Intussusception is a serious condition in which one segment of the intestine slides, or “telescopes,” into the segment next to it, much like the sections of a collapsible telescope. It occurs most often in infants between four and nine months old, with a peak around six months of age. The telescoping creates a blockage that can cut off blood supply to the affected portion of bowel, making prompt treatment essential.
How the Telescoping Happens
In a healthy digestive tract, wave-like muscle contractions push food steadily forward. In intussusception, a section of bowel gets pulled or pushed into the section immediately ahead of it. The inner, invading portion is dragged along with its blood-supply tissue, which then gets compressed inside the outer portion like a sock folded back into itself.
About 90% of cases in adults involve the small or large bowel, and the small bowel is the most common site overall. In children, the junction where the small intestine meets the large intestine is the typical location. Once the bowel is telescoped, swelling builds quickly. The trapped tissue can lose its blood supply within hours, which is why intussusception is treated as a medical emergency.
Who Gets It
Intussusception is primarily a condition of infancy and early childhood. Hospitalization rates run roughly 182 per 100,000 children under one year of age and drop to about 56 per 100,000 for children between one and two. Incidence is low in newborns under three months and peaks at six to eight months. Boys are affected somewhat more often than girls. Adults can develop intussusception too, but it is rare and typically linked to a structural problem inside the bowel, such as a polyp or tumor.
Common Causes and Triggers
In most pediatric cases, no specific cause is ever found. Swollen lymph tissue inside the intestinal wall, often triggered by a recent viral illness, is thought to act as a “lead point” that gets caught by the normal contractions of the gut and dragged forward into the next segment. Risk factors include recent infections, cystic fibrosis, and intestinal polyps.
When a definite lead point is identified, it is most often a Meckel’s diverticulum (a small pouch present from birth), accounting for roughly 75% of those cases. Polyps make up about 15%, and tumors such as lymphoma account for around 3%. The rotavirus vaccine carries a very small, well-documented increase in risk in the days following vaccination, though the overall benefit of the vaccine far outweighs this risk.
In adults, the picture is different. A structural abnormality, whether benign or cancerous, is found in the majority of adult cases, which is why surgery rather than non-surgical reduction is usually the first-line approach for grown patients.
Recognizing the Symptoms
The hallmark of intussusception in a young child is sudden, severe abdominal pain that comes in waves. Episodes typically strike every 15 to 20 minutes at first. Between episodes, the child may seem relatively calm or drowsy, which can mislead parents into thinking the problem has passed. Over time the painful episodes grow longer and closer together.
Other key signs include:
- Vomiting, which may become bile-stained as the obstruction worsens
- Currant jelly stool, a mix of blood and mucus that takes on a dark, jelly-like appearance
- A sausage-shaped lump that can sometimes be felt in the abdomen
- Lethargy, which can progress rapidly and is sometimes the most prominent symptom
Not every child presents with all of these signs. Currant jelly stool, in particular, tends to appear later in the course and should not be waited for before seeking care. Any infant with episodic, colicky pain and vomiting warrants urgent evaluation.
How It Is Diagnosed
Ultrasound is the go-to imaging tool. It is fast, radiation-free, and highly accurate, with studies showing 92 to 100% sensitivity and specificity for detecting the condition. On the screen, the telescoped bowel appears as a series of concentric rings, often described by radiologists as a “target” or “doughnut” sign in cross-section. Viewed from the side, the overlapping layers resemble a kidney shape. An X-ray may be taken as well, but ultrasound is considered the definitive first step.
Non-Surgical Treatment
For most children, the first treatment attempt is an enema-based reduction. A radiologist gently introduces air or liquid contrast into the rectum under imaging guidance, building enough pressure to push the telescoped segment back into its normal position. The child is awake but usually sedated, and the procedure typically takes only a few minutes.
Success rates are high. In one large study of 351 children, initial attempts succeeded in about 78% of cases at standard pressure. When slightly higher pressure was permitted, the overall success rate climbed to nearly 95% without complications. The procedure is generally safe, though there is a small risk of bowel perforation, which is why it is performed in a setting where surgeons are standing by.
When Surgery Is Needed
Surgery becomes necessary when enema reduction fails, when the child shows signs of peritonitis (infection spreading in the abdominal cavity), or when the bowel has already perforated or suffered visible damage. During surgery, the telescoped segment is manually reduced. If any portion of the bowel has lost blood supply and died, that section is removed and the healthy ends are reconnected.
Children who need surgery generally recover well, though the hospital stay is longer than after a successful enema reduction. Most children are eating normally within a few days of either procedure.
What Happens if Treatment Is Delayed
Timing matters. As the trapped bowel segment swells, its blood supply is progressively squeezed off. This leads to tissue death (necrosis), which can then progress to perforation of the intestinal wall. Once the bowel perforates, bacteria spill into the abdominal cavity, causing peritonitis and potentially sepsis. Bloody diarrhea may develop as dead tissue sloughs away. Each of these complications increases the likelihood of a more extensive surgery and a longer, more difficult recovery.
Recurrence After Successful Treatment
One concern parents often have after a successful enema reduction is whether it will happen again. A large national study from New Zealand found that about 8.5% of children experienced a recurrence within 30 days. Most of those recurrences happened quickly: 3.5% occurred between 4 and 24 hours after the initial reduction. For this reason, children are typically kept for observation in the hospital for several hours following the procedure.
Recurrent episodes are generally treated the same way, with another enema reduction attempt. Repeated recurrences, especially three or more, may prompt doctors to look more carefully for a structural lead point and to consider surgical intervention. Children who have a single episode that is successfully reduced and does not recur carry an excellent long-term prognosis with no lasting effects on bowel function.