Final answer:
The 40-year-old man with a jejunal resection is least likely to require long-term parenteral nutrition, as this part of the small intestine typically allows for compensatory adaptation, unlike the ileum or if there is pre-existing bowel damage.
Step-by-step explanation:
The patient who is least likely to need long-term parenteral nutrition after a small bowel resection is the 40-year-old man with a jejunal resection. The jejunum is one part of the small intestine that typically has a considerable amount of redundancy, and while its resection might impact nutrient absorption, compensatory mechanisms often allow the remaining bowel to adapt over time.
Conversely, the other patients have factors that make parenteral nutrition more likely. A prior radiation enteritis implies pre-existing damage that can complicate intestinal recovery.
An almost total ileal resection means a significant portion of the bowel responsible for absorbing B12 and bile acids is lost, which is critical for digestion and absorption.
Removal of the ileocecal valve, which regulates the flow of material from the small to the large intestine and prevents backflow, also has a higher risk of necessitating long-term support because its absence can disrupt the functional balance of the intestines.