A 2-year-old boy is brought to the emergency department by h…
A 2-year-old boy is brought to the emergency department by his father because he has had two episodes of severe abdominal pain during the past 24 hours, which were characterized by crying and drawing his knees up to his chest. The father said the pain seemed to completely resolve after the first episode. The patient has not passed stool during this time. Physical examination shows a cylindrical mass in the abdomen. Cremasteric reflexes are intact bilaterally. Results of ultrasonography are pending. Which of the following is the most likely cause of this patient’s symptoms?