Postpartum Urinary Retention
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Direct answer
Postpartum urinary retention is failure of the bladder to empty adequately after delivery, most often after a prolonged labour, instrumental birth or regional anaesthesia. It is overt when the woman cannot pass urine at all, and covert when she voids but leaves a large residual volume. Management is catheterisation guided by bladder scanning, followed by a trial without catheter before discharge.
What you must remember
- Overt retention: complete inability to void, usually noticed when the woman has not passed urine within about six hours of delivery.
- Covert retention: voiding that appears normal or frequent but leaves a significant post-void residual, so it is easily missed.
- Risk factors: epidural or spinal anaesthesia, instrumental delivery, prolonged second stage, perineal oedema or trauma, and bladder overdistension during labour.
- Bladder scanning: a residual volume above about 150 mL is commonly used as the threshold for catheterisation, though local protocols vary.
- Catheter choice: intermittent catheterisation is preferred, since it carries a lower urinary infection risk than an indwelling catheter.
- Trial without catheter: the catheter is removed and voiding and residual volumes are checked before the woman is discharged.
- Red flag: retention with leg weakness, saddle anaesthesia or bowel symptoms after neuraxial anaesthesia suggests a neurological complication such as spinal haematoma, and needs urgent review.
Managing retention in the puerperium
A woman who has not passed urine after a difficult birth needs her bladder assessed rather than reassured. The steps below set out a usual sequence.
- Suspect retention early: consider it when there is no voiding within about six hours, a palpable bladder or discomfort above the pubic symphysis.
- Measure the residual: scan the bladder to estimate its volume, and repeat the measurement after voiding where covert retention is suspected.
- Catheterise intermittently: empty the bladder with an intermittent catheter, noting the volume drained, because overdistension can impair detrusor function.
- Use an indwelling catheter only if needed: reserve it for situations where repeated catheterisation is not feasible, and remove it as early as possible.
- Run a trial without catheter: remove the catheter and check voiding and residual volumes over the following hours.
- Escalate when the trial fails: repeat catheterisation, look for pelvic and neurological causes, and refer for specialist review if retention persists.
Where the exam tries to catch you
Questions here reward recognising retention that hides behind normal-looking voiding.
- Trap: Ignoring a woman who passes small volumes frequently. Correct: Overflow from covert retention produces frequent small voids, so a bladder scan is needed before dismissing the complaint.
- Trap: Keeping an indwelling catheter for days for convenience. Correct: Prolonged indwelling catheterisation raises infection risk, so intermittent catheterisation is preferred.
- Trap: Discharging the woman after one successful void. Correct: A single void does not confirm recovery, and residual volumes should be checked before she goes home.
- Trap: Attributing leg weakness after an epidural to the usual effects of the anaesthetic. Correct: Motor weakness with retention after neuraxial anaesthesia may signal spinal haematoma, which is an emergency.
Frequently asked questions
What bladder volume threshold prompts catheterisation after delivery?
A post-void residual above about 150 mL on bladder scanning is commonly used as the threshold for catheterisation after delivery. Local protocols vary, so the threshold should follow the institution's policy.
How do overt and covert postpartum urinary retention differ?
Overt urinary retention means the woman cannot pass urine at all, while covert retention means she voids but retains a significant residual volume. Covert retention is easily missed because the woman appears to be passing urine normally.
Why is intermittent catheterisation preferred over an indwelling catheter?
Intermittent catheterisation carries a lower risk of urinary tract infection than an indwelling catheter. It also allows the bladder to be emptied while the woman's voiding function is reassessed.
Which anaesthetic techniques raise the risk of postpartum urinary retention?
Epidural and spinal anaesthesia both raise the risk of postpartum urinary retention by blunting bladder sensation. The risk is higher with prolonged epidural use, and it adds to the risk from instrumental delivery.