1. Necrotising enterocolitis

2. Why you need to know about NEC
Scary
Very sick, very quickly
First signs:
Increased aspirates
Abdominal distension

3. Framework Most common GI emergency in the NICU 1-5% of admissions
GIT and systemic
Combination of factors (some known, some unknown):
Immature gut
Vascular insult
Metabolic insult

4. Who?

5. Risk factors Prematurity: Why prems? Younger more prone
10% of infants <1500g
Why prems?
Immaturity of motility (less mobile, more disorganised)
Greater permeability of gut (less barrier)

6. Risk factors (cont’d) Relative hypoxia: Acute insult (e.g. asphyxia)
Cardiopulmonary disease (that includes all the RDS babies!)
Polycythaemia (watershed areas)

7. Risk factors (cont’d) Enteral feeds: Rare in unfed infants
Breast-feeding lowers risk
Formula and stored EBM have less immunoprotective factors
?Mechanism: substrate for bug breeding (partial malabsorption of carbohydrate, fats; add relative dysmotility...)

8. Risk factors (cont’d) Feeding patterns – controversial:
?Rate of increase: no relationship (Cochrane database review)
?Timing of initiation of feeds: no relationship (Cochrane database review)
Minimal enteral or trophic feeds do not increase incidence of NEC

9. Why? Nobel Prize answer No clear unifying theory One possibility:
Loss of mucosal integrity (ischaemic/toxic): infarction
Bacterial proliferation (?aided by feeds)
Invasion
Transmural necrosis, perforation, peritonitis

10. When? Classically 2-3 weeks after enteral feeds introduced (prems)
First week of life (terms)
(Anytime: be on guard especially e.g. the NICU graduate feeding and growing in SCN)

11. Nursing observation sheet
Increased volumes of gastric aspirate
Bilious aspirate (2/3 cases)
Bloody stools
Temperature fluctuations
A&Bs
“Vitals” – evolving systemic shock

12. Abdominal distension – most frequent early sign (70%)
Firm, tender (baby doesn’t like palpation), perfusion

13. Changes in stool (bloody)
Worry when...
Abdominal distension
Feed intolerance
Changes in stool (bloody)
(especially when timing/set-up for NEC)

14. Immediate action Consider: Treat baby before chasing tests!
“Resuscitation”: things you can do before and while you’re chasing confirmation of diagnosis;
“Investigations”: seeking further weight to add to clinical suspicion of diagnosis
Treat baby before chasing tests!

15. Treating baby (“pre-investigation”)
Involve senior medical staff
Manage as acute abdomen:
Hold/stop feeds
Ensure NGT down
Treat shock (initial fluid bolus/es if required)
IV access (after ordering AXR) for resuscitation and bloods

16. Investigations AXR: supine and lateral decubitus Bloods: FBE U&Es
Blood culture (including anaerobic)
Blood gas
(CRP as baseline)

18. AXR findings Early: non-specific intestinal dilatation, oedema
Free intra-peritoneal gas
Portal venous gas (25%?)
Pneumatosis (70-80%)
Persistent, fixed sentinel bowel loop

19. Tangent 1 – Intraperitoneal gas
Supine AXR:
“Double wall sign” (Rigler’s sign)
Visualization of falciform ligament (Silver’s sign)
“Football sign” – abnormal lucency over liver, or central part of abdoemn
Morrison’s pouch (hepatorenal abscess) – visible free edge of liver

20. Intraperitoneal gas (cont’d)
Lateral decubitus:
Patient right-side up
May need to wait (up to 15mins) to allow air to rise!
Lateral shoot-through

21. Rigler’s sign (child post-VP shunt insertion)

22. NEC complicated by pneumoperitoneum
Rigler’s sign (white arrows); falciform ligament (black arrow); free air over liver; intramural gas in bowel in left lower quadrant

23. NEC complicated by perforation
“Football sign” (small black arrows); falciform ligament (large arrow)

24. NEC complicated by pneumoperitoneum
Air in Morrison’s pouch – the liver edge is outlined

25. Pneumoperitoneum
Subtle lucency outlined by arrows in image on left; pneumoperitoneum confirmed on lateral decubitus

26. Tangent 2 - Ultrasound
Portal vein U/S is more sensitive than AXR in detecting portal venous gas
Detection of pneumatosis

27. Ultrasound of pneumatosis

28. Bloods

29. Bloods findings FBE: U&Es: Gas: acidosis (metabolic or combined)
WCC: too high or too low
Platelets: too low (50%) – poorer prognosis
(Hb/h’crit: rule out polycythaemia as exacerbating factor)
U&Es:
Na+: too high or too low
K+: usually too high
Gas: acidosis (metabolic or combined)
(Blood group: especially if possible transfer)

30. Management Check previous management happening:
Nil orally (order TPN!)
NGT down (check position on AXR)
IV access
Fluid resuscitation/circulatory support (may need inotropes)

31. Management (cont’d) Antibiotics: Treat derangement of:
Usually triple (including anaerobic cover) e.g. ampicillin, gentamicin, metronidazole
Bacteraemia in up to 30%
Treat derangement of:
Electrolytes (Na+, K+)
Blood gas derangement (ventilation, fluid +/- NaHCO3)
Strict fluid balance (and watch urine output)

32. Decision-making
Appropriate site for management: here, or transfer to RCH (access to surgeons)
Liaison with RCH surgery and RCH Neonatal Unit (+/- NETS)
AXR for surgeons to view
If for transfer: resuscitation, medical optimization of baby’s status

33. Medical management Nil orally for 7-10 days (TPN)
Antibiotics for 10 days
?Peritoneal drainage (especially in VLBW)

34. Medical management (cont’d)
Respiratory support (abdominal splinting)
Inotropic support prn
Fluid, electrolyte management
Regular surveillance of abdomen for complications (e.g. perforation)

35. Surgical management Laparotomy Especially if perforation
Resection, stoma formation
May leave borderline bowel, opt for “second-look” laparotomy

36. Prognosis Serious illness: 20-40% mortality (NEC with perforation)
Laparotomy = major surgery
Degree of resection can have long-term consequences (e.g. short-gut syndrome)

37. Take home points (for regs!)
Beware nursing concern re big bellies and aspirates
Especially either on an upward trend
Bilious aspirate is never a good thing
Feel the belly every day
?Most important part of daily examination
Any suspicion:
Involve senior (hard diagnosis, serious illness)
Initial management measures (won’t harm baby)

38. Acknowledgements Images from: Royal Women’s Hospital, Melbourne.
Williams H. Perforation: how to spot free intraperitoneal air on abdominal radiograph. Arch Dis Child Educ Pract Ed 2006; 91: ep54-ep57.