Intussusception is a medical condition where one segment of the intestine slides into an adjacent part, much like a collapsible telescope. It is most frequently seen in children between three months and three years of age and represents a medical emergency. The telescoping action can lead to a blockage, swelling, and can compromise blood flow to the affected intestinal tissue. Prompt medical attention is necessary, and X-ray imaging is a primary tool for diagnosis and treatment.
Initial Imaging Tests for Diagnosis
When intussusception is suspected, the initial diagnostic process begins with non-invasive imaging. A plain abdominal X-ray is a common first step. While it may not directly visualize the telescoped bowel, it can reveal signs of an intestinal obstruction. Radiologists look for a lack of gas in the right lower quadrant of the abdomen or the presence of a soft tissue mass.
An abdominal ultrasound is frequently the preferred initial imaging test, as it is accurate and does not use ionizing radiation. During an ultrasound, the technician looks for a specific visual marker known as the “target sign” or “bull’s-eye.” This image represents a cross-section of the coiled intestine, providing strong evidence for a diagnosis. The clarity of this sign makes ultrasound a reliable tool for confirming the condition.
The Diagnostic and Therapeutic Enema
The same procedure used to diagnose intussusception can also treat it. This procedure is a therapeutic enema, performed under live X-ray imaging called fluoroscopy. It is a non-surgical treatment that successfully resolves the issue in up to 90% of pediatric cases. A surgeon is available during the procedure due to the small risk of complications.
The process involves placing a small, soft tube into the rectum. Through this tube, a radiologist introduces either air or a liquid contrast agent like barium. The introduction of air or liquid increases the pressure within the large intestine. This pressure is carefully controlled and monitored on the fluoroscopy screen as it pushes against the telescoped segment of the bowel.
The goal is for this gentle pressure to push the trapped portion of the intestine back into its normal position, effectively “un-telescoping” it. The radiologist observes the entire event in real-time, watching the air or contrast move through the colon. This allows them to confirm the location of the blockage and see when it is resolved.
Interpreting the Imaging Results
During a therapeutic enema, the point where the introduced air or contrast material stops flowing marks the location of the intussusception. This blockage often creates a “meniscus sign” or “crescent sign.” This sign appears where the contrast forms a curved shape as it presses against the tip of the telescoped bowel segment.
A successful reduction is visually confirmed when the blockage is cleared. The radiologist will see the air or contrast material flow freely from the large intestine into the small intestine. This indicates that the obstruction has been relieved and the bowel has returned to its proper position.
When Imaging Indicates a Need for Surgery
In some situations, imaging results indicate that surgery is necessary. If the therapeutic enema fails to reduce the intussusception after several tries, the procedure is halted. This requires surgical intervention to manually correct the telescoping bowel.
Another finding from initial imaging that requires surgery is a bowel perforation, which is a hole in the intestinal wall. An abdominal X-ray can reveal free air in the abdomen, a sign of perforation. If a perforation is confirmed, performing an enema is unsafe as it would introduce fluid into the abdominal cavity, so the patient is referred for immediate surgery.