Final answer:
The nurse's priority should be to prepare to administer an air enema, as it is a critical intervention that can diagnose and treat intussusception, a suspected condition in infants with red-jelly like stools and abdominal guarding.
Step-by-step explanation:
Prioritizing Nursing Actions for Infants
An infant presenting with red-jelly like stools and symptoms of discomfort during bowel movements, along with findings of abdominal guarding, may be experiencing intussusception a condition where part of the intestine telescopes into itself. This is a medical emergency requiring prompt attention, often managed with an air enema. This procedure can both diagnose and treat the condition, potentially avoiding surgery. The nurse's priority action would be to prepare to administer an air enema, as per physician's orders, to try to correct the intussusception.
While sending a stool sample for a hemoccult test can confirm the presence of blood in the stool and possibly identify causative infectious agents, it is not the immediate priority in a case where intussusception is suspected. Similarly, although assessing the infant's ability to swallow is important, it does not address the acute concern. Giving packed RBCs may be necessary if there's significant blood loss, but it's a subsequent step, dependent on the infant's overall condition and hemodynamic stability.