Note: All links within content go to MayoClinic.com

Intussusception is a rare but serious disorder in which part of the intestine — either the small intestine or colon — slides into another part of the intestine. This "telescoping" often blocks the intestine, preventing food or fluid from passing through. Intussusception also cuts off the blood supply to the part of the intestine that's affected.

Intussusception is the most common cause of intestinal obstruction among children. Intussusception is rare in adults. Most cases of adult intussusception are the result of an underlying medical condition. In contrast, most cases in children have no known cause.

Emergency medical care is required to treat intussusception to avoid severe dehydration and shock, as well as prevent infection that can occur when a portion of intestine dies due to lack of blood. With prompt attention, intussusception can often be successfully treated without lasting problems.

Children
Signs and symptoms of intussusception in children include:

• Severe abdominal pain that comes and goes (intermittent pain)
• Stool mixed with blood and mucus (sometimes referred to as "currant jelly" stool because of its appearance)
• A lump in the abdomen
• Swollen (distended) abdomen
• Vomiting
• Diarrhea
• Fever
• Dehydration
• Lethargy

The first sign of intussusception in infants is usually sudden, loud crying caused by abdominal pain. Infants who have abdominal pain may pull their knees to their chest when they cry. The pain of intussusception comes and goes, usually every 15 to 20 minutes at first. These painful episodes last longer and happen more often as time passes.

Adults
Although rare, intussusception can happen in adults. Signs and symptoms of intussusception in adults may last a long time (chronic symptoms), or they may come and go (intermittent symptoms). They may include:

• Changes in bowel movement frequency
• The urge to have a bowel movement immediately (urgency)
• Rectal bleeding
• Crampy abdominal pain
• Pain in one area of the abdomen
• Swollen (distended) abdomen
• Nausea
• Vomiting

Your intestine is shaped like a long tube. Intussusception is a disorder in which one part of the intestine — usually the small intestine — slides inside another part. This is sometimes referred to as "telescoping" because it's similar to the way a collapsible telescope folds together. Intussusception is much more common in children, particularly in infants younger than 1 year, than in adults.

Some medical conditions may cause intussusception. But, in many cases, doctors can't determine the exact cause. The older you are when you develop intussusception, the more likely it is that an underlying medical condition is causing the problem.

Children
For most cases of intussusception in children, the cause is unknown. Viral infection or a growth in the intestine, such as a polyp, lymph node or tumor, may trigger it. In the past, some cases of intussusception seemed to be associated with a version of the rotavirus vaccine. Rotavirus is a childhood illness that causes severe diarrhea, vomiting, fever and dehydration. That vaccine was removed from the market in 1999. There's no evidence that the rotavirus vaccine currently available (RotaTeq) causes intussusception.

Adults
In adults, the cause of intussusception may be:

• Noncancerous (benign) or cancerous (malignant) growths
• Scar-like tissue in the intestine (adhesions)
• Surgical scars in the small intestine or colon
• Problems with the movement of food through the digestive tract (motility disorders, such as irritable bowel syndrome, gastroparesis and Hirschsprung's disease)
• Long-term (chronic) diarrhea

Children are much more likely to develop intussusception than adults are. It's the most common cause of bowel obstruction in children between the ages of 3 months and 5 years, with the majority of cases occurring among children younger than 1 year. Intussusception affects boys more often than girls (a ratio of 3-to-2). Malrotation, a condition present at birth (congenital) in which the intestine doesn't develop correctly, is also a risk factor for intussusception. Once you have had intussusception, you're at increased risk to develop it again.

Intussusception requires emergency medical care. If your child develops the following signs or symptoms, seek medical help right away:

• Severe abdominal pain that comes and goes (intermittent pain). Infants who have abdominal pain may pull their knees to their chest and cry. Between bouts of pain, your child may appear normal and comfortable, only to have pain again later.
• Stool mixed with blood and mucus (sometimes referred to as "currant jelly" stool because of its appearance).
• A lump in the abdomen.
• Swollen (distended) abdomen.
• Vomiting.
• Diarrhea.
• Fever.
• Dehydration.
• Lethargy.

Your child's doctor will ask about symptoms and do a physical exam to assess your child's medical situation. The doctor may suspect intussusception, or another type of intestinal obstruction, if your child has a lump in the abdomen, along with intermittent pain or inconsolable crying. Your child's doctor may order blood and urine tests, as well as a fecal occult blood test, which checks for blood in the stool.

To confirm a diagnosis of intussusception, your child's doctor may recommend several tests, including the following:

• X-ray or other abdominal imaging. Taking images of your child's abdomen with X-ray, ultrasound or computerized tomography (CT) scans may reveal intestinal obstruction caused by intussusception. Abdominal imaging also can show if the intestine has been torn (perforated).
• Barium or air enema. A barium enema is basically a colon X-ray. During the exam, the doctor will insert liquid barium — or in some cases air — into your child's colon through the rectum. This makes the pictures on the X-ray clearer. Sometimes a barium or air enema will correct intussusception, and no further treatment is needed. A barium enema can't be used if the intestine is torn.

Intussusception can cut off the blood supply to the affected portion of the intestine. If left untreated, lack of blood causes tissue of the intestinal wall to die. Tissue death can result in a tear (perforation) in the intestinal wall, which can lead to peritonitis, an infection of the lining of your child's abdominal cavity.

Peritonitis is a life-threatening condition that requires immediate medical attention. Signs and symptoms of peritonitis include:

• Abdominal pain
• Abdominal swelling
• Fever
• Thirst
• Low urine output

Peritonitis may cause your child to go into shock. Signs and symptoms of shock include:

• Cool, clammy skin that may be pale or gray
• A weak and rapid pulse
• Abnormal breathing that may be either slow and shallow or very rapid
• Dilated pupils in the eyes
• Lackluster eyes that seem to stare

A child who is in shock may be conscious or unconscious. If you suspect your child is in shock, seek medical care right away.

When your child arrives at the hospital, the doctors will first stabilize his or her medical condition. This includes giving your child fluids through an intravenous (IV) line and putting a tube through the child's nose and into the stomach (nasogastric tube) to allow the intestines to decompress.

Doctors can often use a barium or air enema to correct the telescoping intestine and successfully treat intussusception. If an enema works, no further treatment is necessary.

Your child will need surgery to treat intussusception if his or her intestine is torn or if an enema is unsuccessful in correcting the problem. The surgeon will free the portion of the intestine that is trapped, clear the obstruction and, if necessary, remove any of the intestinal tissue that has died.

In some cases, intussusception may be temporary and improve on its own without treatment. If no underlying medical condition is found that caused the intussusception, no further treatment is necessary.

Because its cause is unknown in most cases, intussusception usually can't be prevented.