Target (doughnut) sign
PaediatricUltrasound / CT
Concentric alternating rings of bowel wall and mesentery produce a target or doughnut appearance in cross-section.
What it means
Intussusception, where one bowel segment telescopes into the adjacent segment.
Mechanism
The invaginating intussusceptum drags its mesentery into the intussuscipiens, producing concentric layers seen end-on.
Associated conditions
- Ileocolic intussusception
- Meckel diverticulum (lead point)
- Enlarged mesenteric nodes
- Small-bowel intussusception in adults (mass lead point)
Pearls
- On the longitudinal view the same process yields the pseudo-kidney sign.
- In young children it is often idiopathic; in adults, look for a pathological lead point.
References
- Radiopaedia: Target sign (intussusception)
For educational use only. This dictionary is a study aid and reference, not a diagnostic tool, and must not be used to guide clinical decisions or patient care. Imaging appearances vary; always correlate with the full clinical picture and confirm with a qualified radiologist.