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Necrotising Enterocolitis

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Welcome to your first day with the neonates! Upon arriving for your initial shift, you set down your bag, and shortly after, you’re asked to evaluate Baby A.

Baby A, a preterm infant, appears to be faring well for the moment—requiring minimal respiratory support, on full feeds, without IV access, and generally in an okay condition. However, their nurse expresses concern, noting that they seem slightly “off.”

Everything appears okay upon examination and review of their observations. Nonetheless, you were extra cautious, requested a blood gas, conducted a thorough examination, and found that everything was within normal limits.

You hand over, head home, and upon returning the next day, you’re greeted with the news that Baby A is now intubated, ventilated, receiving nil by mouth, and on IV antibiotics for suspected necrotising enterocolitis (NEC).

Could anything have been done differently? Did you overlook anything?

Let’s delve into the significant challenges small bellies pose: big battles – the not-so-simple case of necrotising enterocolitis.

The history of necrotising enterocolitis

The earliest documented cases resembling Necrotising enterocolitis (NEC) date back to the late 19th and early 20th centuries. However, it wasn’t until the 1950s and 1960s that NEC emerged as a significant clinical problem, coinciding with advances in neonatal care that improved premature infant survival rates.

The term “necrotising enterocolitis” was coined during this period. By the early 1970s, NEC was increasingly recognised as a serious condition affecting neonates, particularly those who were born prematurely or had other underlying health issues.

NEC remains a significant challenge in neonatology, prompting ongoing research and clinical trials to better understand its pathogenesis, improve prevention strategies, and develop more effective treatments. The advent of newer technologies, such as advanced imaging techniques and genomic studies, offers promising avenues for early detection and personalised treatment.

What is the incidence and prevalence of NEC?

In the United Kingdom

In the UK, the incidence of NEC varies significantly with gestational age and birth weight. Among neonates admitted to neonatal intensive care units (NICUs), the incidence rates range from 1% to 5%.

The highest-risk group comprises preterm infants, particularly those born at less than 32 weeks of gestation and weighing less than 1500 grams. The incidence of NEC is notably higher in this group.

The variability in incidence rates reflects differences in neonatal care practices, the population of neonates under care, and the diagnostic criteria used.

In Australia

Australia reports a similar incidence, with a focus on very low birth weight (VLBW) infants who are most at risk.

According to data from the Australian and New Zealand Neonatal Network (ANZNN), the incidence in this group is estimated to be between 2% to 7%. The wide range can be attributed to regional differences in neonatal care, the prevalence of risk factors, and the vigilance in diagnosing the condition.

Despite advancements in neonatal care, NEC remains a significant concern due to its association with adverse outcomes, including prolonged hospitalisation, the need for surgical intervention, and increased mortality rates.

What is the pathophysiology of necrotising enterocolitis?

The pathogenesis of NEC is complex and multifactorial, involving the interplay of intestinal immaturity, microbial colonisation, and an exaggerated inflammatory response.

Premature infants have an underdeveloped gut barrier function, decreased gastric acid secretion, and a relative paucity of protective gastrointestinal flora, making them particularly susceptible to NEC.

Introducing enteral feeding in this vulnerable population can provoke an inappropriate inflammatory response, leading to mucosal injury, bacterial translocation, and, ultimately, necrosis of the intestinal tissue. This process is exacerbated by pathogenic bacteria and an immature immune system failing to adequately regulate the inflammatory response.

This doesn’t translate to not feeding preterm infants, but it makes us a bit more cautious about how to go about introducing enteral feeds in preterm infants.

Risk Factors for NEC

The pathogenesis of NEC is multifactorial, involving a combination of prematurity, intestinal immaturity, microbial colonisation, and inflammatory responses. Key risk factors include:

  • Prematurity and Low Birth Weight: The underdeveloped intestine of preterm and VLBW infants is more vulnerable to injury and inflammation.
  • Enteral Feeding Practices: Although necessary for growth and development, enteral feeding can introduce pathogens and stress the immature gut, potentially triggering NEC.
  • Microbial Colonisation: Abnormal colonisation patterns of the neonatal gut have been implicated in the development of NEC, with particular bacteria and viruses identified as potential contributors.
  • Systemic Infections: Sepsis and other systemic infections can predispose infants to NEC by compromising the gut barrier and promoting inflammation.

How do we diagnose necrotising enterocolitis?

