Final answer:
The group most likely to be recommended for a renal/bladder ultrasound with a UTI are male children under 2 years old, due to the increased risk of anatomical abnormalities associated with UTIs in this population.
Step-by-step explanation:
Indications for a renal/bladder ultrasound in the context of a urinary tract infection (UTI) generally include those at higher risk for complications or atypical infections. Considering the epidemiology and risk factors associated with UTIs, the correct answer to the question is option a) Male children < 2 years old. Male children under two years of age are less commonly affected by UTIs, but when they do occur, they are more often associated with anatomical abnormalities; hence a renal/bladder ultrasound is usually indicated to rule out such issues. Female children also may require a renal/bladder ultrasound if a UTI is recurrent or atypical. For adult females over 50, the need for an ultrasound would depend on specific clinical circumstances beyond being over 50, such as recurring infections or the presence of other risk factors. Similarly, adult males over 50 might require imaging if there are complicating factors, such as a history of prostatitis or urinary retention issues that can increase the risk of a complicated UTI.