Overview
Definition:
Hirschsprung-associated enterocolitis (HAEC) is a life-threatening inflammatory complication of Hirschsprung disease (HD), characterized by severe diarrhea, abdominal distension, and systemic toxicity
it is the most common non-surgical cause of mortality in patients with HD.
Epidemiology:
HAEC occurs in approximately 20-30% of children with Hirschsprung disease, with a higher incidence in neonates and infants
it can occur preoperatively or postoperatively, and recurrences are common.
Clinical Significance:
Early recognition and prompt management of HAEC are critical to prevent severe morbidity and mortality, including intestinal perforation, sepsis, and death
understanding risk factors and management strategies is paramount for pediatricians and pediatric surgeons preparing for DNB and NEET SS examinations.
Clinical Presentation
Symptoms:
Explosive, watery diarrhea
Abdominal distension
Vomiting, often bilious
Fever
Lethargy
Poor feeding
Rectal bleeding may be present
Signs of dehydration.
Signs:
Abdominal tenderness and guarding
Tympanitic abdomen
Palpable stool in the rectum
Rectal effluent may be foul-smelling and explosive
Signs of systemic toxicity including tachycardia and hypotension.
Diagnostic Criteria:
There are no universally accepted diagnostic criteria, but HAEC is suspected in a patient with Hirschsprung disease who develops abdominal distension, explosive diarrhea, and/or vomiting, often accompanied by systemic signs of inflammation and sepsis
a high index of suspicion is crucial.
Risk Factors And Pathogenesis
Risk Factors:
Underlying Hirschsprung disease is the primary risk factor
Other factors include delayed diagnosis of HD, inadequate surgical correction, stasis of stool proximal to the aganglionic segment, bacterial overgrowth, ischemia, and immunological factors.
Pathogenesis:
The exact pathogenesis is multifactorial, but it is thought to involve an inflammatory response to retained fecal material and bacterial toxins in the dilated, aganglionic bowel segment
impaired bowel motility and a defective mucosal barrier contribute to the inflammatory cascade.
Diagnostic Approach
History Taking:
A detailed history of HD diagnosis, surgical procedures, and onset of symptoms is vital
Assess for the presence of explosive stools, abdominal distension, vomiting, fever, and signs of dehydration
Inquire about recent antibiotic use or hospitalizations.
Physical Examination:
Thorough abdominal examination for distension, tenderness, guarding, and bowel sounds
Digital rectal examination may reveal impaction or absence of stool
however, it should be performed cautiously if perforation is suspected
Assess for signs of dehydration and sepsis.
Investigations:
Complete blood count (leukocytosis, anemia)
Electrolytes and renal function tests to assess hydration and acid-base balance
Blood cultures for sepsis
Abdominal radiography to assess distension and rule out perforation (free air)
Stool studies for infectious etiologies (e.g., C
difficile)
Contrast enema or rectal biopsy may be considered if diagnosis of HD is uncertain but typically avoided in acute HAEC.
Differential Diagnosis:
Other causes of neonatal enterocolitis (e.g., necrotizing enterocolitis in premature infants)
Sepsis
Intestinal obstruction
Gastroenteritis
Appendicitis (in older children)
Perforation from other causes.
Management
Initial Management:
Immediate bowel rest and decompression are paramount
NPO status
Nasogastric tube insertion for decompression and gastric lavage
Intravenous fluid resuscitation with electrolyte correction
Broad-spectrum intravenous antibiotics targeting gram-negative and anaerobic organisms are essential.
Rectal Irrigations:
This is a cornerstone of HAEC management
Gentle, repeated rectal irrigations with sterile saline (or sometimes antibiotic solutions) are performed to decompress the bowel and remove fecal impaction and toxins
Irrigations should be performed cautiously to avoid further injury
The frequency and volume depend on the patient's response and tolerance.
Medical Management:
Aggressive fluid and electrolyte management
Nutritional support via parenteral nutrition if prolonged NPO is required
Close monitoring of vital signs, abdominal girth, and stool output
Management of fever and pain
Serial abdominal examinations to assess for worsening signs of obstruction or peritonitis.
Surgical Management:
Surgical intervention is indicated for severe or refractory cases, suspected intestinal perforation, or evidence of ongoing ischemia
Options include exploratory laparotomy with enterostomy (diversion colostomy) to decompress the affected bowel and allow for healing, with definitive pull-through surgery at a later date once the inflammation has subsided.
Complications
Early Complications:
Intestinal perforation
Sepsis and septic shock
Bowel necrosis
Toxic megacolon
Dehydration and electrolyte imbalance
Renal failure.
Late Complications:
Recurrent HAEC
Stricture formation
Fecal incontinence
Growth failure
Adhesions and intestinal obstruction
Malabsorption.
Prevention Strategies:
Early diagnosis and definitive treatment of Hirschsprung disease
Careful postoperative care after pull-through surgery
Vigilance for early signs of HAEC in all patients with HD, especially postoperatively or in those with delayed diagnosis
Prompt initiation of rectal irrigations and bowel rest for suspected HAEC.
Prognosis
Factors Affecting Prognosis:
The severity of HAEC at presentation, promptness and effectiveness of management, presence of complications like perforation or sepsis, and the underlying status of the Hirschsprung disease (e.g., length of aganglionic segment, timing of surgery).
Outcomes:
With prompt and aggressive management, many children recover from HAEC
However, mortality can be high in severe, complicated cases
Long-term sequelae are common and require ongoing management.
Follow Up:
Close follow-up is essential after HAEC, including monitoring for recurrence, growth and nutritional status, bowel function, and surgical site
Regular assessment by a pediatric surgical and gastroenterology team is recommended.
Key Points
Exam Focus:
HAEC is a major complication of HD, characterized by fever, diarrhea, and abdominal distension
Rectal irrigations are a critical component of non-surgical management
Suspect HAEC in any child with HD presenting with acute abdominal symptoms.
Clinical Pearls:
Always maintain a high index of suspicion for HAEC in patients with Hirschsprung disease, especially if they have a history of constipation or have undergone surgery
Be aggressive with bowel decompression and fluid resuscitation
Rectal irrigations should be gentle but persistent.
Common Mistakes:
Delaying diagnosis or management of HAEC
Underestimating the severity of HAEC
Inadequate bowel decompression
Failure to administer prompt antibiotics
Performing vigorous rectal irrigations in the presence of perforation concerns
Inadequate fluid resuscitation.