Clinical Signs:

To list all possible clinical signs of NEC would probably consume more than 500 words by itself, but let’s mention the most common ones:

Feeding difficulties are generally the prologue to the NEC narrative, followed by vomiting that is bilious or blood-stained. This is followed by increasing apnoeic episodes, escalating respiratory requirements, and temperature instability.

On examination, you might find a quiet neonate. Yes, there is such a thing, but this might be more obvious when asking the parents or nurse who knows the patient whether they have noticed a change followed by abdominal distention. When examining a patient where you suspect NEC, please remember to look at stools for any blood or mucus.

Laboratory results:

Different markers might point us in the direction of NEC, which include:

If you are reading the above and thinking, well, those are not specific to NEC, you are correct. Generally speaking, you would check the above when suspecting NEC, but the diagnosis is primarily clinical, supported by radiographic findings.

Radiographic Findings:

  1. Pneumatosis intestinalis
  2. Portal Venous gas
  3. Fixed and dilated bowel loops
  4. Abdominal free air – Pneumoperitoneum
  5. Bowel wall thickening and ileus

What is your differential diagnosis?

Differential diagnoses include septic ileus and infection causes such as sepsis, meningitis and pneumonia.

In male infants, it is always important to consider testicular torsion when presenting with abdominal concerns.

How do you treat necrotising enterocolitis?

Initial Management

Supportive Care: Initial management involves stabilising the infant, which includes fluid resuscitation, cessation of enteral feeds, and provision of total parenteral nutrition (TPN) to rest the bowel and meet the infant’s nutritional needs.

Antibiotic Therapy: Broad-spectrum antibiotics are a cornerstone of NEC treatment to combat bacterial translocation across the compromised gut barrier.

Commonly used antibiotics include a combination of ampicillin, gentamicin, and metronidazole for broad coverage against gram-positive cocci, gram-negative rods, and anaerobes, respectively.

Antibiotic therapy typically lasts 10-14 days, depending on the severity of the disease and clinical response.

I advise checking your local guidelines before prescribing antibiotics to treat NEC, as every hospital has different policies.

Advanced Pharmacological Interventions

Immunomodulatory Therapy: In severe cases where inflammation plays a significant role, immunomodulatory agents such as corticosteroids (e.g., hydrocortisone) may be considered to temper the inflammatory response. However, their use is controversial and typically reserved for select cases due to potential adverse effects.

Probiotics: Several studies have shown promise in preventing NEC by using probiotics to establish a healthy gut flora balance. Specific strains such as Lactobacillus and Bifidobacterium have been explored for their beneficial effects.

Surgical Interventions

Surgical intervention is indicated in intestinal perforation, necrosis, or failure to respond to medical management. The most common surgical procedures include:

Peritoneal Drainage: Peritoneal drainage involves inserting a catheter to drain infected fluid and relieve abdominal pressure temporarily in critically ill infants.

Resection of Necrotic Bowel: Removal of necrotic sections of the intestine is often necessary, followed by creating an ostomy (stoma) to allow intestinal healing and waste removal.

Primary Anastomosis: In selected cases, immediate reconnection of the intestinal ends (anastomosis) post-resection may be performed. This depends on the infant’s stability and the extent of healthy bowel available.

Postoperative Care of Patients with NEC

Postoperative care is critical for the recovery and long-term health of infants undergoing surgery for NEC. Key aspects include:

Monitoring for Complications: Close monitoring for signs of infection, intestinal obstruction, and failure to thrive is essential. Complications such as stricture formation or short bowel syndrome (SBS) may necessitate further interventions.

Nutritional Support: Gradual reintroduction of enteral feeding is essential, with close attention to tolerance and growth. Infants with significant bowel resection may require long-term TPN and specialized nutritional support to manage SBS.

Growth and Development Monitoring: Regular follow-up is crucial to assess developmental milestones, nutritional status, and any long-term complications associated with NEC or its treatment.

Long-term Considerations

Survivors of NEC may face long-term health issues, including growth failure, neurodevelopment delays, and gastrointestinal complications like short bowel syndrome. A multidisciplinary approach involving neonatologists, paediatric surgeons, nutritionists, and developmental specialists is essential for optimising outcomes and supporting the child and family.

Can we prevent NEC?

Preventative strategies are aimed at modulating risk factors where possible. Key measures include:

Promotion of Breast Milk: Breast milk is associated with a lower risk of NEC due to its immunological and nutritional components that support gut health and development.

