Intussusception

Intussusception is the telescoping of one segment of the intestine into another adjacent distal ("downstream") part of the intestine. (The term "intussusception" is pronounced "in-tuh-suh-sep-shun" with the accent on the "in." It comes from the Latin "intus", within + "suscipere", to receive = to receive within).

Intussusception is the most common cause of intestinal obstruction in children between 3 months and 5 years of age. It is extremely rare in children under 3 months of age or in older children and adults.

During intussusception, a segment of the bowel (intussusceptum) telescopes into a more distal part (intussuscipiens), and drags the associated tissues surrounding the intestine (mesentery, vessels, and nerves) with it. This results in compression of the veins, followed by swelling of the region leading to obstruction and a subsequent decrease in blood flow to the affected part of the intestine. Most cases affect the ileocolic region of the intestine (where the small intestine meets the large intestine).

The compression of blood vessels in the involved intestine reduces the blood supply to the affected intestine. If the blood supply is significantly reduced, the involved intestine may swell, causing an obstruction, or even die (become gangrenous) and bleed. It also may rupture and lead to abdominal infection and shock.

The causes of intussusception are not fully known. Most cases in young children are idiopathic, (meaning the cause is unknown), although some viral and bacterial infections of the intestine may contribute to intussusception in infancy.

Intussusception is very rare in older children and adults. In this population, the causes are believed to be due to polyps or tumors, which are often referred to as the "lead point" of the intussusception.

Most cases of intussusception occur in children between 5 months and 1 year of age. Boys develop the condition two times more often than girls. Intussusception can also occur in adults and older children, although it is uncommon.

Most describe the symptoms of intussusception as a triad of colicky abdominal pain, vomiting, and "currant jelly" stool.

The primary symptom of intussusception is described as intermittent crampy abdominal pain. This is often called "colicky pain." Intussusception in an infant usually starts with the infant suddenly crying very loudly, as if in great pain. The infant intermittently draws the knees up to the chest while crying. This reaction is caused by abdominal pain which recurs frequently and increases in intensity and duration. These intermittent painful episodes are believed to be caused by the telescoping of the bowel and resultant compression of blood vessels and nerves.

In addition to the abdominal pain, most children will also have episodes of vomiting associated with the pain. This vomiting is usually not associated with eating and may be bilious (yellow-green colored)

Some affected individuals who do not seek early medical attention may pass "currant jelly stool". This is a stool that is mixed with blood and mucus and may be a sign that the affected bowel has lost its blood supply and that the bowel may be necrotic (non-viable).

As the condition progresses, the infant may become weaker and develop additional symptoms, including those associated with shock, such as paleness, lethargy, and even fever. However, these are not an integral part of the associated "triad."

Thankfully, most cases are diagnosed early.

Intussusception is an emergency and requires immediate attention.

The history of abdominal pain and vomiting as described above, may suggest the diagnosis of intussusception. Additionally, the examining doctor may feel an abdominal "sausage-shaped" mass (the intussusception itself) or may hear diminished or absent bowel sounds through the stethoscope. Lab tests are usually not helpful, although plain abdominal X-rays can reveal signs of intestinal obstruction, including air-fluid levels, decreased gas, and unexplained masses, usually seen in the right lower quadrant of the abdomen. Ultrasound and CT scans are generally not required to make the diagnosis.

Barium, water-soluble contrast, or air enema is considered both diagnostic and therapeutic in the management of intussusception. This radiologic procedure involves the introduction of the difference into the lower intestine. If intussusception is present, it will be seen during the imaging. Often just the opening of the contrast will reduce the telescoped bowel to its normal position and shape. In these cases, there is a high risk of re-intussusception in the first 24 hours following the enema, though, less commonly, recurrence may be seen several days and even months later.

The treatment of intussusception may or may not require surgery. In some cases, the intestinal obstruction can be reversed with an enema. The enema carries a risk of intestinal rupture and cannot be done if the bowel has already perforated. The procedure also requires the availability of a surgeon, in case the patient's bowel ruptures or the intussusception cannot be reduced.

If an enema cannot reverse the intestinal obstruction, surgery is necessary to change the intussusception and relieve the obstruction. If a portion of the intestine has become gangrenous, it must be removed. After surgery, intravenous feeding and fluids are continued until regular bowel movements resume.

The outlook for intussusception is usually good with early diagnosis and treatment. Early detection and treatment are paramount.

Early diagnosis and treatment of intussusception are essential to prevent injury to the intestine and the associated sequelae, including surgical bowel removal, sepsis, and even death.

Because the cause of intussusception is unknown, there is no known way to prevent the condition.