The first step in diagnosing a newborn with a clinical picture of Hirschsprung disease is to obtain a contrast enema using water-soluble material. If Hirschsprung disease is suspected based on diagnostic findings, a suction rectal biopsy will be performed to confirm a diagnosis. This is a low risk procedure that can be done at the bedside or in the clinic.
Diagnosing Hirschsprung Disease in Older Children
Not every child with Hirschsprung disease will have immediate symptoms at birth. Some children begin to show symptoms as they wean off of breastfeeding or develop chronic constipation when they become toddlers. Although many children experience constipation, those with Hirschsprung disease fail to thrive, have extreme abdominal distention and sometimes depend on enemas to empty. Those with significant watery stools may have enterocolitis. Children who do not respond well to less invasive treatments such as enemas, laxatives and behavior modification, should be referred to a specialist for evaluation.
Another diagnostic technique to employ with older children is the use of anorectal manometry to look for the presence of the rectoanal inhibitory reflex (RAIR)—which is always absent in children with Hirschsprung disease. Typically the smooth muscle of the internal sphincter relaxes when stool distends the rectum. In Hirschsprung disease, the internal sphincter instead tightens worsening the obstructive symptoms. If there is an absence of a RAIR, a rectal biopsy should be performed.
In rare cases, children with Hirschsprung disease will have symptoms that include fever, abdominal distention and diarrhea due to Hirschsprung-associated enterocolitis (HAEC). HAEC can be chronic, severe and sometimes life threatening. Since constipation is usually a sign of Hirschsprung disease, children with diarrhea may not be considered for a diagnosis. It’s very important to consider the child’s history including failure to pass meconium in the first 24 hours of life as well as any past obstructive episodes.