A 10-month-old infants present with acute intestinal obstruction. Contrast enema X-ray shows the intussusceptions, likely cause is –
Pathogenesis of intussusception 

Between the age of 3 to 9 months, the cause of acute intussusception is idiopathic.
It is postulated that gastrointestinal infection or the introduction of new food proteins result in swollen Peyer's patches in the terminal ileum. The prominent mounds of tissue leads to mucosal prolapse of the ileum into the colon thus causing an intussusception.
In 2-8% of patient, recognizable lead points for the intussusception are found, such as a Meckel's diverticulum, intestinal polyp, neurofibroma, intestinal duplication, hemangioma or malignant condition such as lymphoma.
Peyer's patch hypertrophy
Meclde's diverticulum
Mucosal polyp
Duplication cyst