A 3-day-old male newborn presents with the clinical picture shown in the diagram. The infant has not passed meconium since birth and now shows the massively distended abdomen marked **B**. On digital rectal examination, explosive expulsion of stool and gas occurs. The parents are concerned about the underlying cause of this presentation. Which of the following pathophysiologic mechanisms BEST explains the massive abdominal distension marked **B** in this newborn?