A nurse is assessing a 9-month-old infant who has shown minimal weight gain. The parent reports the baby eats less than usual and tires easily during play. Both parents are of average height. Which factor is most likely affecting the infant's growth?

A. Administering oxygen via a nonrebreather mask is incorrect as the priority action. Although oxygen can improve fetal oxygenation, it does not directly relieve compression of the umbilical cord, which is the immediate, life-threatening issue in a prolapsed cord. Oxygen may be used after cord compression is relieved, but it is not the first intervention.

B. Placing a rolled towel beneath one of the client’s hips is incorrect because this action alone is insufficient to relieve pressure on the umbilical cord. While positioning such as Trendelenburg or knee-chest may help reduce cord compression, the most immediate and effective intervention is manual elevation of the presenting part.

C. Applying internal upward pressure to the presenting part using two gloved fingers is correct because this action immediately relieves pressure on the prolapsed umbilical cord, restoring fetal blood flow and oxygenation. The nurse must maintain this pressure continuously until the patient is taken for emergency delivery, usually by cesarean section. This is the highest priority life-saving intervention.

D. Increasing the IV infusion rate to provide a fluid bolus is incorrect because fluids do not address the mechanical compression of the umbilical cord. Although IV fluids may be part of overall management, they do not correct the acute cause of fetal hypoxia in cord prolapse.

A. Sweat chloride test is correct because it is the gold standard diagnostic test for cystic fibrosis. In CF, mutations in the CFTR gene lead to abnormal chloride transport in epithelial cells. This results in elevated chloride levels in sweat, typically ≥60 mmol/L in children, which confirms the diagnosis.

B. Genetic testing for CFTR mutations is incorrect as the sole diagnostic tool because not all CF mutations are detectable, and testing may identify carriers or atypical variants. While genetic testing is useful for confirmation or family counseling, it is not the first-line diagnostic test.

C. Chest x-ray is incorrect because, although it may reveal hyperinflation, bronchiectasis, or infiltrates indicative of chronic lung disease in CF, it cannot confirm the diagnosis. Imaging is supportive but not diagnostic.

D. Pulmonary function tests (PFTs) are incorrect because these tests assess lung function and airflow limitation, but they are not diagnostic for CF, especially in young children who may not be able to perform the tests reliably.