Hirschsprung's disease
Definition
Absence of ganglion cells in the distal bowel, extending proximally
Incidence
A. Estimated incidence: 1 in 5,000 live births
B. Male predominance: 4:1 ratio; 1.5-2:1 in long-segment HD
Pathology
Gross
- Dilation and hypertrophy of proximal colon
- Abrupt or gradual transition to narrow distal bowel
Segments
Dilated ganglionic segment
Transitional zone (hypoganglionic)
Narrow aganglionic segments
Embryology
A. Developmental Timeline
Appearance of neural crest-derived neuroblasts in developing esophagus (5 weeks)
Migration to the anal canal (5th to 12th weeks of gestation)
B. Neural Crest Cell Migration
Craniocaudal direction
Failure of migration leading to aganglionic segment in HD
C. Genetic Factors
Implications in HD etiology
Down syndrome as the most common chromosomal abnormality
Clinical picture
Histo
Absence of Ganglionic Cells
Myenteric (Auerbach's) plexus
Submucous (Meissner's) plexus
Presence of Hypertrophied Nerve Trunks
Non-myelinated
Space normally occupied by ganglionic cells
Aganglionic Segment Distribution
Anorectal region to proximal extension
Variations in affected segments
Localization of Aganglionosis
Rectosigmoid Region (75% of cases)
Sigmoid, Splenic Flexure, or Transverse Colon (17%)
Total Colon with Short Segment of Terminal Ileum (8%)
Extremely Rare Cases
Involvement of both small and large intestine
A. Symptoms
Neonatal Intestinal Obstruction
Failure to pass meconium in the first 24 hours
Explosive evacuation of gas and foul-smelling stools upon rectal examination
Chronic Progressive Constipation in Older Children
Persistent constipation and chronic abdominal distension
B. Neonatal Presentation
Failure to Pass Meconium
Over 90% fail to pass meconium in the first 24 hours
Normal meconium passage within 24 hours after birth in healthy full-term babies
Passage within 48 hours in all healthy full-term babies
Additional Symptoms
Constipation, abdominal distension, vomiting during the first few days of life
Explosive evacuation of gas and foul-smelling stools upon rectal examination or introduction of a rectal tube
C. Enterocolitis and Complications
Diarrhea in About 30% of Cases
Suggestive of enterocolitis
Progression to Toxic Megacolon
Sudden onset of marked abdominal distension
Bile-stained vomiting, fever, signs of dehydration, sepsis, and shock
D. Diagnostic Clues
Abdominal Distension
May be present in both neonates and older children
Delayed Passage of Meconium
Key indicator in neonates
Rectal Examination
Explosive evacuation of gas and foul-smelling stools
Presentation with Diarrhea
Suggestive of enterocolitis and potential progression to toxic megacolon
E. Age-Related Symptoms
Neonates
Emphasis on meconium passage and early signs of obstruction
Older Children
Persistent constipation and abdominal distension
Diagnosis
A. Abdominal X-ray
Findings
Dilated loops of bowel with fluid levels and airless pelvis
Presence of air in the bowel wall may suggest enterocolitis
Pneumoperitoneum possible in cases of perforation
Key Considerations
Essential imaging for initial assessment
B. Contrast Enema
Procedure Details
Conducted without bowel preparation to preserve transitional zone
Typical HD case shows barium flow from undilated rectum through a cone-shaped transitional zone into dilated sigmoid colon
Reversed recto-sigmoid index (<1) compared to normal (>1)
Delayed film at 24 hours may confirm diagnosis by demonstrating retained barium
Significance
Confirmatory diagnostic tool, especially revealing the characteristic transition zone
C. Anorectal Manometry
Normal Response
Distending the rectal balloon with air elicits recto-anal inhibitory reflex (RAIR)
Immediate transient rise in pressure and simultaneous depression of pressure in the internal sphincter
HD Response
Complete absence of internal sphincter relaxation, i.e., absent RAIR
Role in Diagnosis
Provides functional insights supporting the diagnosis of HD
D. Rectal Biopsy
Procedure Variants
Suction biopsy in neonates (safe, painless, bedside procedure)
Full-thickness open biopsy in older children for more tissue and deeper levels
Site Considerations
Biopsy site at least 0.6 in. (1.5 cm) above the dentate line
Distal rectum normally lacks ganglion cells
Histological Confirmation
Absence of Meissner and Auerbach's ganglion plexuses
Marked hypertrophy of nerve trunks supporting HD diagnosis
Essential for definitive confirmation of HD + important medico-legal
Management
A. Traditional Approach
Colostomy at Diagnosis
Creation of a diverting colostomy
Timing: At the time of diagnosis
Purpose: Temporary diversion to alleviate symptoms
Definitive Pull-Through Procedure
Timing: Once the child grows and weighs more than 10 kg
Procedure: Surgical correction to remove aganglionic segment
B. Modern Approaches
One-Stage Pull-Through Operations in Newborns
Procedure performed without diverting colostomy
Management: Regular rectal washouts and suppositories
Timing: Surgery conducted few months later as the child grows
Minimally Invasive Laparoscopic Techniques
Variety of procedures applicable
Advantages: Reduced invasiveness, quicker recovery
Transanal Endorectal Pull-Through Operation
Procedure performed without opening the abdomen
Application: Particularly effective in rectosigmoid HD
Outcomes: Demonstrates excellent results
C. Enterocolitis Complications
Correction of Dehydration and Electrolyte Imbalance
Achieved through appropriate fluid infusion
Bowel Decompression
Essential for babies with life-threatening complications
Techniques: Rectal irrigations or life-saving colostomy if necessary
D. Visualization Techniques
Abdominal X-ray Monitoring
Essential for postoperative follow-up
Identifying complications: Wound infections, anastomotic leak, strictures, necrosis, ileus
Long-Term Surveillance
Monitoring for late complications: Constipation, enterocolitis, incontinence, anastomotic problems, adhesive bowel obstruction, urogenital complications
Definitive surgical procedure
A. Swenson's Pullthrough
Procedure Steps
Removal of all aganglionic bowel up to 1 cm from the dentate line posteriorly
Anastomosis: Colo-anal anastomosis from the outside
Considerations
Preservation of a margin of healthy tissue to ensure optimal function
Key in addressing the aganglionic segment
B. Duhamel's Pullthrough
Procedure Steps
Dissection behind the rectum (to minimize pelvic nerve damage) to create a tunnel
Anastomosis: Ganglionic bowel brought through approximately 1 cm above the dentate line, creating a side-to-side anastomosis using a stapler
Rationale
Emphasizes minimizing pelvic nerve damage
Use of stapler for precise and secure anastomosis
C. Soave's Pullthrough
Procedure Steps
Continuation of colon dissection in the submucosal plane to approximately 1 cm from the dentate line at the pelvic reflection
Anastomosis: Ganglionic bowel pulled through the rectal muscle sleeve, anastomosed to anal mucosa
Unique Feature
Extramucosal dissection to create anastomosis
Effective in rectosigmoid HD
Complication
A. Early Postoperative Complications
Wound infections, anastomotic leak, stricture, necrosis
Intestinal adhesions, ileus
B. Late Complications
Constipation, enterocolitis, incontinence
Anastomotic problems, adhesive bowel obstruction
Urogenital complications