Final answer:
A CT scan or renal ultrasound may be considered for patients with acute pyelonephritis when there is suspicion of complicated pyelonephritis. These imaging studies can help identify complications and guide management.
Step-by-step explanation:
A CT scan or renal ultrasound may be considered for patients with acute pyelonephritis when there is suspicion of complicated pyelonephritis. Complicated pyelonephritis refers to cases where there is a risk of complications such as abscess formation, renal damage, or obstruction. These imaging studies can help identify such complications and guide appropriate management.