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

  1. Dilation and hypertrophy of proximal colon
  1. 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