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Urine collection pads (UCPs) are a non-invasive and easy method of sampling urine from young children still in nappies to diagnose or rule out urinary tract infection (UTI).1–3 However, our previous study4 showed a high rate (27%) of sample contamination (>105 mixed growth organisms/ml) by faecal/perineal flora, making interpretation difficult. We hypothesised that reducing the contact time between urine soaked UCP and perineum might reduce this. We therefore devised a new method using the UCP, incorporating the sensor of a personal enuresis alarm buried in its matrix,5 so that the presence of urine in the UCP is signalled, allowing removal of the UCP as soon as urine is passed.
We conducted a randomised trial to compare the contamination rate (>105 mixed growth organisms/ml) of urine obtained from UCPs (checked for urine every 15 minutes) or UCPs incorporating an enuresis sensor (Ferraris fx2000). Febrile children under age 2 (urine sample required to rule out UTI) were randomised to the two collection methods. Urine was aspirated from the UCP using a 20 ml syringe and sent for routine culture. The local research ethics committee approved the study. Consent was obtained from parents.
A total of 91 children were recruited. Pads visibly soiled with faeces were discarded. A total of 71 samples were successfully obtained for culture (UCP 37, UCP/alarm 34). UTI occurred in 7% (5/71). The incidence of heavy mixed growth (>105 organisms/ml) was similar in both groups; UCP 21% (7/34) and UCP/alarm 22% (7/32); odds ratio 1.08 (95% CI 0.3 to 3.5). There were no adverse effects from the alarm and only one false alarm.
Our new UCP/alarm method did not reduce the likelihood of bacterial contamination of the sample. There remains a high rate of contamination by skin and faecal flora inherent in both UCP methods, which is higher than the clean catch method (12%) in our previous study.4 It seems likely that simple contact of the pad with the perineal skin influences the risk of contamination, irrespective of whether the UCP is wet or not. Further work to address this is in progress.
The main benefit of our new UCP/alarm method was its ease and speed of use. The conventional UCP method is already popular with parents.3 Our UCP/alarm method was preferred over the conventional UCP method, because the alarm immediately signals the presence of urine in the UCP and reduces the need to disturb the child for frequent checking of the pad.