Intussusception: This is the most common cause of currant jelly stool in a 2-year-old, which is a condition where a part of the intestine telescopes into another part, leading to bowel obstruction and potentially ischemia. The classic triad of intussusception includes abdominal pain, vomiting, and currant jelly stool, although all three are not always present.

Infectious Gastroenteritis: Certain bacterial infections can cause bloody stools that might resemble currant jelly, although the presence of blood is usually accompanied by other symptoms like fever, diarrhea, and abdominal cramps.
Anal Fissure: While more commonly associated with painful defecation and bright red blood, in some cases, the blood can mix with stool to give a currant jelly appearance.

Meckel's Diverticulum: A congenital anomaly of the small intestine that can cause significant gastrointestinal bleeding, potentially leading to a currant jelly appearance of the stool. It's crucial to diagnose and treat promptly to avoid severe complications.
Hirschsprung's Disease: Although typically diagnosed in infancy, some cases might not be identified until later. It can lead to enterocolitis, which might present with bloody stools.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause bloody stools and are important to diagnose early to manage symptoms and prevent complications.

Juvenile Polyps: While usually presenting with painless, bright red rectal bleeding, in rare instances, the blood can mix with stool to give a currant jelly appearance.
Hemolytic Uremic Syndrome (HUS): Typically follows a bacterial infection (like E. coli O157:H7) and can lead to renal failure and microangiopathic hemolytic anemia. Gastrointestinal symptoms, including bloody stools, can be part of the presentation.
Vascular Malformations: Rare congenital conditions that can cause gastrointestinal bleeding, potentially leading to currant jelly stool.