Intussusception is a serious medical condition where a segment of the intestine “telescopes,” or folds, into an adjacent section of the bowel. This telescoping action creates a blockage within the digestive tract, which can compromise blood flow to the affected area. Intussusception is the most common cause of bowel obstruction in young children, particularly those between six months and three years old. A swift and accurate diagnosis is necessary because the condition can rapidly lead to tissue damage and infection.
Understanding Intussusception
The mechanism of intussusception involves the proximal segment of the bowel sliding into the distal segment. This movement often occurs at the junction of the small and large intestines (the ileocolic region), which is the most common site in children. The resulting intestinal obstruction causes swelling and inflammation, putting pressure on the blood vessels supplying the bowel wall.
A lack of blood supply (ischemia) to the trapped segment can lead to tissue death (necrosis). This damage may result in perforation, allowing intestinal contents to leak into the abdominal cavity. Intussusception is considered an abdominal emergency requiring immediate medical attention and rapid imaging.
Initial Screening: What a Plain X-Ray Reveals
A plain abdominal X-ray is often the first imaging procedure performed when intussusception is suspected. While not the definitive diagnostic tool, it serves two important purposes: ruling out other causes and identifying complications like bowel perforation. The presence of free air in the abdominal cavity (pneumoperitoneum) indicates perforation and immediately suggests the need for surgery rather than non-surgical reduction.
Specific findings suggesting intussusception are present in about 60% of cases. The telescoping bowel may appear as an elongated soft tissue mass, sometimes visible in the upper right quadrant of the abdomen. This mass represents the thickened, telescoped bowel loops.
Other suggestive findings relate to bowel obstruction, such as dilated loops of the small bowel filled with air and fluid. The X-ray may also show a noticeable scarcity of gas where the colon is normally located, particularly in the right lower quadrant. This absence occurs because the telescoped bowel blocks the passage of air to the distal colon.
A completely normal plain X-ray does not eliminate the possibility of intussusception, as the sensitivity of this initial screen can be low. Clinicians must rely on the patient’s symptoms and subsequent, more advanced imaging to confirm or exclude the diagnosis. The X-ray is primarily used as a quick check for complications and evidence of severe obstruction.
Definitive Diagnosis and Therapeutic Reduction
Following the initial X-ray screening, the definitive diagnosis of intussusception is most commonly confirmed using an abdominal ultrasound. Ultrasound is the preferred modality due to its high sensitivity (often exceeding 98%) and its ability to visualize soft tissues without using radiation. On ultrasound, the telescoped bowel appears as a characteristic multi-layered structure, often described as a “target sign” or “doughnut sign.”
Once intussusception is confirmed and perforation is ruled out, the next step is often a therapeutic enema procedure. This procedure serves as both a diagnostic confirmation and the primary non-surgical treatment. The enema uses either air or a liquid contrast material, such as water-soluble contrast, which is introduced into the rectum under image guidance, typically fluoroscopy.
The goal of the enema is to use hydrostatic or pneumatic pressure to physically push the telescoped segment of the bowel back into its correct position. When successful, the contrast material or air flows past the point of the intussusception and into the small intestine, confirming that the blockage has been relieved. This non-operative reduction is successful in approximately 82% to 90% of cases in children.
If the enema procedure fails after one or two attempts, or if the child shows signs of peritonitis or bowel necrosis, surgical intervention becomes necessary. During surgery, the surgeon can manually reduce the telescoping bowel. If the tissue is significantly damaged or non-viable due to prolonged lack of blood flow, the necrotic section of the intestine must be removed. Early diagnosis and successful non-surgical reduction are crucial for preventing the need for bowel resection and minimizing risks.