Overview
Definition:
Necrotizing enterocolitis (NEC) is a severe, acquired gastrointestinal emergency primarily affecting premature infants, characterized by ischemic necrosis of the intestinal wall
Surgical intervention is often required for complications like perforation, with the choice between peritoneal drainage and laparotomy being a critical decision.
Epidemiology:
NEC affects approximately 1-5% of infants born weighing less than 1500g
The incidence is higher in extremely premature infants
Risk factors include prematurity, enteral feeding, hypoxia, and bacterial colonization
Mortality rates vary significantly with severity and management, ranging from 20-50% for surgical NEC.
Clinical Significance:
NEC is a leading cause of mortality and morbidity in neonatal intensive care units
Prompt and appropriate surgical management is crucial to reduce mortality and long-term complications such as short bowel syndrome and neurodevelopmental deficits
Understanding the nuances of drainage versus laparotomy is vital for optimal patient outcomes.
Clinical Presentation
Symptoms:
Abdominal distension
Emesis, often bilious
Hematochezia or occult blood in stool
Irritable or lethargic infant
Apneic spells and bradycardia
Hypothermia or abdominal tenderness
Signs of sepsis.
Signs:
Abdominal wall erythema or induration
Palpable abdominal mass
Dilated, tense abdomen
Absent bowel sounds or diffuse tenderness
Rectal bleeding
Shock.
Diagnostic Criteria:
Modified Bell staging criteria are commonly used
Stage I: Suspected NEC
Stage II: Confirmed NEC
Stage III: Advanced NEC with perforation or instability
Radiographic findings of pneumatosis intestinalis, portal venous gas, or free air in the abdomen are key indicators for surgical intervention.
Diagnostic Approach
History Taking:
Gestational age
Birth weight
Feeding history (type, volume, advancement)
Presence of hypoxia or hypotension
Previous medical or surgical history
Family history of gastrointestinal issues.
Physical Examination:
Thorough abdominal examination, assessing for distension, tenderness, erythema, and masses
Auscultate bowel sounds
Assess vital signs, including temperature, heart rate, respiratory rate, and oxygen saturation
Assess perfusion and hydration status.
Investigations:
Abdominal radiography (plain films) in multiple views (anteroposterior, lateral, cross-table lateral) to assess for pneumatosis intestinalis, portal venous gas, dilated bowel loops, and free air
Blood tests: Complete blood count (CBC) with differential, electrolytes, blood gas analysis, lactate levels, blood cultures
Stool for occult blood.
Differential Diagnosis:
Intestinal obstruction
Malrotation with volvulus
Hirschsprung disease
Sepsis
Other causes of abdominal distension and vomiting in neonates.
Surgical Management Options
Indications For Surgery:
Clinical deterioration despite medical management
Radiographic evidence of intestinal perforation (free air)
Radiographic evidence of portal venous gas
Abdominal wall gangrene or discoloration
Persistent abdominal distension and tenderness unresponsive to medical therapy.
Peritoneal Drainage:
Indications: Primarily for localized perforation or as a temporizing measure in unstable infants where laparotomy is too high-risk
Procedure: A small incision is made, and a drain (e.g., Malecot or Foley catheter) is placed into the peritoneal cavity, usually in the right upper quadrant, to evacuate purulent fluid and intestinal contents
Benefits: Less invasive, potentially lower morbidity in select cases
Limitations: May not address extensive bowel necrosis or widespread peritonitis
Higher recurrence rate of perforation.
Laparotomy:
Indications: Widespread perforation, extensive bowel necrosis, fixed dilatation of bowel loops, hemodynamic instability not responding to initial resuscitation, or failure of peritoneal drainage
Procedure: Exploratory laparotomy with excision of necrotic bowel, creation of stomas (terminal or loop ileostomy/colostomy), and potential primary anastomosis if bowel ends are healthy
Benefits: Allows direct visualization and resection of non-viable bowel, definitive treatment
Limitations: More invasive, higher risk of complications in extremely premature and unstable infants.
