A mother brings her 3-week-old son to the clinic because he is vomiting "all the time." In performing a physical assessment, the nurse notes that the infant has poor skin turgor, has lost 20% of his birth weight, and has a small palpable oval-shaped mass in his abdomen. Which intervention should the nurse implement first?

The client's labs indicate that she has a positive result for group B Streptococcus (GBS) and hepatitis surface antigen, and she is also identified as rubella non-immune.

Ampicillin is the recommended antibiotic for intrapartum prophylaxis against GBS infection to reduce the risk of transmission to the newborn. Administering ampicillin intravenously would help protect the newborn from potential GBS-related complications. Transfusion of packed red blood cells is not indicated based on the hemoglobin and hematocrit values provided. The client's hemoglobin and hematocrit levels, although lower than the reference range, are not critically low and do not necessarily require a blood transfusion.

Injecting hepatitis B immune globulin is not the appropriate intervention in this case. The client is positive for hepatitis surface antigen, indicating active infection, and requires appropriate medical management, which may include antiviral treatment.

Administering the measles, mumps, rubella vaccine is contraindicated during pregnancy. Vaccination for rubella is typically recommended prior to conception or postpartum to prevent congenital rubella syndrome.

A) Incorrect- Dullness bilaterally on percussion is not a normal finding, but it is not an immediate concern after thoracentesis. It may indicate fluid accumulation or consolidation in both lungs, which could be related to other conditions such as pneumonia or heart failure.
B) Incorrect- Serosanguinous drainage from the chest tube is expected after thoracentesis, as long as it is not excessive or continuous. The nurse should monitor the amount and color of the drainage and document it accordingly.
C) Incorrect- Diminished breath sounds in the left lower lobe are also expected after thoracentesis, as the procedure removes fluid and air from the pleural space and reduces lung expansion. The nurse should auscultate the lungs before and after the procedure and compare the findings. The breath sounds should improve gradually as the lung re-expands.
D) Correct- This is a sign of tension pneumothorax, which is a life-threatening complication of thoracentesis. Tension pneumothorax occurs when air accumulates in the pleural space and creates positive pressure that pushes the mediastinum (the heart, great vessels, and trachea) to the opposite side of the chest. This can impair venous return, cardiac output, and respiratory function. The nurse should report this finding to the healthcare provider immediately and prepare to assist with needle decompression or chest tube insertion.