Final answer:
A 37-year-old female with symptoms of a UTI is likely to show White blood cell (WBC) casts on a urinalysis, indicative of an infection in the kidney, such as pyelonephritis.
Step-by-step explanation:
The subject of the question is medicine, specifically relating to the diagnosis of a urinary tract infection (UTI). A 37-year-old female presenting with flank pain, fever, and vomiting, and demonstrating physical signs of costovertebral angle tenderness during examination, is suggestive of a UTI, possibly pyelonephritis which is a type of UTI that has reached the kidney. Considering the clinical context and symptoms, the most relevant finding on urinalysis would be c) White blood cell (WBC) casts.
WBC casts are indicative of infection within the renal tubules and are an important diagnostic clue for pyelonephritis. Other findings in urinalysis, such as pyuria (the presence of pus in the urine), may also be present, reflecting the body's inflammatory response to the infection.
Routine manual urinalysis using a urine dipstick may rapidly screen for infection, detecting substances such as nitrites, leukocyte esterase, protein, or blood that can indicate an active bacterial infection. The leukocyte esterase test in particular detects the presence of neutrophils, signifying an active infection, which aligns with the clinical symptoms described.