Necrotising Enterocolitis (NEC)
NEC is a haemorrhagic necrotising inflammation of the intestinal wall that most commonly affects the distal ileum and proximal colon
Causes and Risk Factors
Primary risk factor: prematurity [Ref1][Ref2]
- Preterm infants have immature GI tracts with poor peristalsis, high mucosal permeability, and reduced secretion of digestive enzymes and protective gastric acid
Other risk factors: [Ref1][Ref2]
- Low birth weight
- Formula milk feeding
- Prolonged empirical antibiotic exposure
- Reduced intestinal perfusion (e.g. congenital heart disease)
- Gastric acid-suppressing medications (PPIs or H2 antagonist)
Clinical Features
| Local GI features |
|
| Systemic features |
|
Features of severe NEC: [Ref1][Ref2]
- Abdominal wall erythema / discolouration / oedema
- Shock
- Respiratory failure
Investigations and Diagnosis
Blood Tests
Key tests and possible findings in NEC: [Ref1][Ref2]
| Blood test | Finding and/or rationale in NEC |
|---|---|
| FBC | Neutrophilia may occur
Thrombocytopenia and neutropenia are associated with more severe disease |
| U&Es | Assess electrolyte disturbances, including hyponatraemia, and renal function |
| Blood gas | Metabolic acidosis and ↑ lactate may suggest tissue hypoperfusion or bowel ischaemia |
| Inflammatory markers | ↑ CRP +/- ↑ procalcitonin |
| Coagulation screening | May show coagulopathy, including DIC in advanced disease |
| Blood cultures | To identify infections and guide antibiotic treatment
Blood cultures should be obtained before starting antibiotics, if possible (without delaying treatment) |
Imaging
Diagnostic test of choice: abdominal X-ray (AXR) [Ref1][Ref2]
The classic 4 AXR finding in NEC: [Ref1][Ref2]
| Staging (Bell’s) | Radiographic finding | Description |
|---|---|---|
| I | Bowel dilatation / ileus |
|
| II | Pneumatosis intestinalis – pathognomonic sign of NEC | Intramural gas (radiolucent lines outlining the intestinal wall) |
| Portal venous gas | Branching dark lucencies over the liver (indicating gas within the portal venous system within the liver) | |
| III | Pneumoperitoneum | Free gas within the peritoneal cavity, such as:
|
NEC Staging
Deitch-modified Bell staging for NEC: [NHS GGC]
| Stage | Classification | Clinical features | Radiological features |
|---|---|---|---|
| I | Suspected necrotising enterocolitis |
|
|
| II | Proven necrotising enterocolitis |
|
|
| III | Advanced necrotising enterocolitis |
|
|
Complications
Acute complications: [Ref1][Ref2]
- Intestinal perforation → peritonitis → sepsis → septic shock → death
- NEC-induced acute lung injury
- Severe metabolic and haematological derangements
- Lactic acidosis
- Thrombocytopaenia
- Neutropaenia
Long-term complications: [Ref1][Ref2]
- Short bowel syndrome and intestinal failure (in those requiring surgery) → parenteral nutrition dependency
- Intestinal strictures / stenosis / fistulas
- Neurodevelopmental disorder and cognitive deficit (as systemic inflammation disrupts the BBB)
Management
Approach:
- ALL patients → conservative / medical management
- Selected patients → surgery
Conservative / Medical Management
| Bowel rest [Ref1][Ref2] |
|
| Broad-spectrum antibiotics + antifungal [NHS GGC] |
|
| Systemic support [Ref1][Ref2] |
|
Surgical Management
Do NOT routinely offer surgical management to ALL patients with NEC.
It is reserved for severe NEC or those refractory to conservative management.
| Indications for surgery [Ref1][Ref2] | Absolute indication: pneumoperitoneum on abdominal X-ray
Relative indications:
|
| Surgical options [Ref1][Ref2] | Primary option: laparotomy (necrotic bowel resection followed by stoma creation or primary anastomosis)
If unfit for surgery (e.g. extremely low birth weight, unstable for surgery) or as a temporary measure: primary peritoneal drainage |
Antenatal corticosteroids in pre-term delivery reduces risk of NEC, beyond its benefit in reducing NRDS and IVH. [Ref]