When a child with a UTI does respond to antibiotics within 48 hours, what is the next best step?

When a child with a urinary tract infection (UTI) shows clinical improvement in response to antibiotics within 48 hours, it indicates that the initial treatment is effective. However, it is essential to consider the underlying causes and potential complications, especially in pediatric patients where UTIs can sometimes be associated with anatomical abnormalities or other underlying conditions.

Performing an ultrasound after an initial positive response is a prudent next step. This imaging modality can help assess the urinary tract for any structural abnormalities, such as hydronephrosis, ureteral obstructions, or renal anomalies that may predispose the child to recurrent infections. Addressing any underlying issues early on can help prevent future UTIs and inform the management plan going forward.

The other choices, while potentially useful in different contexts, do not address the need to evaluate for anatomical issues at this stage. Starting intravenous antibiotics may be excessive if the child is responding well. Discharging with a prescription may be premature without confirming that there are no underlying factors to consider. Conducting a urinalysis, while important for initial diagnosis and management, would typically have been done earlier in the evaluation process and is less relevant at this follow-up stage when clinical response has already been established.