Intussusception usually begins from
**Core Concept**
Intussusception is a condition characterized by the telescoping of one portion of the intestine into another, leading to bowel obstruction and potentially life-threatening complications. This condition often occurs in children but can also affect adults. The pathophysiology involves the abnormal peristalsis and narrowing of the intestinal lumen.
**Why the Correct Answer is Right**
Intussusception typically begins from the ileum, which is the last part of the small intestine. The ileum is most prone to intussusception due to its relatively narrow diameter and the presence of the ileocecal valve, which can act as a lead point for the intussusception. The ileocecal valve is a structure that separates the ileum from the large intestine and can become inflamed or hypertrophied, leading to intussusception.
**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because the jejunum, which is the middle part of the small intestine, is less commonly involved in intussusception.
**Option B:** This is incorrect because the colon is more commonly involved in adult intussusception, not typically the starting point in children.
**Option D:** This is incorrect because the stomach is not a common site for intussusception.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that intussusception is often associated with a palpable abdominal mass and can present with symptoms such as abdominal pain, vomiting, and bloody stools. A classic clinical sign is the "currant jelly" stool, which is a mixture of blood and mucus.
**Correct Answer: C. The ileum.**