Hirschsprung disease is when a baby is born with intestines that can’t move stool out
of the body.
This is because part of the intestine is missing its nerve cells, called ganglion cells, which
keeps the intestine from working normally.
Hirschsprung disease is fairly common, affecting about 1 in 5,000, and is more common in boys
than girls.
About 20% of cases occur within families, so it may be genetic.
As a baby grows, ganglion cells migrate down the small intestine
and colon.
These ganglion cells trigger a series of contractions and expansions, called “peristalsis”,
that help move food through the intestines.
But in Hirschsprung disease, the ganglion cells don’t migrate down all the way, leaving
an area without any ganglion cells, which is called an “aganglionic” area.
This has two effects: First, the aganglionic area, and the anal canal, are unable to relax.
This means that they are much stronger than they should be, and create a high amount of
pressure.
And second, the peristalsis in the healthy area can’t overcome this pressure to move
stool out of the body.
Usually, this only affects the lower end of the colon.
But in rare cases, it can affect the whole colon, or in extreme cases, even the small
intestine.
After the baby is born, stool starts to build up, and the stomach may become very large.
The colon responds by becoming swollen and painful, which is called “colitis.”
This leads to the following cycle: First, the aganglionic colon and the anal canal become
blocked.
Next, stool and gas build up.
This allows bacteria to grow to abnormal levels.
This makes the colon flare up, known as colitis, becoming painful and swollen, and can’t
absorb as much water and nutrients.
This further weakens the healthy colon, which puts less pressure on the anal canal, which
continues the cycle.
Symptoms of this cycle include: decreased peristalsis, an enlarged abdomen, liquid stool,
fever, dehydration, abdominal pain, nausea, vomiting, and stunted growth.
The first and most effective way to treat colitis is by a “colorectal irrigation,”
which clears the colon out with water.
This breaks the cycle and allows the baby to recover from Colitis before surgery.
Even though irrigations can help manage Colitis, Hirschsprung disease is life-threatening if
left untreated, and must be fixed by surgery.
The goal of the surgery is to un-block the colon, and preserve bowel control.
This is done by removing the aganglionic area while protecting the anal canal.
The first cut is made just beyond the affected area.
This includes the “rectosigmoid,” the body’s natural reservoir for stool.
Without this reservoir, bowel movements may be faster than they normally would be.
Next, the second cut is made in the rectum, just above the anal canal.
It is critical that this cut is made 2cm above an area called the “pectinate zone.”
If cuts are made through this zone, it can damage the anal canal.
This can result in “fecal incontinence,” and the child will not be able to control
their bowel movements.
Since fecal incontinence is irreparable, irreversible, but most importantly, preventable, it is critical
that surgeons protect the anal canal.
After this cut, the aganglionic area is removed.
Finally, the healthy intestine is connected to the rectum, restoring peristalsis.
Even if the procedure is done correctly, 30% of patients will still have flare ups of colitis.
This is because the anal canal is still stronger than the healthy colon at first.
Irrigations are still needed to stop stool from building up until the healthy colon gets
strong enough to overcome the pressure of the anal canal.
This can take months to even years, and varies widely from person to person, but the severity
and frequency of colitis, and irrigations, should decrease as your child grows.
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