Target sign
Cross-section through layered intussusceptum and intussuscipiens.
GI
Intussusception
Intermittent pain and lethargy can precede the classic stool finding by hours.
- Connect ileocolic telescoping to venous congestion, bowel edema, and eventual ischemia.
- Recognize intermittent pain, lethargy, vomiting, and the target sign before late currant-jelly stool appears.
- Choose pneumatic or hydrostatic enema reduction when appropriate and surgery when perforation, peritonitis, instability, or failed reduction is present.
Triage flow
Sort danger before detail
The flow separates immediate stabilization, urgent testing, and definitive source control.
Quick check
A 10-month-old has sudden episodes of screaming and knee flexion separated by quiet lethargy. Ultrasound shows concentric bowel rings.
What is the best next treatment in a stable child without perforation?
Reason it through
- What does the target sign represent?It is a transverse view of bowel telescoped within bowel.
- Why the symptom-free intervals?Peristaltic waves intermittently pull the intussusceptum forward and trigger colicky pain.
- Why can an enema cure it?Air or fluid pressure can push the intussusceptum back through the ileocecal valve.
Idiopathic ileocolic disease versus a structural lead point
Age changes both the likely mechanism and the threshold to search for pathology.
Most cases in infants and toddlers are ileocolic and often follow viral lymphoid hyperplasia of Peyer patches.
A pathologic lead point becomes more likely in older children, recurrent cases, small-bowel intussusception, and adults.
Meckel diverticulum, polyp, lymphoma, duplication cyst, and other masses can be pulled forward by peristalsis.
Compare the common pediatric pattern with lead-point disease.
Often no discrete lesion is found; hypertrophied lymphoid tissue after viral illness may initiate telescoping.
A Meckel diverticulum, polyp, lymphoma, or other structural lead point deserves focused evaluation.
A structural lesion is common, so operative evaluation is usually favored over simple enema reduction.
A short, incidental, asymptomatic segment may self-resolve but needs clinical and imaging correlation.
Catch the presentation before the triad
The classic combination of pain, mass, and bloody stool is memorable but insensitive.
Intermittent severe abdominal pain, vomiting, pallor, and episodic lethargy are common early clues.
A sausage-shaped mass may be palpable, while blood and mucus in stool typically appear later.
Ultrasound is the preferred initial diagnostic test and shows a target or doughnut sign in transverse view.
Choose the finding that should trigger ultrasound now.
Episodic pain with symptom-free lethargyThis waxing and waning pattern is characteristic even before bloody stool appears.
Chronic painless jaundiceThis localizes to hepatobiliary disease rather than intermittent bowel telescoping.
Isolated polyuriaUrinary volume does not suggest an ileocolic obstructive process.
Stable nonbilious spit-up after every feedUncomplicated reflux lacks paroxysmal pain and systemic lethargy.
Let age and physiology move the threshold
Risk is a gradient from typical idiopathic disease to ischemia or a structural lesion.
Infant age, classic episodic symptoms, and ileocolic anatomy favor initial enema reduction when the child is stable.
Older age, recurrent episodes, unusual location, or adult presentation raises the probability of a lead point.
Continuous pain, distention, fever, tachycardia, hematochezia, guarding, and shock raise concern for necrosis or perforation.
Rank the scenarios from routine reduction candidate to operative disease.
See the bowel inside bowel
Imaging signs reflect the orientation of the telescoped segment.
Transverse ultrasound produces concentric hypoechoic and echogenic rings called the target or doughnut sign.
Longitudinal imaging can show a pseudokidney or sandwich appearance with invaginated mesenteric fat and nodes.
Ileocolic intussusception commonly occupies the right abdomen, but the mass can extend across the transverse colon.
Match each view to its anatomic meaning.
Pseudokidney sign
Long-axis view of layered bowel with central mesenteric tissue.
Crescent of mesenteric fat
Dragged-in mesentery within the receiving bowel supports true telescoping.
Free intraperitoneal air
Perforation makes enema reduction unsafe and redirects care to surgery.
Telescoping becomes ischemia
The bowel lumen and mesentery are dragged into the receiving segment together.
The proximal intussusceptum advances into the distal intussuscipiens under peristaltic force.
Mesenteric venous and lymphatic outflow are compressed first, producing edema, obstruction, and mucosal bleeding.
Persistent pressure compromises arterial inflow, causing infarction, perforation, peritonitis, and shock.
Put the mechanism in clinical order.
Choose the first step.
Currant-jelly stool is evidence of injury, not an early screening criterion.
Choose enema reduction or the operating room
Treatment depends on physiology, bowel integrity, and the likelihood of a lead point.
Stabilize with intravenous access, isotonic fluid as needed, analgesia, and surgical consultation before reduction.
Pneumatic or hydrostatic enema under imaging guidance is diagnostic and therapeutic in a stable child without peritonitis or perforation.
Surgery is indicated for shock, peritonitis, perforation, failed enema reduction, nonviable bowel, or a lead point needing resection.
Reveal why each pathway is chosen.
Stable child with likely ileocolic disease and no perforation or peritonitis.
Reduction pressure pushes the intussusceptum proximally.
Persistent telescoping after appropriate enema attempts requires operative reduction.
Repeated force raises perforation risk.
Proceed to surgery after resuscitation and antibiotics.
Enema pressure can worsen contamination.
Resect or otherwise treat the lesion when identified.
Simple reduction alone leaves the cause in place.
First-minute decision
Choose what cannot wait
Choose the clue that changes urgency before refining the diagnosis.
What is the best next treatment in a stable child without perforation?