Careful Advancement of Enteral Feeding: Gradual introduction and advancement of enteral feeds can help minimise the risk of NEC.

Use of Probiotics: The administration of probiotics to VLBW infants has shown promise in reducing the incidence of NEC, though the optimal strains and dosages remain under investigation.

When assessing a child for whom NEC is suspected, it’s crucial to conduct an A-E assessment, as you did, by observing the baby, reviewing the observations, and examining the history.

Look at the TUMMY! (Remember, tiny tummies, titanic troubles)

What did the nurse mean by “off”? It is always important to check the concerns of those who know the patient better than we do.

Look at the poo, is there blood? Is there mucus?

Have parents noticed anything different?

We have identified NEC when it is starting on several occasions. The most common complaint is, “The baby looks off.” The “off” is often described as a distended tummy or off colour. On one occasion, the baby being off was the baby going apnea every 30 minutes, so always remember to ask.

Identifying NEC early is important for starting treatment, but this doesn’t mean you can stop the disease. Sometimes, NEC is missed until surgical management is required.

Exploring necrotising enterocolitis (NEC) from its historical roots to modern-day challenges reveals a condition steeped in complexity and urgency. Despite advancements in neonatal care that have improved the survival rates of premature infants, NEC continues to pose a significant threat to this vulnerable population.

The detailed examination of NEC’s pathophysiology, highlighting the interplay between prematurity, intestinal immaturity, microbial colonisation, and an exaggerated inflammatory response, sheds light on the multifaceted nature of this disease. It underscores the critical need for a comprehensive approach to diagnosis and management, integrating clinical vigilance with advanced diagnostic tools to mitigate the condition’s severity and improve outcomes.

Management strategies, encompassing medical and surgical interventions, illustrate the evolution of care tailored to the severity of NEC. Broad-spectrum antibiotics, immunomodulatory therapy, and the strategic application of probiotics represent the nuanced approach required to address NEC’s underlying causes and manifestations. Though reserved for severe cases, surgical interventions highlight the advances in neonatal surgical care and the importance of postoperative management in ensuring infants’ long-term health and development.

Special thanks to Dr. Harsha Gowda for supplying the x-rays and ensuring that no nonsense was added to this article.

References

Australian and New Zealand Neonatal Network (ANZNN). (2020). ANZNN Annual Report.

Barter, B.A., & Bhatia, J. (2017). Management strategies for necrotizing enterocolitis: Integrating clinical and scientific evidence. Pediatric Clinics of North America, 64(1), 1-15.

Battersby, C., Longford, N., Mandalia, S., Costeloe, K., & Modi, N. (2017). Incidence of neonatal necrotising enterocolitis in high-income countries: a systematic review. Archives of Disease in Childhood – Fetal and Neonatal Edition, 103(2), F182-F189.

Fitzgibbons, S.C., et al. (2009). Mortality of necrotizing enterocolitis expressed by birth weight categories. Journal of Pediatric Surgery, 44(6), 1072-1076; discussion 1075-1076.

Gordon, P. V., Clark, R., & Swanson, J. R. (2014). Advances in understanding and treating NEC. Pediatrics, 133(1), 1-12.

Hunter, C.J., Upperman, J.S., Ford, H.R., & Camerini, V. (2008). Understanding the susceptibility of the premature infant to necrotizing enterocolitis (NEC). Pediatric Research, 63(2), 117-123.

Meinzen-Derr, J., Poindexter, B., Wrage, L., Morrow, A. L., Stoll, B., & Donovan, E. F. (2009). Role of human milk in extremely low birth weight infants’ risk of necrotizing enterocolitis or death. Journal of Perinatology, 2

MSD Manual Professional Version. (n.d.). Necrotizing enterocolitis. Retrieved March 13, 2024, from https://www.msdmanuals.com/professional/pediatrics/gastrointestinal-disorders-in-neonates-and-infants/necrotizing-enterocolitis

Neu, J., & Walker, W. A. (2011). Necrotizing enterocolitis. New England Journal of Medicine, 364(3), 255-264.

Author

  • Paediatric ST3, aspiring neonatologist, who loves teaching and talking. When not roaming the hospital corridors and neonatal units in the West Midlands, you'll find her in the garden or convincing her husband that they need more houseplants.

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