Initial IOC for intussesception is: March 2003
**Core Concept**
Intussusception is a medical emergency characterized by the telescoping of a proximal segment of the intestine into the distal segment, leading to bowel obstruction and potentially life-threatening complications. The initial management of intussusception involves identifying and addressing the underlying cause, which is often a lead point such as a tumor or an intussusceptum that may be a lymphoid hyperplasia.
**Why the Correct Answer is Right**
The initial investigation of choice (IOC) for intussusception is the **abdominal X-ray**, which can show signs of intestinal obstruction, such as a "coiled spring" appearance of the intestine or "target sign" due to the intussusceptum. However, the most useful radiographic sign is the **"meniscus sign,"** which indicates the presence of intussusception. This sign is due to the presence of a crescent-shaped area of soft tissue density between the two layers of the intussusceptum.
**Why Each Wrong Option is Incorrect**
**Option A:** Ultrasound is often used as an alternative imaging modality, especially in pediatric patients, but it is not the initial IOC for intussusception.
**Option B:** CT scan is not typically used as an initial imaging modality due to its high radiation exposure and the fact that it is not as sensitive as other modalities for detecting intussusception.
**Option C:** MRI is not commonly used in the initial evaluation of intussusception due to its high cost, limited availability, and the fact that it is not more sensitive than other imaging modalities for detecting intussusception.
**Clinical Pearl / High-Yield Fact**
The "meniscus sign" is a classic radiographic sign of intussusception, but it is not always present, and a high index of suspicion is necessary for diagnosis.
**Correct Answer: A. Abdominal X-ray.**