Which condition is characterized by abrupt onset of severe abdominal pain in children?

Intussusception is characterized by an abrupt onset of severe abdominal pain in children because it involves a section of the intestine telescoping into an adjacent segment, leading to obstruction. This condition often presents suddenly, with intense, crampy abdominal pain that can come and go. Additionally, other signs may follow, including vomiting, abdominal distension, or bloody stools, as the condition progresses and complications arise.

In contrast to intussusception, constipation typically presents with discomfort that develops more gradually rather than suddenly. Gastroenteritis usually causes diffuse abdominal pain, diarrhea, and vomiting rather than the localized, severe pain seen in intussusception. Appendicitis can also cause severe abdominal pain, but the pain usually begins around the periumbilical area before shifting to the right lower quadrant, not typically presenting with the abruptness associated with intussusception. Thus, the distinctive nature of the pain and its sudden onset distinctly characterize intussusception in this scenario.