Last Updated: 2001-07-06 12:05:32 EDT (Reuters Health)
LONDON (Reuters Health) – Patients with enterocystoplasties tend to have a high proportion of false-positive pregnancy tests, and it appears that mucus is the interfering agent, investigators in London report.
Dr. J. Nethercliffe, of Middlesex Hospital, in London, and associates conducted a pilot study in which they detected false positive pregnancy test results using urine specimens from patients with continent reservoirs, including Kock pouches and Mitrofanoff reservoirs.
The investigators then evaluated 23 patients with urinary reservoirs constructed at least partially of large bowel or ileum. As reported in the British Journal of Urology International for June, eight women and five men exhibited false-positive pregnancy test results.
Urine biochemistry and urine analysis results were similar in the group with false-positive tests and the group with accurate test results. The protein concentrations tended to be higher in the false-positive group. However, a freeze-thaw cycle caused all samples to test negative.
Dr. Nethercliffe's group theorizes that mucus, either by way of cross-reacting epitopes or by abnormal sample migration on the test slide, was responsible for the abnormal test results. The investigators believe that freezing and thawing would cause denaturation of proteins found in mucus.
"If mucus is activating the pregnancy test, it raises the possibility of using the hCG reaction to measure mucus production," the investigators suggest. "To date," they add, "the characterization and measurement of urinary mucus has been difficult."
BJU International 2001;87:780-782.
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