Hirschsprung disease (congenital aganglionic megacolon) is an inherited disorder primarily affecting newborns. The condition is characterized by an aganglionic colon segment, usually the rectosigmoid region, which fails to relax leading to functional intestinal obstruction. The first sign of the disease is often when a newborn fails to pass meconium within 48 hours after birth and/or shows symptoms of gastrointestinal obstruction (e.g., bilious vomiting and abdominal distention). The onset and severity of symptoms vary according to the length of the aganglionic segment (a longer aganglionic segment is associated with an early and more severe onset). Diagnosis usually involves three different modalities: contrast enema, anorectal manometry, and stepwise biopsy for histological detection of aganglionosis. Treatment of choice is surgical resection of the aganglionic segment, although it is important to maintain anal sphincter function. A severe complication of the disease is Hirschsprung enterocolitis, which presents with abdominal pain, fever, and foul-smelling and/or bloody diarrhea. If not treated promptly, this condition can progress to toxic megacolon or sepsis. The prognosis for patients with Hirschsprung disease is good if treated at an early age.
- Genetic causes 
- Associated conditions 
Hirschsprung disease always involves the REcTum and is often associated with RET mutations.
- Hirschsprung disease is caused by defective caudal migration of parasympathetic neuroblasts (precursors of ganglion cells) from the neural crest to the distal colon. This process takes place between the 4th and 7th week of development.
- Affected segments are histologically characterized by the absence of the Meissner plexus and Auerbach plexus (submucosal and myenteric plexus ganglion) beginning at the anorectal line, leading to: 
- Extent of the disease 
- Delayed passage of meconium (> 48 hours)
- Distal intestinal obstruction: abdominal distention and bilious vomiting
Digital rectal examination
- Tight anal sphincter
- Empty rectum
- Squirt sign: explosive release of stool and air upon removal of the finger
- Palpation of feces via the abdominal wall
Late presentation 
Subtypes and variants
Ultrashort-segment Hirschsprung disease 
- Definition: very short segment of aganglionosis, limited to the distal rectum
- Symptoms: less severe symptoms (e.g., chronic constipation)
- Treatment: usually treated with diet and stool softeners
- Prognosis: better prognosis with fewer complications
Total colonic aganglionosis 
- Indication: usually performed initially in newborns with abdominal distention and delayed passage of meconium
- Indication: usually performed in addition to x-ray, to localize and determine the length of the aganglionic segment prior to surgery
- Change in caliber along the affected intestinal segment (transition zone)
- Retention of barium for 24–48 hours
Anorectal manometry 
- Goal: It measures the relaxation pressure of the internal anal sphincter after distention with a balloon. Difficult to perform in newborns as cooperation is essential
- Indication: : screening in atypical presentations or in older children
- Absent relaxation reflex of the internal sphincter after stretching of the rectum
- Presence of high baseline resting pressures
Rectal biopsy 
- Indication: confirmatory test
In approximately 10% of newborns with Hirschsprung disease, no dilation or change in caliber is found in the colon contrast enema examination. Imaging and rectal biopsy are necessary to confirm the diagnosis.
Surgical correction 
- Objective: definitive treatment to remove the affected segment of the colon and bring the normal ganglionic intestinal ends together
- Total transanal endorectal pull-through: preferred method that can be done in one stage 
- Abdominoperineal pull-through (Soave procedure): traditionally performed in two stages:
- First stage: diverting colostomy to relieve the dilated bowel .
- Second stage
Medical therapy 
- Maintain normal fluid and electrolyte balance
- Reduction of bowel distention
- Prevent and manage complications
- Initial medical management
- Postoperative medical management
|Differential diagnosis of intestinal obstruction in neonates|
|Hirschsprung disease||Intestinal neuronal dysplasia (IND) ||Meconium ileus||Meconium plug syndrome||Congenital hypothyroidism|
|Clinical features|| |
|Diagnosis|| || || |
The differential diagnoses listed here are not exhaustive.
Hirschsprung-associated enterocolitis 
- Symptoms of toxic megacolon (e.g., abdominal pain, fever, foul-smelling and/or bloody diarrhea)
- If not treated early, sepsis, transmural intestinal necrosis, and perforation are possible.
- Management: IV fluid resuscitation, broad-spectrum IV antibiotics (anaerobic and aerobic coverage), rectal irrigations, with possible colostomy
- Fecal incontinence
- Urinary dysfunction
- Erectile dysfunction
- Peritonitis due to bowel perforation
We list the most important complications. The selection is not exhaustive.
- Good prognosis with early treatment 
- Higher mortality associated with younger age, length of aganglionosis, and preoperative enterocolitis