Abstract

During a screening survey for urinary infection, 600 infants had one or more urines examined on the sixth or seventh day of life and 592 were subsequently shown to be uninfected. Bacterial and white cell counts on the first urine specimen to be examined from each infant are reported, comprising 363 specimens (188 from boys, 177 from girls) collected into plastic bags and 229 specimens (116 from boys, 113 from girls) collected by a clean catch technique.

Bag specimens contained 5 white cells per mm³ or less in 98% of boys but in only 56% of girls, in whom 11% contained more than 100 white cells per mm³. Clean catch specimens contained up to 5 white cells per mm³ in 97% of boys and 94% of girls, suggesting perineal contamination in girls to be the cause of the higher white cell counts in urine collected into plastic bags.

Total bacterial counts of 10,000 colonies per ml or less were obtained from bag urines in 41% of both boys and girls and from midstream urines of 73% of boys and 77% of girls. Midstream specimens were significantly better than bag specimens for purposes of culture.

Examination of voided urine specimens from newborns allows infection to be excluded in approximately 45% of infants if only one bag specimen is examined and in approximately 75% if a single midstream specimen is obtained. Even bag specimens are therefore not without value.

Suprapubic aspiration should be reserved for infants where difficulty arises due to repeated equivocal results from voided urines, when urgent confirmation is required, or when the presence of perineal lesions makes suitable voided urine collection impracticable.