Hirschsprung's disease

Diagnostic Imaging of Hirschsprung's Disease

To confirm the diagnosis, radiography using a contrast enema is performed. When evaluating the obtained images in the supine position, several key signs are noted.

In the lateral projection, a reversed rectosigmoid ratio (reversed rectosigmoid ratio) is visualized. The sigmoid colon itself appears shortened, and the rectal wall is characterized by irregularity and narrowing.

In the anteroposterior projection, the most significant sign is an abrupt change in large bowel caliber (abrupt calibre change). This diameter transition is localized at the junction of the descending and sigmoid colon. The described radiological findings classically correspond to short-segment Hirschsprung's disease (short-segment Hirschsprung disease).

Bowel Obstruction Syndromes: Common Features

The terms "small left colon syndrome" and "meconium plug syndrome" may be used as synonyms in clinical practice, yet they have fundamental pathogenetic differences. Both conditions clinically manifest with symptoms of acute bowel obstruction (bowel obstruction) and a marked delay in the passage of initial stool—meconium.

On a plain abdominal radiograph, both conditions will show a similar pattern: marked distension of both small and large bowel loops extending strictly up to the level where thickened meconium plugs are located.

Small Left Colon Syndrome

Also known as functional immaturity of the colon (Functional Immaturity of the Colon).

• Etiology and Risks: It is based on transient (temporary) functional obstruction caused by immaturity of the myenteric plexus (myenteric plexus). The condition develops much more frequently in newborns whose mothers have diabetes mellitus or a history of substance abuse.
• Contrast Findings: A microcolon (microcolon) forms distal to the splenic flexure (splenic flexure). There is an abrupt transition from the narrowed segment to a moderately dilated proximal portion of the colon. Unlike Hirschsprung's disease, the rectosigmoid ratio remains within normal limits.
• Differential Diagnosis: It is important to distinguish it from the long-segment form of Hirschsprung's disease. If clinical symptoms do not resolve, the patient is indicated for a biopsy to definitively verify the diagnosis.

Meconium Plug Syndrome

This condition (Meconium plug syndrome) represents a temporary obstruction of the colonic lumen by dense masses of meconium.

• Clinical Associations: The syndrome may be associated with cystic fibrosis (cystic fibrosis - CF) and Hirschsprung's disease, so both of these severe disorders must be specifically ruled out. An increased incidence of the syndrome in premature infants and in infants born to mothers receiving magnesium sulfate therapy is also discussed (though the latter factor is considered controversial).
• Enema Radiography: Meconium plugs are most commonly found in the region of the splenic flexure, and the bowel is dilated proximal to this level. Unlike the previous syndrome, the formation of a microcolon is entirely uncharacteristic here.
• Treatment: A water-soluble contrast enema (water-soluble contrast enema) serves both a diagnostic and a therapeutic function. Following the successful passage of meconium plugs, the symptoms of mechanical obstruction resolve completely.

Meconium ileus

Meconium ileus (Meconium Ileus) is another form of distal bowel obstruction. Its direct cause is dense, thick masses of thickened meconium that block the lumen in the terminal ileum (terminal ileum). Thick meconium begins to be produced in such infants during the prenatal period.

There is an extremely close association between this condition and cystic fibrosis (CF):

1. About 80–90% of infants diagnosed with meconium ileus have cystic fibrosis.
2. In 10–20% of all patients with cystic fibrosis, meconium ileus is the very first clinical manifestation of the disease.
3. Genetically, the pathology is characterized by an increased prevalence in children with the ΔF508 mutation (especially regarding homozygotes for this mutation).

Despite the seriousness of the diagnosis, in more than half of affected infants, the clinical course is characterized as uncomplicated (simple) meconium ileus.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Histological features of the long-segment form of Hirschsprung's disease
• Mechanism of the effect of myenteric plexus immaturity on bowel motility
• The role of the ΔF508 mutation in altering prenatal meconium properties
• Specifics of using water-soluble contrast agents in newborns
• Algorithm for ruling out cystic fibrosis in neonatal bowel obstruction

Other Topics in "Pediatric Diagnostic Radiology"

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