A nurse is caring for a 68-year-old male client in the clinic who reports difficulty urinating over the past 2 days. He states he feels the urge to void but is only able to pass small amounts of urine. He also reports lower abdominal discomfort and a sensation of bladder fullness. On assessment, the nurse notes a firm, distended bladder upon palpation. Which of the following diagnostic tests should the nurse anticipate the provider will order to confirm urinary retention?

The clinical presentation describes obstructive symptoms and physical signs of bladder distention. The nurse must apply knowledge of non-invasive diagnostic tools used to quantify retained urine volume specifically to confirm urinary retention and differentiate it from other renal or infectious pathologies. Choice A rationale Cystoscopy involves endoscopic visualization of the bladder and urethra to identify structural abnormalities. While useful for diagnosing the cause of obstruction, it is an invasive procedure and not the initial test to confirm retention. Choice B rationale Bladder ultrasound is a non-invasive bedside tool that measures the amount of urine remaining after voiding. A postvoid residual volume ≥ 100 mL confirms urinary retention by objectively quantifying the bladder volume. Choice C rationale Serum creatinine measures renal function, with normal ranges typically 0.7 to 1.3 mg/dL. While retention can cause post-renal azotemia, this test assesses kidney damage rather than confirming the presence of retained urine. Choice D rationale Urinalysis evaluates for leukocytes, nitrites, and bacteria indicating infection. Although urinary stasis can lead to cystitis, this test identifies inflammation or pathogens but does not provide a measurement of bladder fullness or volume.