Postoperative urinary retention or difficulties to empty the bladder in young patients undergoing posterior spinal fusion for adolescent idiopathic scoliosis.

BACKGROUND: Postoperative urinary retention has been reported to affect up to 27% of adults undergoing degenerative lumbar spine surgery and approximately one-third of children undergoing lower-extremity orthopedic surgery. No data exist on the incidence and risk factors of postoperative urinary tract retention/difficulties to empty the bladder in young patients undergoing instrumented posterior spinal fusion. We aimed to characterize incidence, risk factors and treatment of postoperative urinary retention (POUR) and difficulties to empty the bladder in young patients undergoing posterior spinal fusion (PSF) for idiopathic scoliosis.

METHODS: One hundred and eleven consecutive patients (mean age 16years [range, 11-21years], 81 females and 30 males) undergoing PSF for adolescent idiopathic scoliosis were screened after removal of urinary catheter postoperatively for inability to void and residual volume of urinary bladder. The latter was measured using ultrasound on two separate occasions. POUR and the need for intermittent catheterization were defined as an inability to void after catheter removal and documented full bladder with ultrasound (a residual of 300mL or more) or a significant residual volume after voiding (>2mL/kg or >100mL).

RESULTS: Fifty-one (46%) of the patients were either unable to void or had a clinically significant amount of residual volume after voiding. These fifty-one patients required intermittent catheterization for a mean of two days. Thirty patients (27%) had POUR, a residual volume of 300mL or more. Two (1.8%) patients experienced urinary tract infection postoperatively. Patients with urinary retention had a significantly higher mean intraoperative blood loss (mean 626mL vs. 464mL; p=0.020) and longer operation time (mean 3.3h vs. 2.8h; p=0.009) as compared with those not having urinary retention. In multivariate analyses the main risk factor for urinary retention was male gender (odds ratio 3.2 [95% confidence interval 1.1-9.2], p=0.028).

CONCLUSIONS: Postoperative voiding difficulties affect almost half of the patients with age under 21years undergoing PSF for idiopathic scoliosis. The main risk factors were increased intraoperative blood loss, longer length of surgery and male gender. POUR should be actively screened and treated in this patient population.

LEVEL OF EVIDENCE: Prospective Cohort Study II.