- Key finding. A 10-month-old has sudden episodes of screaming and knee flexion separated by quiet lethargy. Ultrasound shows concentric bowel rings.
- Answer. Image-guided pneumatic or hydrostatic enema reduction
- Why. A therapeutic enema is first-line for stable ileocolic intussusception without peritonitis or perforation.
- Board rule. Treat the target sign before waiting for the textbook triad.
Stage 1 of 3: Overview
Overview
Intussusception
The bowel lumen and mesentery are dragged into the receiving segment together.
Make the urgent clinical decisions
Five age-specific presentations test early recognition, enema eligibility, lead-point investigation, and operative thresholds.
Cross out unsafe delays and highlight the time-critical clue. Each case asks for the first safe action.
A 9-month-old had coryza last week and now has episodic crying, vomiting, and pallor. Ultrasound confirms ileocolic intussusception.
What most plausibly initiated the telescoping?
Reason it through
- Why does the viral history matter?Lymphoid tissue in the terminal ileum can enlarge after infection.
- What bowel segment usually advances?Terminal ileum commonly telescopes through the ileocecal valve into colon.
- Does this exclude a structural lesion?No, but the age and first typical episode make idiopathic disease more likely.
Why does the viral history matter?What bowel segment usually advances?
- Why does the viral history matter?Lymphoid tissue in the terminal ileum can enlarge after infection.
- What bowel segment usually advances?Terminal ileum commonly telescopes through the ileocecal valve into colon.
- Does this exclude a structural lesion?No, but the age and first typical episode make idiopathic disease more likely.
A 2-year-old has intermittent pain and vomiting for 10 hours. Stool is normal, but ultrasound shows a target sign.
Which treatment is most appropriate?
Reason it through
- Which symptoms are early?Episodic pain, vomiting, pallor, and lethargy can precede stool changes.
- What creates currant-jelly stool?Ischemic mucosa sheds and mixes with blood and mucus.
- What is the treatment window trying to prevent?Progression to necrosis, perforation, and shock.
Which symptoms are early?What creates currant-jelly stool?
- Which symptoms are early?Episodic pain, vomiting, pallor, and lethargy can precede stool changes.
- What creates currant-jelly stool?Ischemic mucosa sheds and mixes with blood and mucus.
- What is the treatment window trying to prevent?Progression to necrosis, perforation, and shock.
A stable 14-month-old has ultrasound-confirmed ileocolic intussusception. Radiographs show no free air, and the abdomen has no guarding.
Which therapy is preferred?
Reason it through
- What makes enema safe enough here?There is no shock, peritonitis, or evidence of perforation.
- How does success appear?Contrast or air passes into terminal ileum with disappearance of the mass.
- Who remains involved?Surgical support is needed because reduction can fail or rarely perforate bowel.
What makes enema safe enough here?How does success appear?
- What makes enema safe enough here?There is no shock, peritonitis, or evidence of perforation.
- How does success appear?Contrast or air passes into terminal ileum with disappearance of the mass.
- Who remains involved?Surgical support is needed because reduction can fail or rarely perforate bowel.
A 7-year-old has a third intussusception after two successful enema reductions. Imaging shows a focal intraluminal lesion near the terminal ileum.
What is the best next management?
Reason it through
- What makes this unlike typical infant disease?The child is older and has repeated recurrence.
- What does the focal lesion imply?A persistent structure may be dragged forward by peristalsis.
- What must surgery accomplish?Reduce viable bowel and remove or biopsy the responsible lesion.
What makes this unlike typical infant disease?What does the focal lesion imply?
- What makes this unlike typical infant disease?The child is older and has repeated recurrence.
- What does the focal lesion imply?A persistent structure may be dragged forward by peristalsis.
- What must surgery accomplish?Reduce viable bowel and remove or biopsy the responsible lesion.
A 68-year-old has obstruction, and CT shows enteroenteric intussusception with a mass at the leading edge.
What is the most appropriate next step?
Reason it through
- Why does age change the mechanism?A tumor or other structural lesion is much more common in adult intussusception.
- What does CT add?It defines obstruction, ischemia, location, and the suspected lead mass.
- Why is simple reduction insufficient?The pathologic lead point remains and may be malignant.
Why does age change the mechanism?What does CT add?
- Why does age change the mechanism?A tumor or other structural lesion is much more common in adult intussusception.
- What does CT add?It defines obstruction, ischemia, location, and the suspected lead mass.
- Why is simple reduction insufficient?The pathologic lead point remains and may be malignant.
Rapid review
Three questions to check
What is the best next treatment in a stable child without perforation?
Image-guided pneumatic or hydrostatic enema reduction. A therapeutic enema is first-line for stable ileocolic intussusception without peritonitis or perforation.
Why does the viral history matter?
Lymphoid tissue in the terminal ileum can enlarge after infection.
What bowel segment usually advances?
Terminal ileum commonly telescopes through the ileocecal valve into colon.
Medically reviewed
Fatima Ali, DO
PGY-1 Resident Physician in Psychiatry
University Hospitals, Columbia
DO from Kansas City University
Resident physician and founding medical reviewer at Bone Wizardry, focused on clinical accuracy, clear diagnostic reasoning, and practical board-oriented teaching across the curriculum.
Languages: English, Urdu
Primary reviewerFull physician profile
Medically reviewed
Sources
- Child Intussusception2023
- Intussusception in Adults2026
- ACR Appropriateness Criteria: Abdominal Pain-Child2026
Bone Wizardry is a study resource for medical students. It is not medical advice.