NEW YORK (Reuters Health) - A new study has found the method a physician uses for collecting urine from febrile infants may depend more on his or her age than on relevant clinical factors.

An analysis involving more than 3,000 infants treated at practices across the US found that 70% of physicians used catheterization for urine collection, but that the decision to use this method rather than bagging was often not based on an infant's risk of having a urinary tract infection (UTI).

Currently, guidelines recommend catheterization always be used for urine tests because it is considered to be more accurate than other methods, Dr. Robert H. Pantell of the University of California at San Francisco noted in an interview with Reuters Health. However, he and his colleagues point out in the Archives of Pediatrics and Adolescent Medicine's October issue, "the optimal method of urine collection in febrile infants is debatable."

To investigate factors involved in the choice of urine collection method and compare the performance of catheterization to sterile urine bag collection, Dr. Pantell and his team analyzed predictors of urethral catheterization in 3,066 infants with fevers of 38 C or higher treated at 219 practices in 44 states as well as Washington, DC and Puerto Rico.

Catheterization should more readily be used in infants at the greatest risk of having a UTI, Dr. Pantell noted. While clinicians were more likely to perform the more invasive test in female infants, who are indeed at greater risk of UTI than males, they were no more likely to use catheterization in uncircumcised males, who have a 10-fold greater risk than boys who are circumcised.

He and his colleagues also found catheterization was more prevalent in dehydrated infants, which made clinical sense.

However, he noted, the clinician's age also was a major factor; those younger than 40 were more likely to use catheterization than older physicians. Hispanic children and children on Medicaid also were more likely to be catheterized.

There was no significant difference in infection rates between the two methods. While ambiguous cultures were more frequent with bag collection, with 7.4% being ambiguous vs. 2.7% of catheterized samples, it would have been necessary to perform 21 catheterizations to avoid one ambiguous result.

"Probably the most important thing is the sensitivity issue," Dr. Pantell said. "The issue is you did get a few more false positives with the bag."

He added: "The bag really isn't quite as good as the catheter, but people ought to be aware of the differences and take the differences into account when they're making their own decision."

A physician's choice of how to treat an infant with a possible UTI should also come into play when he or she is considering whether to test for the infection and choosing a urine collection method, Dr. Pantell added.

If the provider feels a more intensive, aggressive approach is warranted -- perhaps in a very young, very ill-looking infant -- accuracy is key, while if the clinician feels that a wait-and-see approach with clinical follow-up is more appropriate, more ambiguity is acceptable.

Arch Pediatr Adolesc Med 2005;159:915-922

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