Defining the reliability of bladder scan in patients with obesity with postoperative urinary retention

Postoperative urinary retention warrants catheterization. A bladder scan helps check for postoperative urinary retention before catheterization. There is a paucity of data about its reliability in postoperative obese patients. Our study assesses its reliability in this patient population.

All patients in the postoperative ward of one hospital who underwent surgery during their current admission were included in our prospective cohort study. Patients were catheterized on the basis of the clinical judgment of the treating physician. The nurses collected bladder scan readings before catheterizing patients. Final analysis excluded patients with nongastrointestinal surgeries, record of fewer than 3 bladder scans readings, and missing urinary catheterized volume. The mean bladder scan readings (minimum = 3) were compared with the catheterized volume using intraclass correlation coefficient analysis.

Of 100 patients, 65 met our selection criteria. Bladder scan reliability was good (intraclass correlation coefficient. 0.69; 95% confidence interval, 0.55-0.80) in the overall study cohort. A strong linear relationship was noted between bladder scan and catheterized volumes (r = 0.774, P < .001). Excellent reliability was noted in body mass index <30 subgroup (n = 43, intraclass correlation coefficient, 0.76, 95% confidence interval, 0.61-0.86), whereas the reliability was fair in body mass index ≥30 subgroup (n = 20, intraclass correlation coefficient, 0.55, 95% confidence interval, 0.26-0.81). Patients with body mass index ≥30 had a larger median difference between scan and catheterized volumes compared to patients with body mass index <30 (94.2 mL vs 34.8 mL).

Our study demonstrates the accuracy and reliability of portable ultrasound bladder scans, especially in patients with healthy weight and overweight with postoperative urinary retention. The reliability may be suboptimal in obese patients.