Intussusception in Children on Ultrasound: 'Target' and 'Pseudokidney' Signs
Ultrasound Semiology of Intussusception
In the transverse section, the intussusceptum forms a characteristic concentric pattern — the 'target' sign (bull's eye / target), caused by alternating layers of the bowel wall. In the longitudinal plane, a 'pseudokidney' pattern is observed. According to the source, a pseudokidney pattern (including the hydronephrotic type) can also be caused by lymphomatous involvement of the bowel wall, which should be considered in differential diagnosis (Hagen-Ansert, 2023).
Differential Diagnosis and Mimicry
Intussusception is mentioned as a mimic among fat-containing formations of the peritoneal cavity (ExpertDDx, Zaheer, 2023). Ring-like 'bull's eye' structures in the lower abdomen are also described in inflammatory reactions and bowel loop dilatation, requiring correlation with the clinical picture.
Lead Point
The possibility of sonographic identification of a lead point in intussusception is documented (Stringer MD et al., Arch Dis Child, 1992). Specific ultrasound criteria for types of lead points in fragments are not provided [clarify].
Free Fluid
Free peritoneal fluid can be detected even in uncomplicated intussusception (Swischuk LE, Stansberry SD, Pediatr Radiol, 1991). The clinical significance of isolated free fluid accumulation in children with acute abdominal pain is discussed in separate studies (Matz S et al., 2013).
Viability Assessment
Specific ultrasound criteria and threshold values for assessing the viability of the intussuscepted bowel are absent in the source fragments (e.g., blood flow parameters in color Doppler) [clarify]. The general principle of assessing bowel wall perfusion using Doppler and contrast-enhanced ultrasound is applied in inflammatory bowel diseases (EFSUMB, 2024), but direct extrapolation to intussusception in fragments is not confirmed [clarify].
| Projection | Ultrasound Sign |
|---|---|
| Transverse | 'Target' / bull's eye / target |
| Longitudinal | 'Pseudokidney' (pseudokidney) |
Frequently asked questions
What does intussusception look like in a transverse section?
As a concentric 'target' (bull's eye / target) structure from alternating layers of the bowel wall.
What is the pseudokidney sign?
A longitudinal view of the intussusceptum resembling a pseudokidney; a similar appearance can be caused by lymphomatous involvement of the bowel wall (Hagen-Ansert, 2023).
Can a lead point be identified on ultrasound?
Yes, sonographic identification of a lead point in intussusception is documented (Stringer MD et al., 1992). Detailed criteria for types in fragments are not provided.
Is free fluid present in uncomplicated intussusception?
Yes, free peritoneal fluid can be detected even in uncomplicated intussusception (Swischuk, Stansberry, 1991).
Are there thresholds for assessing bowel viability?
Specific ultrasound criteria and thresholds for the viability of the intussuscepted bowel are not provided in the source fragments [clarify].