Doublet Sign in Pediatric Intussusception
The "doublet sign" (also called "double target sign") on ultrasound indicates the rare occurrence of double intussusception—two separate telescoping segments of bowel—which requires immediate surgical evaluation and intervention. 1
What the Doublet Sign Represents
The doublet sign appears as two distinct target lesions visible simultaneously on ultrasound imaging, representing two separate intussusception sites occurring concurrently in the same patient. 1 This is distinctly different from the single "target sign" that characterizes typical intussusception, which shows alternating layers of bowel wall creating a bull's-eye appearance on cross-sectional imaging. 2, 3
Clinical Significance and Management Implications
This finding mandates urgent surgical intervention because:
Double intussusception is exceedingly rare and suggests more complex pathology than the typical idiopathic cases seen in infants aged 5-9 months 4, 1
The presence of multiple sites increases the risk of bowel compromise, ischemia, and perforation 2
Pneumatic or hydrostatic reduction (the standard non-operative treatment for single intussusception) is contraindicated when multiple sites are present, as reduction attempts may be incomplete or unsuccessful 1, 2
Lead points are more likely to be present in atypical presentations, though the reported case of double intussusception in a 1-year-old had no identifiable lead point 1
Diagnostic Approach
When evaluating a pediatric patient with suspected intussusception:
Ultrasound is the diagnostic modality of choice with 98.1% sensitivity for detecting the characteristic target lesion 4
Look specifically for the number and location of target signs—a single target sign in the right lower quadrant is typical for ileocolic intussusception, while multiple target signs (doublet sign) indicate double intussusception 1
Document the exact locations of each target sign (e.g., sub-hepatic region and left para-umbilical region as in the reported case) 1
Critical Clinical Pearls
Classic triad of abdominal pain, vomiting, and bloody stools is often absent in intussusception; lethargy and irritability are more common presenting signs 2
Intermittent colicky pain with the infant drawing knees to chest followed by calm periods is the distinctive clinical feature 4
Early diagnosis and prompt surgical treatment are the mainstay of management for double intussusception, as delays increase morbidity and mortality 1, 2
Do not attempt non-operative reduction when the doublet sign is identified—proceed directly to surgical consultation 1