**Core Concept**
Peterson's hernia is an unusual type of hernia that occurs through a defect in a viscus, such as the intestine, and protrudes into another viscus, like the bladder. This type of hernia is not related to the abdominal wall, which is the primary site of hernia formation.

**Why the Correct Answer is Right**
Peterson's hernia is a rare and distinct category of hernia that occurs through a defect in a viscus, leading to protrusion into another viscus. This type of hernia is not associated with the abdominal wall, which is the typical site of hernia formation. The primary mechanism of Peterson's hernia involves a congenital or acquired defect in the viscus, allowing herniation into an adjacent viscus.

**Why Each Wrong Option is Incorrect**
**Option A:** Amyand's hernia is a type of hernia that involves the appendix, but it still occurs through a defect in the abdominal wall. It does not fit the description of Peterson's hernia.
**Option B:** Richter's hernia is a type of hernia that involves only a portion of the intestinal wall, but it still occurs through a defect in the abdominal wall. It is not related to a viscus-to-viscus defect.
**Option C:** Little's hernia is a type of hernia that occurs through a defect in the abdominal wall, typically in the groin area. It does not involve a viscus-to-viscus defect.

**Clinical Pearl / High-Yield Fact**
Peterson's hernia is an important consideration in patients with unexplained abdominal pain or urinary symptoms, as it can be a rare but serious cause of these symptoms.

**Correct Answer:**
✓ Correct Answer: D. Peterson hernia