Introduction

NEC, or necrotizing enterocolitis, is characterized by intestinal tissue death. It mostly affects premature newborns and happens when the intestinal wall's lining dies and the tissue peels off. The exact cause for this illness is not yet known; however, it is believed to be due to a reduction in blood flow to the intestines, which prevents the gut from creating the mucus that shields the gastrointestinal system. Intestinal bacteria could also be responsible for the development of NEC.¹ 

Poor feeding, vomiting, lethargy, and abdominal discomfort are nonspecific signs and symptoms of NEC; thus, when these symptoms are seen in the neonatal population, clinicians should be cautious. The results of a physical examination in a baby with NEC may show a palpable abdominal mass, visible bowel l loops, decreased bowel sounds, abdominal distention, abdominal pain to touch, and abdominal wall redness. Respiratory failure, circulatory collapse and reduced peripheral perfusion evidenced by low blood pressure and high heart rate are examples of systemic findings.²

Because of its high rate of morbidity and mortality, NEC continues to be at the center of debate on the precise indications for surgical care of the condition. Finding pre-operative variables such as the growth, gestational age and other medical conditions of the baby, assessing whether surgery is better than medical therapy, and determining the particular kind of surgery that offers the most therapeutic benefit are all contentious issues.³

Pathophysiology and risk factors of NEC

About 7% of babies weighing between 500 and 1500 g at birth go on to develop NEC.⁴ It can be fatal in up to 50% of babies. Intestinal inflammation is a hallmark of pathophysiology, which can lead to multiorgan failure, widespread infection/inflammation, and death. 

When seen closely, the bowel in NEC appears enlarged with evidence of bleeding. Examination under the microscope will show cell death due to blood loss, formation of gas bubbles beneath the gut surface, bacterial overgrowth, epithelial regeneration, mucosal edema, and inflammation.⁵ As NEC worsens, intestinal perforation may result, which could result in sepsis(severe infection with an extreme reaction to it by the body’s immune system), peritonitis (inflammation of the tissue lining the abdomen), and even death.²

In addition to being premature other l risk factors for necrotizing enterocolitis include:

• Premature rupture of the membranes associated with amnionitis (infection of the membranes of the water sac)
• Asphyxia during birth
• Being small for the gestational age
• Congenital heart disease 
• Anemia
• Transfusions and blood exchange
• Dysbiosis, or alteration of the intestinal microbiome
• Consumption of milk other than breast milk

There are typically three digestive factors:

• An insult that resulted in disruption of blood flow to the gut 
• The colonization of bacteria
• Feeding via mouth⁶

Treatment 

The degree of severity of the disease determines the course of treatment for NEC. Accordingly, NEC is divided into 3 stages.

For patients in stage 1(suspected NEC), treatment consists of intensive supportive care, feeding through an intravenous tube with delivery of nutrients directly into the bloodstream rather than via the mouth to relax the intestines, and ongoing diagnostic and monitoring tests to make sure the illness is not becoming worse. 

Patients in stage 2 (mild to moderate NEC) are treated with antibiotics and the continuation of stage 1 therapies. Some patients in stage 3 (Advanced NEC) may need emergency surgery. Many babies recover from treatment in as little as 72 hours, and doctors may choose to resume regular feedings. Surgery might be required, though, if the illness worsens or a hole forms in the colon or bowel.⁷

Medical (non-surgical) management of NEC 

Medical stabilization continues to be the cornerstone of treatment after a clinical diagnosis of NEC. Usually, a protocol is used that includes antibiotics, feeding delivered directly into the bloodstream, gastric decompression, and bowel rest. 

The main antibiotics used in treating NEC are clindamycin, gentamicin, and ampicillin. 

Vancomycin may be used in place of ampicillin in certain situations. Nonetheless, trends of local resistance should inform the selection of antibiotics. Antibiotics administered via the oral route are not advised. It is also advised to promptly treat any bleeding or electrolyte abnormalities.

Within 72 hours, many newborns respond well to treatment, and doctors may choose to resume regular feedings (in general, newborns with proven NEC are not fed for at least two weeks). However, surgery may be required if the problem worsens or a hole forms in the gut or intestine.⁹

Surgical management of NEC 

The goal of surgery is to remove the dead bowel while minimizing intestinal length loss. The ideal window for surgery is after bowel death has occured but before perforation of bowel or spread of infection. Unfortunately, there is no combination of clinical presentation, lab values, or radiographic findings that accurately identifies this stage. The only absolute indication for surgery is the presence of gas within the abdominal cavity also called pneumoperitoneum, but this is only present after perforation has already occurred.¹⁰

Laparotomy

A laparotomy involves removing the segment of dead or perforated bowel and reconstructing the continuation of bowel while preserving intestinal length.¹⁰

Primary Peritoneal Drainage (PPD)

It is performed at the bedside with local anesthesia and is reserved for critically ill infants with very low birth weight who are not stable for laparotomy. A Penrose drain is inserted into the peritoneal cavity through the lower abdomen and saline irrigation is done to remove abdominal contents. 

