While there is guidance for urine sampling techniques within young, healthy female populations, there is still ambiguity on how to best manage obese patients. According to the Center for Disease Control (CDC), obesity affect 39.8% of Americans. This percentage increases to 42.8% and 41.0% when focusing on adults aged 40-59 years and adults over 60 years, respectively. This prospective study aims to improve guidelines that are currently ambiguous for over 40% of the patient population. While midstream clean catch has been accepted for young and healthy populations, we plan to elucidate whether midstream clean catch or catheter specimens are superior for diagnosing and treating female patients with a BMI > 30. Clarification on ideal collection technique would result in both proper diagnosis and improved antibiotic stewardship for this population.

Patients who presented to an academic urology department for evaluation with a BMI >/= 30 were recruited. Our primary outcome was to perform a paired analysis comparing each patient’s midstream clean catch urinalysis (UA) and urine culture to their catheter specimen. Midstream clean catch was collected first, and then the patients were catheterized. Both specimens were dipstick tested and sent for culture. The data were analyzed utilizing contingency tables comparing patient’s midstream UA to their catheterization sample within a single subject. Cohen’s Kappa statistic measured agreement between sample collection types. As part of normal standard of care when a subject comes for an initial urological evaluation they are instructed with written and oral instructions regarding how to properly acquire a urine midstream clean catch specimen (MSCC). After the subject provides the urine specimen, a postvoid residual (PVR) test using a catheter inserted into the bladder is done to see how much urine, if any, is left in the bladder. A urinalysis is done in the office on the MSCC specimen and then discarded and the catheterized specimen is sent to the lab for a culture.

Of the 201 patients consented and agreed to be in the study, the average age was 59.6 +/- 13.4 years and BMI was 37.2 +/- 5.9 kg/m2. Dipstick hematuria readings were 67% congruent (k=0.45); nitrites were 97% congruent (k =0.65); leukocytes were 61% congruent (k=0.19); and bacteria were 54% (k=0.35). (Table) Midstream specimen collection values were higher for all but blood on dipstick testing. Bacteria culture specimen collection route were 36.9% congruent (k=0.23). Agreement for positive cultures requiring treatment was 10% (k= 0.23). Interestingly, 74.1% of the midstream urine culture samples reported mixed >3 bacteria vs none in the catheterized specimens (p < 0.001).

Specimen collection results may vary when comparing collection techniques in women with a BMI >/=30. This was demonstrated in the difference in Cohen's Kappa coefficient between the midstream clean catch versus the catheterized specimen.

Among obese females, urine sample testing varied widely between collection method with poor agreement in results. Except for blood, midstream urine collection was more likely to grow pathogenic bacteria, and had a higher likelihood of indicating infection.

Continence 12S (2024) 101670
DOI: 10.1016/j.cont.2024.101670