deteriorations observed. Dr Dewi Evans, the prosecution’s lead expert, described this pathway as physiologically plausible based on post-mortem and radiological findings he interpreted as gas in the bowel or portal system.
The prosecution treated the presence of bowel gas in post-mortem or X-ray images as corroborative of the NG-tube mechanism — even though bowel gas is a universal finding in neonates and does not by itself indicate any abnormality, let alone a deliberate act.
How a nasogastric tube actually works
A nasogastric tube is a thin, flexible tube inserted through a nostril, down the oesophagus, and into the stomach. In neonatal intensive care it is used for feeding, gastric decompression, and medication delivery. Critically, the tube terminates in the stomach. It does not have a direct conduit to the vascular system.
The stomach is a compliant muscular organ. When large volumes of air are introduced into the stomach of a neonate, the stomach distends. This distension can cause discomfort, regurgitation and bradycardia via vagal stimulation — a well-documented phenomenon that clinicians manage routinely by aspirating the tube. However, the stomach does not directly communicate with mesenteric venous channels in a way that would allow bolus air to enter the portal circulation at speed and volume sufficient to cause the acute cardiovascular events alleged.
The mucosal barrier of the stomach and small bowel is a genuine obstacle to gas entry into mesenteric veins. Gas can enter the portal system, but this occurs in the context of severe mucosal disruption — most commonly in necrotising enterocolitis (NEC), a recognised complication of extreme prematurity. NEC was itself a live natural-cause differential in several of the indicted cases.
Why injected air does not redistribute as alleged
The prosecution’s mechanism required that air introduced via the NG tube would transit from stomach to bowel, then through the bowel wall into the mesenteric venous system, and accumulate in sufficient quantity to produce lethal or near-lethal vascular compromise. Each step in this chain faces physiological barriers.
- Gastric-to-duodenal transit time. Air introduced into the stomach does not rapidly transit to the small bowel. Pyloric tone in neonates, particularly preterm neonates with immature gastrointestinal motility, substantially delays gastric emptying. Large air boluses are typically eructated or aspirated before significant duodenal transit occurs.
- Bowel-wall integrity in non-NEC neonates. The mucosal lining of the small bowel is intact in neonates without NEC or significant ischaemic injury. Intact mucosa does not allow free gas passage into mesenteric veins. The prosecution’s mechanism would require wall disruption that would itself be a primary pathological finding — one not documented in the affected infants’ records.
- Volume and pressure constraints. The volume of air required to produce systemic haemodynamic compromise via a portal-gas route is substantially higher than a carer could introduce through an NG tube without producing immediate, visible gastric distension so severe it would be detected by any nurse or clinician present. No contemporaneous clinical record in any of the three cases documents visible gross gastric distension at the time of alleged introduction.
Independent paediatric gastroenterologists, when reviewing the proposed mechanism, have characterised it as physiologically implausible for the reasons above. The Panel’s review reached the same conclusion: the NG-tube pathway, as described by the prosecution, does not produce the haemodynamic consequences alleged.
What independent paediatric gastroenterology says
Paediatric gastroenterologists who have reviewed the prosecution mechanism outside the context of the trial have noted several specific problems beyond the transit-and-wall-integrity issues:
- Hepatic portal gas on imaging is a well-recognised finding in preterm infants with NEC, sepsis and ischaemic bowel injury. Its presence on post-mortem imaging does not distinguish between NEC-associated gas production and gas introduced via the gut lumen from an external source.
- Post-mortem gas redistribution is an established artefact. Gas moves after death as tissue decomposition begins and vascular pressure gradients collapse. Post-mortem radiological images taken hours after death are not reliable indicators of the ante-mortem gas distribution.
- Positive-pressure ventilation — which all three infants received during resuscitation — can itself force air into the gastrointestinal tract via an incompetent oesophageal sphincter, producing the same imaging appearance the prosecution cited as evidence of deliberate air introduction.
The Shoo Lee Panel, in its case-by-case review, identified natural and resuscitation-associated mechanisms that fully account for the imaging findings without any deliberate act.
What this implies for the Children C, G, P counts
The Crown’s NG-tube mechanism was central to the counts involving Children C, G and P. If the mechanism is physiologically unsound — as independent gastroenterology and the Panel conclude — then the physical basis for those counts dissolves. What remains is a pattern of presence (the shift-chart argument) applied to deteriorations that have natural-cause explanations.
Child C was a 23-week infant on whom the Panel identified features consistent with extreme prematurity complications. Child G experienced a deterioration in the context of an acute infectious episode documented in the ward record. Child P was one of the triplets (Baby P, triplet brother of Babies O and Q), whose deaths occurred in the context of a high-risk triplet pregnancy trajectory, for which the Panel provides a unified natural-cause reading.
In each case, the alternative to the NG-tube mechanism is not a mystery — it is a documented clinical context of extreme prematurity, infection, resuscitation events and unit-level factors consistent with the full Datix and clinical-record picture.