## **Core Concept**
Intussusception is a condition where a part of the intestine folds into the section next to it, often causing bowel obstruction and potentially ischemia. In infants, it is a leading cause of intestinal obstruction and bleeding. The etiology can be varied, including infections, anatomical abnormalities, and sometimes a lead point such as a tumor or a Meckel's diverticulum.

## **Why the Correct Answer is Right**
The correct answer, **C.**, implies that the likely cause of intussusception in a 10-month-old infant is a viral infection, most commonly associated with the rotavirus. Rotavirus infections are known to increase the risk of intussusception, particularly in the first two years of life. The mechanism is thought to involve inflammation of the gut-associated lymphoid tissue (GALT), which may act as a lead point for intussusception.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because while anatomical abnormalities can cause intussusception, they are less common in infants and not as directly linked to the age and presentation as viral infections.
- **Option B:** This option is incorrect as there is no common association with bacterial infections as a primary cause of intussusception in infants.
- **Option D:** This option is incorrect because while a Meckel's diverticulum can act as a lead point for intussusception, it is not the most likely cause in a 10-month-old infant without specifying other risk factors.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that the introduction of the rotavirus vaccine has been associated with a decrease in the incidence of intussusception in regions where the vaccine is widely used. Clinicians should be aware of this temporal relationship and consider intussusception in infants presenting with abdominal pain, vomiting, and rectal bleeding.

## **Correct Answer:** . Viral infection