Intussusception is a condition that occurs when a part of the intestine folds into another
section of intestines, resulting in obstruction.
This is commonly referred to as telescoping, because it’s similar to how one part of
a collapsible telescope retracts into another part.
Intussusception is the most common cause of intestinal obstruction in infants and young
children, with about two-thirds of them happening among infants under one year of age, though
adults can occasionally have intussusception too.
Now, intussusception usually happens in the ileocecal region of the intestines, which
is where the ileum of the small intestine and cecum of the large intestine meet, and
almost all intussusceptions happen when the ileum folds, or telescopes, into the cecum.
In adults, telescoping is usually caused by an abnormal growth in the intestine, like
a polyp or a tumor, which serves as a lead point or leading edge.
What happens is that the normal wave-like contractions of the intestine, called peristalsis,
grab this leading edge and pull it into the part of the bowel ahead of it.
In babies the leading edge is most often caused by lymphoid hyperplasia, or the enlargement
of lymphoid tissue.
There are a ton of tiny lymph nodes sprinkled throughout the intestines called Peyer’s
patches, and they’re particularly common in the ileum.
When a child gets some sort of viral infection in the gastrointestinal tract, usually caused
by rotavirus or norovirus, the Peyer’s patches enlarge to help fight off the infection, and
sometimes become a lead point that drags the ileum into the cecum, causing intussusception.
Intussusception can also be caused by a Meckel’s diverticulum, which is an abnormal outpouching
of gastrointestinal tissue, that sticks out of the ileum and into the peritoneal cavity.
Occasionally, the diverticulum can invert and stick back into the intestine, allowing
it to serve as a lead point that again drags the ileum into the cecum.
Although these are well known mechanisms for intussusception, the majority of cases are
considered idiopathic, meaning that they happen without a clear cause.
Risk factors include having had one previously or having a sibling with intussusception,
as well as having intestinal malrotation - which is a condition where the intestine doesn't
rotate correctly during fetal development.
Now, when an intussusception develops, the first sign is intermittent abdominal pain
that worsens with peristalsis, sometimes causing a child to guard their abdomen—for example,
they may swat away the hands of a caretaker—or draw their knees up toward the chest.
Other classic findings include vomiting, and the presence of a hard sausage-like mass in
the abdomen.
There’s also a lot of pressure on the walls of the trapped section of bowel which squeezes
shut the tiny blood vessels running in the walls, causing ischemia—or lack of blood
flow—and infarction—death of the tissues.
Ischemic and infarcted tissue results in the sloughing off of intestinal mucosal tissue,
blood, and mucus into the gut.
This can result in "red currant jelly" stool, which is a food-inspired visual for the berry
jelly consistency of the stool.
Fever isn’t usually a symptom of intussusception, but in serious cases, like with infarction,
the intestines can tear and release bacteria into the body cavity, causing sepsis and fever.
Intussusception can also prevent food or fluid from passing through the intestines, causing
an obstruction.
This can lead to a large mass in the intestines, which can potentially cause the intestine
to become twisted, a condition called volvulus.
In children, intussusception can sometimes be felt by finger while doing a digital rectal
examination, but a definite diagnosis often requires imaging techniques.
An ultrasound, X-ray or computerized tomography (or CT) scan can reveal a classic bull's-eye,
which represents the telescoped intestine shown on end, as well as signs of intestinal
obstruction.
Intussusception can develop suddenly and because of the possibility of intestinal ischemia,
rapid treatment is necessary.
A barium or air enema, can be used to unfold the intussusception, especially in children.
If it doesn’t work or if there’s a complication, then surgery may be necessary.
During surgery, the portion of the telescoped intestine is freed, any obstruction is cleared,
and any tissue that died is removed.
Alright, as a quick recap, intussusception occurs when part of the intestine slides into
an adjacent part of the intestine, a process called telescoping.
Q Intussusception can lead to intestinal obstruction and can also cut off the blood supply to that
part of the intestines, resulting in bowel ischemia.
Rapid treatment is important and can be done with a barium or an air enema, as well as
surgery, if needed.
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