A 2 year old boy presents to the clinic with few episodes of sudden onset of colicky abdominal pain for a sho time after which he is completely normal. On examination currant jelly stool was noted in his diapers and a mass was palpated in his abdomen. Which of the following is the most common location of this abnormality?

This child is suffering from intussusception which refers to telescoping of one segment of the bowel into the adjacent segment. The most common form is intussusception of the terminal ileum into the right colon (ileocolic intussusception). It usually occur in children between 6 months and 2 years of age. Children present with episodic sudden onset onset of pain alternating with intervals of apparent well-being. Blood from venous infarction and mucus produce a "currant jelly" stool. On examination, a mass is usually palpable along the distribution of the colon, most commonly in the right upper quadrant of the abdomen. Contrast enema is diagnostic as well as therapeutic in these patients. Ref: Albanese C.T., Sylvester K.G. (2010). Chapter 43. Pediatric Surgery. In G.M. Dohey (Ed), CURRENT Diagnosis & Treatment: Surgery, 13e.