**Core Concept**
Air enema reduction is a minimally invasive, non-operative treatment for intussusceptions, which involves injecting air into the bowel under fluoroscopic guidance to reduce the intussusception.

**Why the Correct Answer is Right**
Air enema reduction works by allowing air to enter the bowel and push the intussusceptum back into its normal position. This is achieved by creating a pressure gradient that helps to dislodge the intussusceptum from the surrounding bowel wall. The air also helps to visualize the bowel under fluoroscopy, allowing the operator to monitor the reduction process in real-time. The success rate of air enema reduction is high, with studies showing a success rate of up to 90% in pediatric patients.

**Why Each Wrong Option is Incorrect**
**Option B:** Saline enema is not effective in reducing intussusceptions because it does not provide the necessary pressure gradient to dislodge the intussusceptum. Additionally, saline can make the bowel wall more slippery, making it harder to achieve a successful reduction.
**Option C:** Barium enema is not the preferred method for reducing intussusceptions because barium can cause peritonitis if it leaks into the peritoneal cavity during the procedure. Furthermore, barium is not as effective as air in creating the necessary pressure gradient to reduce the intussusception.
**Option D:** Hydrostatic reduction is not a recognized treatment for intussusceptions. While hydrostatic pressure can be used to reduce the intussusception, it is not a standard or recommended treatment.

**Clinical Pearl / High-Yield Fact**
It is essential to perform a follow-up imaging study after air enema reduction to ensure that the intussusception has been successfully reduced and that there are no complications, such as bowel ischemia or perforation.

**✓ Correct Answer: A. Air enema**