1. POSTOPERATIVE URINARY RETENTION IS EXTREMELY COMMON, PARTICULARLY AFTER SURGERY IN
THE LOWER
ABDOMEN, PELVIS, PERINEUM, OR GROIN. THE PATIENT FEELS THE NEED TO VOID BUT CANNOT.
BLADDER
SCANNING AND CATHETERIZATION SHOULD BE PERFORMED 6–8 HOURS POSTOPERATIVELY IF NO
SPONTANEOUS VOIDING HAS OCCURRED. I
2. • Zero urinary output typically is caused by a mechanical problem (not a biologic
one), as even
• patients with renal failure will have some output. Look for a plugged or kinked
catheter, and
• flush the tubing to dislodge any clot that may have formed.
3. • Low urinary output (<0.5 mL/kg/hr) in the presence of normal BP (i.e., not
because of shock)
• represents either fluid deficit or an acute kidney injury. Always check the BP, as
hypotension
• will cause this (renal blood flow follows cardiac output). The treatment is fluids,
not diuretics.
4. • A low-tech diagnostic test is a fluid challenge: a bolus of 500 mL of IV fluids
infused
• over 10–20 minutes. Patients who are dehydrated will respond with a temporary
• increase in urinary output; those in renal failure will not.
• • A more scientific test is to measure urinary sodium: it will be <10 or 20 mEq/L in
• the dehydrated patient with normally functioning kidneys; it will exceed 40 mEq/L
in
• cases of renal failure.
5. • Six hours after undergoing a hemorrhoidectomy under spinal anesthesia, a 62-
year-
• old man complains of suprapubic discomfort and fullness. He feels the need to
void
• but has been unable to do so since the operation. There is a palpable suprapubic
• mass that is dull to percussion. Bladder scanning reveals a significant volume of
urine.
6. • A man has had an abdominoperineal resection for cancer of the rectum, and an
• indwelling Foley catheter was left in place after surgery. The nurses are concerned
• because even though the patient’s vital signs have been stable, urinary output in
• the last 2 hours has been zero.
7. • Several hours after completion of multiple surgery for blunt trauma in an
average-
• sized adult, the patient’s urinary output in 3 consecutive hours is reported as
• 12 mL/h, 17 mL/h, and 9 mL/h. Blood pressure has hovered around 95–130 mm
Hg
• systolic during that time.