Infants who continue to deteriorate or develop signs of persistent intestinal obstruction after initial PPD will have to undergo laparotomy subsequently. Only 30% of babies who undergo peritoneal drainage require no further surgical intervention.¹⁰

When is surgery necessary? Clinical decision-making criteria

Surgical therapy may not provide any further therapeutic benefit for babies with NEC with no perforation. In such cases, conservative management through the means of broad-spectrum antibiotics, with the addition of metronidazole, results in equally favorable outcomes while preventing the complications that are routinely associated with surgical interventions.¹¹

Currently, intestinal perforation remains the only absolute indication for laparotomy.⁹ Other relative indications for surgery include clinical deterioration despite medical management, gas in the veins draining intestines, fluid within the abdominal cavity fixed intestinal loop as seen on radiographs, palpable abdominal mass, redness of the abdominal wall, and low platelet count.

Prognosis

The prognosis is determined by how severe the illness is, and when it is identified and treated. The overall mortality rate is between 10% and 50%. Nonetheless, the mortality rate for newborns with severe necrotizing enterocolitis,with full-thickness breakdown of the gut wall and complications such as perforation and peritonitis, is almost 100%.¹¹ 

Factors Influencing Prognosis

The overall prognosis can be affected by a number of circumstances such as:

• Early diagnosis: Results can be greatly enhanced by early detection and treatment.
• Overall health of the infant: Prognoses are generally better for infants with fewer underlying medical conditions.
• Adherence to treatment: Recovery depends on patients following their doctors' recommendations and treatment regimens.¹²

Complications

Complications vary from one newborn to another and within different stages of the disease.

Short-term complications are:

• Complications from infection: Abscess development, infection of the nervous system, infection of lining of abdomen and widespread infection with sepsis
• Blood clotting abnormalities
• Issues with the heart and lungs
• Electrolyte abnormalities 
• Hypoglycemia

Long-term complications are: 

• Narrowing of the gastrointestinal tract due to adhesions and strictures
• Obstructed bile flow 
• Intestinal insufficiency and/or short bowel syndrome
• Growth failure¹³

Prevention

There appears to be some protection against necrotizing enterocolitis when premature babies are fed their mother's breast milk instead of formula. Hospital staff also take precautions to keep the baby's blood oxygen levels from falling too low and refrain from giving the baby extremely concentrated formula. Additionally, if at all possible, the newborn should not be given antibiotics or acid-suppressing drugs. Probiotics, or beneficial bacteria, have shown some promise in prevention; however, this treatment is still in the experimental stage. Corticosteroids may be administered to pregnant women who are at risk of preterm delivery in order to help avoid necrotizing enterocolitis.¹⁴

FAQs

How does surgical NEC impact long-term neurodevelopment compared to medical NEC?

Compared to infants treated medically, those who have surgery for NEC typically have lower neurodevelopmental outcomes. This is probably because of

• Increased inflammation throughout the body
• Extended hospital stays and delays in feeding
• Increased usage of antibiotics
• Increased sepsis rates

Early intervention therapies and neurodevelopmental evaluations are frequently part of follow-up care.

Can a baby recover fully from NEC without needing surgery?

Indeed, a lot of infants can fully recover with just medical care, particularly those with mild to severe NEC who are discovered early. Stopping feeding via the oral route, administering fluids and medicines directly into the bloodstream, and careful observation are all part of this. Surgery might not be required at all if the bowel does not become necrotic or perforated.

Even in patients that get medical treatment, long-term monitoring is necessary to monitor for potential development of intestinal strictures that can block the bowel, growth delays, or feeding problems.

Summary

Necrotizing enterocolitis (NEC) is a dangerous condition in which the gut tissue becomes inflamed and begins to decompose. Although there is no proven cure, supportive care is given to reduce the inflammatory response that characterizes this illness NEC continues to be a major cause of morbidity and mortality in preterm newborns, and treatment approaches have not been much enhanced in decades. Supportive therapy alone may be sufficient for moderate, non-progressive NEC, but 50% of newborns with NEC have severe, progressive disease that necessitates immediate surgery.¹⁰