The effect of patient education on mid-stream urine sample collection technique and rates of sterile pyuria and bacterial contamination
Background
Sterile pyuria (SP)identified by urine microscopy or automated flow cytometry is commonly identified in routine ‘mid-urine’(MSU) assessmentat a population level [13.9% in women and 2.6% in men1]. Causes of SP include established antibiotic treatment of a urinary infection, urothelial or renal interstitial inflammation, but most commonis sample contamination by per-urethral cells at the time of collection. The finding of SPfrequently results in the need for further investigation which is a burden for the patient, incurs a substantial healthcare costand may also result in the prescription of antibiotics, where the need is uncertain. Data on its prevalence in populations with chronic kidney disease (CKD) is sparse. Patients with CKDmay have a higher rate of SP as a result of parenchymal inflammation, mycobacterial infection, foreign bodies or stones within the urinary tract but are also at risk of sample contamination as in the general population.2. Little advice is available to patients on how to produce a suitable quality mid-stream urine (MSU) specimen. We conducted an audit to determine the prevalence of SP in our adult CKD population in a tertiary centreandto ascertain whether improved patient education on MSU sample collection might reduce the prevalence of SP.
Subjects and methods
We performed a baseline audit of results of MSUs collected from 96non-transplantpatients with CKD in renal out-patients (Cohort 1). Sterile pyuria was defined as 42 x 105 white cells(flow cytometry) withno significant bacterial growth (<105 bacteria). We then developed a patient information poster, based on the Royal Marsden Manual of Clinical Nursing Procedures, adapted with local microbiology advice.The aim was to improve patients’ technique for collecting MSU samples. Leaflets and verbal instructions were given to patients by the nurses. Posters were displayed in patient toilets. MSU results from two further clinics were re-audited 8 weeks (Cohort 2 and five months (Cohort 3) after the intervention.
Results
SP was common, present in 52 of 288 samples across three cohorts (table 2). Prevalence of SP
was higher in women in each cohort (45 of 134 [34%] women 7 of 154 [4.6%] men: p <0.001, 2 test). Five months after institution of enhanced patient information in our department, there was no change in rates of sterile pyuria across our 3 cohorts, with 16, 17 and 19 SP results respectively (table 1). Results for the third audit did though show a trend for reduction in the rate of heavy mixed growth compared to the previous2 (table 2).
Conclusions.
The baseline prevalence of sterile pyuria inpatients with CKD was higher than that reported in those without kidney disease. Rates are higher in females with CKD than inmale patients. The intervention of improved patient education on MSU sampling was associated with a non-significant reduction in the rate of samples reporting mixed growth but had no impact upon prevalence of sterile pyuria in our study. Further study of the optimal approach to patient education is required. This could include translation of leaflets into appropriate languagesforourpopulation with a rich ethnic mix. Limitations may include shortage of nursing time and patient immobility, which are factors difficult to modify.
References
- Wise GJ; Schlegel PN (2015). Sterile Pyuria. New England Journal of Medicine. March 12, 372 (11); 1048-54.