Situation: A 65-year-old man weighing 68 kg has an open small-bowel resection under general anesthesia. He returns to the surgical ward with a nasogastric tube to low suction and a wound drain. No urinary catheter was placed, and he is kept nothing by mouth (NPO). Eight hours after he returned to the ward he has not voided. He reports lower abdominal discomfort, and a bladder scan shows 650 mL. Standing at the bedside and running water have not helped. What should the nurse do next?

Failure to void within 6–8 hours with a distended bladder confirmed by scan is urinary retention. Once simple measures fail, the bladder is drained by catheterization as ordered to relieve discomfort and prevent overdistension injury.

Why the bladder is at risk after surgery

This patient has several factors that make postoperative urinary retention likely. General anesthesia temporarily interrupts the micturition reflex, and the small-bowel resection itself, along with postoperative pain and immobility, further suppresses normal voiding. Because he is NPO and has a nasogastric tube on suction, intravenous fluids are the main source of urine output, so the bladder continues to fill even though he has not voided.

Eight hours after surgery, a bladder scan showing 650 mL with lower abdominal discomfort indicates acute urinary retention, not simply low urine output. Normal bladder capacity is roughly 400–600 mL, and volumes above this range place the detrusor muscle under excessive stretch.

Why catheterization is the next step

Simple nursing measures such as standing at the bedside and running water have already failed. When noninvasive voiding prompts are unsuccessful and the bladder is distended, the priority is to drain the bladder with a catheter as ordered to relieve discomfort and prevent overdistension injury. Prolonged overdistension can damage the detrusor muscle and delay return of normal bladder function.

The bladder scan value of 650 mL is above the commonly used threshold for catheterization. One of the referenced sources notes that catheterization is recommended when bladder volume exceeds 600 mL ^[4]. A more recent algorithm for adult inpatients also emphasizes that bladder scanning should guide the decision to catheterize when retention is confirmed ^[1].

Why the other options are not appropriate

Increasing the intravenous rate would worsen bladder filling and increase discomfort without addressing the mechanical problem of retention. Restricting intravenous fluids would not solve the immediate problem of a bladder that is already overdistended, and it could contribute to hypovolemia in a postoperative patient. Applying a warm pack and waiting another 2 hours delays needed intervention and prolongs detrusor stretch.

Intervention	Rationale	Problem
Catheterization	Drains distended bladder, relieves discomfort, prevents overdistension injury	Correct next step
Increase IV rate	Assumes low urine output is the issue	Worsens bladder distension
Restrict IV fluids	Attempts to reduce future urine production	Does not treat existing retention; risks hypovolemia
Warm pack and wait	Noninvasive comfort measure	Already failed simple measures; delays needed drainage

Key point! A bladder scan is the objective tool that confirms retention. When the volume is high and simple voiding measures have failed, catheterization is the standard next action.

Watch out! Do not assume that no urine output means the kidneys are not producing urine. In postoperative retention, urine is being produced but is trapped in the bladder.

Clinical reasoning for the nursing licensure exam

Postoperative urinary retention is common, with reported incidence ranging widely from 5% to 70% depending on surgery type, anesthesia, and patient factors . Older age and certain surgical procedures increase risk ^[4]. The nurse should recognize that a distended bladder confirmed by ultrasound or bladder scan is a clear indication for catheterization when conservative measures fail ^[1][4].

In this patient, the combination of general anesthesia, abdominal surgery, NPO status, and a bladder volume of 650 mL at 8 hours postoperatively supports the diagnosis of acute urinary retention. The correct nursing action is to drain the bladder with a catheter as ordered, because this directly relieves the obstruction, reduces discomfort, and protects the detrusor muscle from further stretch injury.