**Question:** Double bubble sign is seen in –

A. Meckel's diverticulum and duodenal diverticulum
B. Meckel's diverticulum and anal fistula
C. Meckel's diverticulum and ileocecal diverticulum
D. Meckel's diverticulum and appendicitis

**Correct Answer:** C. Meckel's diverticulum and ileocecal diverticulum

**Core Concept:** The double bubble sign is a clinical sign that indicates the presence of two gas-filled structures in the small intestine. In this case, the two structures are Meckel's diverticulum and an ileocecal diverticulum.

**Why the Correct Answer is Right:** The double bubble sign is a non-invasive method to diagnose certain gastrointestinal conditions. In this scenario, it helps identify the coexistence of two anatomical structures: Meckel's diverticulum and ileocecal diverticulum. Meckel's diverticulum is a remnant of the midgut and is commonly caused by an imperforate ileocecal valve, while ileocecal diverticulum is a rare, congenital, and non-functional outpouching of the ileum.

**Why Each Wrong Option is Incorrect:**

A. Meckel's diverticulum and anal fistula: This combination is not associated with the double bubble sign, as anal fistula is a separate condition unrelated to Meckel's diverticulum.

B. Meckel's diverticulum and appendicitis: Appendicitis is an inflammation of the appendix, not a diverticulum, and does not involve the ileocecal region.

C. Meckel's diverticulum and ileocecal diverticulum: This combination is correct as both Meckel's diverticulum and ileocecal diverticulum are located in the ileocecal region, leading to the presence of two gas-filled structures in the small intestine, which is consistent with the double bubble sign.

**Clinical Pearl:** The double bubble sign is an important clinical sign in gastrointestinal (GI) tract pathology and can help guide the physician towards the diagnosis of specific conditions, such as the combination of Meckel's diverticulum and ileocecal diverticulum, which are located in the ileocecal region.

**Why the Correct Answer is Right:** The double bubble sign indicates the presence of two gas-filled structures in the small intestine, which can be associated with various GI tract pathologies. In this case, the correct answer, Meckel's diverticulum and ileocecal diverticulum, are located in the ileocecal region, leading to the presence of two gas-filled structures in the small intestine, which is consistent with the double bubble sign.

**Why Each Wrong Option is Incorrect:**

A. Meckel's diverticulum and anal fistula: This combination is not associated with