Dipstick Tests: Specimens must be fresh when tested (ie less than 2 hours old). Boric acid (used as a preservative) may give false dipstick results.
Dipstick tests for the rapid diagnosis of UTI have different diagnostic accuracies according to probability of UTI.
Specimen Container: This is a plastic universal with a red screwcap. It contains boric acid crystals as preservative. It is available in two sizes 27 ml and 10 ml. A concentration of 10 g/L of boric acid is obtained when the container is filled up to the mark with 20 ml and 7 ml of urine respectively. Specimens from underfilled containers will yield unreliable culture results as boric acid inhibits some organisms at high concentrations. If only a very small amount of urine is available use a plain universal container.
This type of specimen is collected
after the initial part of the urine stream has been passed having rinsed commensal bacteria from the
urethra. The patient should be instructed to pass a small amount of urine into
the toilet and then pass enough urine to fill the container up to the
mark. The container should not be underfilled as this will result
in a high concentration of boric acid which may kill some organisms and
give a false negative result or a low bacterial count. Cleaning of the perineum is no
longer considered essential if a mid-stream urine is collected
correctly. A first morning specimen is preferred.
A single specimen is adequate in symptomatic adults. In the acutely ill, the elderly and in children, collection of a clean specimen can be difficult and culture results therefore unreliable. In such patients collection of a second sample is recommended.
Urine from catheterised patients should be collected through a sampling port. The sample should not be obtained from the collection bag.
This involves aseptic collection, through the skin, of urine directly from the bladder. It is used for clarification of equivocal results from voided urine.
This is used commonly for infants and young children. The sterile bag is taped over the genitalia and the collected urine is transferred to a sterile leakproof container. Contamination problems are significant.
This is an alternative collection method to bag urine for infants and young children. After washing the nappy area thoroughly a pad is placed inside the nappy. As soon as the pad is wet with urine the tip of a syringe is pushed into the pad and urine is drawn into the syringe. This urine is then transferred into a universal container.
Specimen Transport: Specimens without preservative should be transported immediately to the laboratory or refrigerated. Specimens with boric acid preservative can be stored for longer. Boric acid does however have an inhibitory effect on some organisms so the specimen should be cultured within 24 hours.
receipt in lab)
Cell counts by cytometer: WBC/µl, RBC/µl, urgent - 30 mins
presence of squamous epithelial cells routine - 4 hours
negative culture - 1 day
positive culture - 3 days