How should I evaluate and manage an adult with chronic refractory constipation, abdominal distension, and delayed evacuation suggestive of Hirschsprung disease?

Adult-Onset Hirschsprung Disease: Evaluation and Management

In adults presenting with lifelong refractory constipation, abdominal distension, and delayed evacuation, you must obtain a contrast enema looking for a transition zone with rectosigmoid index <1, perform rectal biopsy to confirm absent ganglion cells, and proceed with surgical resection of the aganglionic segment as definitive treatment. 1, 2, 3

Clinical Recognition

Pathognomonic Physical Examination Finding

• The "gush sign" on digital rectal examination is pathognomonic: when your examining finger passes through a stenotic/spastic rectal segment, there is a sudden release of accumulated liquid stool and gas from the dilated proximal colon 1
• Assess for visible peristaltic waves on the abdominal wall, which indicate proximal obstruction 1
• Document sphincter tone and degree of abdominal distension 1

Essential Historical Features

• Delayed passage of meconium at birth (though this history may be unknown or forgotten in adults) 2, 4
• Chronic constipation requiring enemas since early childhood, not just adult-onset symptoms 2, 4, 3
• Family history of Hirschsprung disease should raise suspicion 4
• Rule out endemic area exposure for Chagas disease, which causes acquired megacolon through myenteric plexus destruction by Trypanosoma cruzi 1

Diagnostic Algorithm

Step 1: Exclude Mechanical Obstruction and Mimics

• Obtain CT abdomen/pelvis with IV contrast to exclude mechanical obstruction, looking specifically for a distinct transition point (which suggests true obstruction rather than pseudo-obstruction) 5
• Review all medications: opioids and anticholinergics (especially cyclizine) must be discontinued or minimized as they cause pseudo-obstruction that mimics Hirschsprung disease 6
• Screen for hypothyroidism, diabetes, and coeliac disease 6
• Consider Chagas serologies if the patient has lived in or traveled to Latin America 1

Step 2: Confirm Hirschsprung Disease

• Contrast enema (barium or water-soluble) is the first-line imaging study: look for a narrowed distal rectum with dilated proximal sigmoid colon creating a "cone-shaped transition zone" and calculate the rectosigmoid index (should be <1 in Hirschsprung disease) 2, 3
• Rectal suction biopsy or full-thickness biopsy is mandatory for diagnosis: histopathology must demonstrate absent ganglion cells in both Meissner's (submucosal) and Auerbach's (myenteric) plexuses 3, 7
• Anorectal manometry shows absent rectoanal inhibitory reflex (failure of internal anal sphincter to relax with rectal distension), though this may be difficult to perform in severely impacted patients 7

Step 3: Define Disease Extent

• Adult Hirschsprung disease typically involves ultrashort or short segments (rectum to sigmoid), which explains why these patients survived to adulthood with relatively mild symptoms 3, 7
• However, total colonic aganglionosis with ileal extension can occur and carries higher morbidity and mortality 4
• Intraoperative assessment during surgery will define the proximal extent of aganglionic bowel 4

Management Strategy

Acute Presentation with Obstruction

• If the patient presents with acute bowel obstruction, perform urgent diverting colostomy to decompress the bowel and prevent perforation 2, 4
• Resuscitate with IV crystalloids and correct electrolyte abnormalities 8
• Insert Foley catheter to monitor urine output (chronic megacolon can cause obstructive uropathy) 9
• Manually disimpact if fecal impaction is present 7

Definitive Surgical Treatment

• Surgical resection of the aganglionic segment is the only definitive treatment 3, 7
• For ultrashort/short segment disease: transanal endorectal pull-through with delayed coloanal anastomosis provides excellent functional outcomes with resolution of constipation and preserved continence 2
• For long-segment or total colonic aganglionosis: total abdominal colectomy with end ileostomy is required, with possible future reconstruction depending on ileal involvement 4
• Optimize nutritional status before definitive surgery if the patient is malnourished (BMI <18.5 or >10% weight loss) 6

Surgical Timing

• In stable patients with colostomy: perform definitive pull-through procedure after 3-6 months once inflammation resolves and nutritional status improves 2
• In patients without acute obstruction: proceed directly to definitive resection if nutritional status is adequate 7

Critical Pitfalls to Avoid

Misdiagnosis as Functional Constipation

• Adult Hirschsprung disease is frequently misdiagnosed as chronic idiopathic constipation until a catastrophic complication (volvulus, perforation, toxic megacolon) occurs 9, 4
• Any adult with constipation since early childhood warrants investigation for Hirschsprung disease, not empiric laxative therapy 3

Confounding Factors That Obscure Diagnosis

• Severe malnutrition itself impairs gut motility and can mimic or worsen dysmotility 6
• Long-term opioid use causes narcotic bowel syndrome; consider supervised opioid withdrawal with pain specialist involvement before attributing all symptoms to Hirschsprung disease 6
• Eating disorders must be excluded as they cause similar radiological and clinical findings 6

Inadequate Biopsy Technique

• Superficial mucosal biopsies are insufficient; suction biopsy must include submucosa to visualize Meissner's plexus, or full-thickness biopsy is required 3, 7
• Biopsies taken too distally (within 2 cm of dentate line) may show physiologic hypoganglionosis and give false-positive results 7

Surgical Complications

• Megarectum with chronic fecal impaction increases risk of anastomotic complications; thorough bowel preparation and disimpaction are essential 9
• In total colonic aganglionosis with ileal extension >50 cm, primary reconstruction carries high morbidity; permanent ileostomy is safer 4

Multidisciplinary Team Requirements

• Gastroenterologist for endoscopy and biopsy 6
• Colorectal surgeon experienced in pull-through procedures 2
• Gastrointestinal pathologist for specialized histopathology 6
• Dietitian for nutritional optimization 6
• Pain specialist if chronic opioid use is present 6