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Are true-negative nitrite results affected by a two-hour delay in dipstick/pad analysis of urine in incontinence
1University of North Dakota, School of Medicine and Health Sciences Office of Continuing Medical Education and Outreach, USA. midthuns@gmail.com
Objectives:
To determine if true-negative nitrite results of a urine dipstick pressed into an incontinence pad (dipstick/pad method) are affected by a 2-hour delay in analysis.
Design:
A quantitative study.
Setting And Subjects:
Clean-catch urine specimens from a convenience sample of clinic patients, staff, and long-term care facility residents.
Instrument:
Changes from negative to positive for each group of urine specimens were evaluated using percentages within the groups.
Methods:
Urine specimens were collected and a portion was cultured. Urine specimens negative for a urinary tract infection were included in the study. A portion of the specimen was poured into an incontinence pad. Initial nitrite results were determined using a dipstick pressed into an incontinence pad. Pads with true-negative dipstick/pad nitrite results were tested 2 hours later in the same manner. Urine culture results determined groups: mixed colonies; 50,000 to 75,000 colony-forming units per milliliter of a single type of uropathogen; greater than or equal to 50,000 cfu/mL diphtheroids; no significant growth; and no growth.
Results:
Of the 443 urine cultures negative for a urinary tract infection, 441 initial dipstick/pad nitrite results were negative. Two initial true-negative nitrite dipstick/pad results, or 0.5%, changed from negative to positive over the 2-hour period: 1 in the "mixed colonies" group (0.4%) and 1 in the "no growth" group (0.7%).
Conclusions:
Results of this study indicate that true-negative nitrite results of a dipstick pressed into urine in an incontinence pad do not appear to be affected by a 2-hour delay in analysis.