Comparison Drain Vs Laparotomy:
Peritoneal drain is a temporizing measure, suitable for localized perforation in stable infants or as initial decompression in unstable patients
Laparotomy is the definitive treatment for extensive disease, perforation, or when drainage fails
Recent studies suggest that primary peritoneal drainage for NEC with perforation may be associated with a higher rate of reoperation and shorter interval to ostomy closure compared to primary laparotomy, but it can be a life-saving bridge in critically ill infants
The decision hinges on infant stability, extent of disease, and surgeon expertise.
Medical Management Before Surgery:
Bowel rest (NPO)
Nasogastric tube decompression
Broad-spectrum antibiotics
Fluid resuscitation and correction of electrolyte imbalances
Red blood cell transfusion if anemic
Vasoactive support if hemodynamically unstable
Nutritional support via total parenteral nutrition (TPN).
Postoperative Care
Medical Management Postop:
Continued bowel rest and NGT decompression
Aggressive fluid and electrolyte management
Antibiotic therapy as guided by cultures and clinical response
Pain control
Nutritional support with TPN, gradually transitioning to enteral feeds
Monitoring for recurrence of NEC or other complications.
Nursing Care:
Strict intake and output monitoring
Daily abdominal girth measurements
Meticulous stoma care
Respiratory support as needed
Close monitoring for signs of sepsis or wound infection
Early mobilization if tolerated.
Nutritional Support:
Total parenteral nutrition (TPN) is essential during the acute phase to allow bowel rest and healing
Gradual reintroduction of enteral feeds (breast milk or specialized formula) once the infant is stable and bowel sounds return
Probiotics may be considered to restore gut flora
Long-term nutritional support may be required for infants with short bowel syndrome.
Complications
Early Complications:
Intra-abdominal abscess
Sepsis
Wound dehiscence
Recurrent NEC
Short bowel syndrome
Adhesions and intestinal obstruction
Stricture formation
Necrosis of remaining bowel segments.
Late Complications:
Strictures
Adhesions leading to obstruction
Short bowel syndrome with malabsorption and failure to thrive
Neurodevelopmental delay
Increased susceptibility to infections
Biliary atresia in rare cases.
Prevention Strategies:
Minimize exposure to risk factors: gradual advancement of enteral feeds, judicious use of antibiotics, avoidance of unnecessary invasive lines, adequate oxygenation and perfusion
Early recognition and prompt surgical intervention when indicated.
Prognosis
Factors Affecting Prognosis:
Gestational age and birth weight at presentation
Severity of NEC (Bell stage)
Presence of perforation
Need for extensive bowel resection
Development of complications such as sepsis or short bowel syndrome
Hemodynamic stability
Response to treatment.
Outcomes:
Infants who undergo peritoneal drainage for localized perforation have a better prognosis than those requiring extensive resection
Survival rates for NEC treated surgically range from 60-80%, but are lower for extremely premature infants or those with extensive disease
Long-term outcomes depend on the extent of bowel loss and the development of complications like short bowel syndrome.
Follow Up:
Regular monitoring for growth and development
Nutritional assessment
Assessment for signs of intestinal obstruction or malabsorption
Serial abdominal examinations
Developmental screening and intervention programs
Close follow-up by a multidisciplinary team.
Key Points
Exam Focus:
Understand the modified Bell staging criteria for NEC
Differentiate indications for peritoneal drain versus laparotomy
Recognize complications like pneumatosis intestinalis and portal venous gas
Key surgical complications: short bowel syndrome, strictures, stoma issues
Risk factors and preventive measures are high-yield.
Clinical Pearls:
A tense, distended, erythematous abdomen in a premature infant is a surgical emergency
Consider NEC in any infant with bilious vomiting and abdominal distension
The choice between drain and laparotomy is often dictated by the infant's stability and the extent of disease
Peritoneal drain is a temporizing measure, not a definitive cure for widespread disease
Always assess for free air on lateral films.
Common Mistakes:
Delaying surgical intervention in a deteriorating infant
Incorrectly selecting peritoneal drainage for widespread bowel necrosis
Inadequate fluid resuscitation or management of shock
Failure to consider and manage complications like sepsis and short bowel syndrome
Inadequate stoma care postoperatively.