title: The effect of physiological urine dilution on pregnancy test results in complicated early pregnancies.
abstract: This study addresses the likelihood of false negative urine pregnancy test results, due to physiological urine dilution as described in some anecdotal reports. In this prospective study 320 pregnancy tests were performed on urine samples of varying concentrations obtained from 40 women, with suspected complications of early pregnancy, who had presented for ultrasound scans. Four different pregnancy tests were used and serum betahCG levels were measured quantitatively. Despite a mean fivefold increase in urine dilution, the pregnancy tests with low betahCG detection limits maintained maximal sensitivity. The detection of betahCG in dilute urine was adversely affected by using pregnancy tests with higher betahCG detection limits and these tests should be used with caution when assessing gynaecological emergencies.
authors.affiliation: Department of Obstetrics and Gynaecology, Whittington Hospital, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Ikomi
authors.forename: M
authors.initials: M
authors.lastname: Matthews
authors.forename: A M
authors.initials: AM
authors.lastname: Kuan
authors.forename: G
authors.initials: G
authors.lastname: Henson
mesh_terms: D015415:Biomarkers / Q000652:urine; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000652:urine; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D009994:Osmolar Concentration; D011247:Pregnancy; D011248:Pregnancy Complications / Q000652:urine*; D011258:Pregnancy Tests / Q000592:standards*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014556:Urine / Q000502:physiology
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human