**Question:** Child presents with recurrent abdominal pain and bilious vomiting. Condition was diagnosed by barium follow through. Surgery was done, - mesentric widening, appendicectomy, cutting the Ladd's band. What is the diagnosis?

A. Hirschsprung's disease
B. Meckel's diverticulum
C. Intussusception
D. Inguinal hernia

**Core Concept:**
Recurrent abdominal pain and bilious vomiting in a pediatric patient can be indicative of several gastrointestinal disorders. Barium follow-through, a diagnostic imaging technique, can provide valuable information to help identify the underlying condition. In this scenario, the surgical intervention (mesentric widening, appendicectomy, and cutting Ladd's band) suggests that the diagnosis is related to an anatomical abnormality involving the appendix.

**Why the Correct Answer is Right:**
The correct answer, option C (Intussusception), is the most fitting diagnosis in this case as it involves an anatomical abnormality affecting the appendix. Intussusception is a condition where one part of the intestine telescopes into another, leading to obstruction. In this case, the surgical intervention aligns with the surgical management of intussusception, which includes mesenteric widening, appendicectomy, and cutting Ladd's band.

**Why Each Wrong Option is Incorrect:**

A. Hirschsprung's disease (A) is a congenital disorder affecting the large bowel, characterized by absence of ganglioneuromatosis in the rectosigmoid region. The surgical intervention (mesenteric widening, appendicectomy, and cutting Ladd's band) is not relevant to Hirschsprung's disease.

B. Meckel's diverticulum (B) is a congenital abnormality involving the ileum, typically presenting with gastrointestinal bleeding or abdominal pain. The surgical intervention is not applicable to Meckel's diverticulum.

C. Intussusception (C) is a relevant option as it involves the appendix, which aligns with the surgical intervention.

D. Inguinal hernia (D) is a condition affecting the inguinal region, typically presenting with groin pain or swelling. The surgical intervention is not relevant to an inguinal hernia.

**Clinical Pearl:**

Intussusception is a rare but important diagnosis to consider in pediatric patients presenting with recurrent abdominal pain and bilious vomiting. The surgical intervention mentioned in the question (mesenteric widening, appendicectomy, and cutting Ladd's band) is consistent with the surgical management of intussusception, making option C the correct answer.