What a nasogastric tube is
A nasogastric (NG) tube is a thin, soft tube passed through the nose, down the oesophagus and into the stomach. On a neonatal unit, it is used routinely for feeding, for aspirating gastric contents before a feed, and for decompressing the stomach. It is not a sealed, pressurised conduit. It is a passive tube whose proximal end is either capped, connected to a syringe, connected to a gravity feed bag, or left open to air.
What “air in stomach” means clinically
Air in the neonatal stomach is a near-universal finding. Babies swallow air when they cry, when they breathe vigorously, when they are resuscitated, when they are fed. Air in the stomach can also build up from positive-pressure ventilation, particularly continuous positive airway pressure (CPAP) delivered via nasal prongs or mask. “Air in stomach” on an abdominal X-ray of a neonate is a routine finding; the clinical question is whether the quantity is causing distension severe enough to compromise diaphragmatic movement and therefore ventilation.
The default interpretation of air-in-stomach on a NICU is therefore: something routine, monitor, aspirate with the NG tube if necessary. The pathological interpretation is a step or two removed from that default.
What the prosecution argued
The Crown’s theory on several counts was that Lucy Letby deliberately injected air into infants’ stomachs via their NG tubes, causing gastric distension, respiratory compromise and collapse. The mechanism was described at trial as physically feasible (attach a syringe, push in air) and clinically harmful (enough air, enough distension, sufficient to cause deterioration).
Why independent neonatologists do not accept the mechanism as proof
Independent neonatology review — including the Panel, Dr Michael Hall, Prof. Hummler’s respiratory expertise on the Panel, and the published paediatric radiology literature — raises several structural objections to treating “air in stomach” as a diagnostic sign of deliberate injection:
- Non-specificity. Any source of air in the stomach can cause the radiological finding. Positive-pressure ventilation (routine on the unit) is the most common cause. Swallowed air during distress is the second. Air deliberately injected is not distinguishable radiologically from air that got there by other routes.
- Volume implausibility. To cause respiratory compromise via gastric distension, the volume of air required is not trivial. Clinically significant distension requires much more air than can be pushed in unnoticed in the interval between routine nursing checks on a NICU.
- Monitoring context. A neonate on a NICU is continuously monitored: heart rate, respiratory rate, oxygen saturation, often temperature. A rapid, deliberate event of air injection sufficient to cause collapse would show on those monitors. The observed patterns of collapse do not match the signature of a discrete, rapid air-injection event — they match the signature of gradual deterioration from a primary cause (NEC, sepsis, respiratory failure).
- NEC as competing explanation. Evolving necrotising enterocolitis produces abdominal distension, bilious aspirate, pneumatosis intestinalis on X-ray, and rapid circulatory deterioration. This constellation was misread in several indicted cases as “air in stomach” deliberate tampering when it was, on independent re-reading, NEC. See evidence: NEC natural pathology.
- Absence of contemporaneous forensic investigation. At the time of the alleged events, no NG-tube equipment was sequestered for forensic analysis, no syringes were preserved, no air-volume measurements were taken. The mechanism as reconstructed for trial rests on forensic inference from later reading, not on contemporaneous investigation of the alleged equipment chain.
The pathology of air in the GI tract
Paediatric pathologists reviewing post-mortem bowel material in the relevant cases have identified findings consistent with NEC pathology: pneumatosis intestinalis, portal venous gas, necrotic bowel segments. These findings are the diagnostic signature of NEC. They do not require — and are not specifically indicative of — deliberate air injection via NG tube. A paediatric pathology review applying modern differential-diagnosis methodology would include NEC as a primary differential on any case where these findings were present.
Why this matters for specific counts
The NG-tube air-injection theory was the prosecution’s mechanism on several counts, including cases where abdominal signs dominated the clinical picture. If the mechanism does not withstand differential-diagnosis scrutiny, the individual counts relying on it become, in the Panel’s view, unsupported by medical evidence of deliberate harm. That does not mean the babies did not deteriorate or die; it means the specific mechanism attributed to Letby is not what caused the deterioration.