Diagnostics

• Indication: usually performed initially in newborns with abdominal distention and delayed passage of meconium

• Findings

  • Decreased or absent air in rectum

  • Dilated colon segment immediately proximal to aganglionic region

  • Distal intestinal obstruction

• Indication: usually performed in addition to x-ray, to localize and determine the length of the aganglionic segment prior to surgery

• Findings

  • Change in caliber along the affected intestinal segment (transition zone)

  • Retention of barium for 24–48 hours

• 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

• Finding

  • Absent relaxation reflex of the internal sphincter after stretching of the rectum

  • Presence of high baseline resting pressures

• Indication: confirmatory test

• Procedure

  • Full-thickness biopsy under general anesthesia

  • Suction rectal biopsy

• Findings

  • Absence of ganglion cells in an adequate tissue sample

  • Elevated acetylcholinesterase activity

  • Hyperplasia of the parasympathetic nerve fibers

  • Absent calretinin immunostained fibers#

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.