In general practice, simple practices should be endorsed to avoid overcomplicating patient management. We have always been told to recommend the use of midstream samples when collecting a specimen of urine for culture, with or without previous cleansing and with or without soap or disinfectants. Notwithstanding, usage of these instructions is variable across practices and across countries. In addition, a midstream urine sample is not always easy to collect, mainly among older patients, let alone when patients are instructed to use external devices as recently analysed by Hayward et al.1
It is no wonder that a high number of patients failed to accomplish the proper use of these devices. The results were expected and the use of two devices did not reduce the number of contaminated samples when compared with the classical procedure of recommending a midstream urine collection. The need to collect a midstream urine clean-catch sample has also been controversial.2. Only Eley et al found a significantly lower number of contaminations among emergency department female patients when they were provided with illustrated instructions about how to collect a proper midstream urine sample compared with those who only received verbal instructions.3 Other studies, however, failed to show a benefit from cleansing prior to sample collection.
We certainly do not know how patients collect the urine samples despite being instructed to perform midstream urine sample collection. No studies have compared first-void or random sampling with midstream urine specimens with urine culture, which is the gold standard. This is the most important question. With the use of paired samples, Hølmkjær et al compared both sampling techniques and found a slightly lower number of contaminations with the use of a midstream urine collection, but urine culture was not used as the gold standard for the two sampling groups, except in those who collected midstream urine specimens.4 To our knowledge, no study has compared the highly recommended midstream urine collection with a first-void urine sample or letting patients with symptoms of urinary tract infection collect the sample as they please. This type of study has yet to be done.
REFERENCES
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