A 38-year-old man presents to the emergency department with a three-day history of worsening left flank pain, fever, chills, and malaise. He reports that the pain started gradually and has become more intense, radiating to his lower abdomen. He also mentions experiencing nausea and a decrease in appetite over the past few days.

On examination, he has a fever of 102°F (39°C) and is notably tender in the left flank area. Laboratory tests reveal an elevated white blood cell count and signs of dehydration. A urinalysis shows pyuria and bacteriuria. To further evaluate his condition, a CT scan of the abdomen is performed, which reveals a perirenal abscess on the left side, associated with surrounding inflammation.

The patient is diagnosed with a perirenal abscess likely secondary to a complicated urinary tract infection. He is started on intravenous antibiotics and is referred for a urology consultation. A decision is made to perform percutaneous drainage of the abscess under imaging guidance. After the procedure, he is monitored for improvement in symptoms and resolution of the infection. He is educated about the importance of completing the antibiotic course and scheduled for follow-up care.