Derivations that enable the testing of fetal urine production as a method of fetal surveillance.
OBJECTIVE
To calculate the measurement error of the hourly fetal urine production rate (HFUPR) and evaluate the implication of different methods for measuring the HFUPR, i.e. ellipsoid versus sum-of-cylinders method.


METHODS
The calculation was based on sonographic documentation of the increased bladder volumes during the filling phase, the bladder volume measurement error and the number and time points of bladder image capture.


RESULTS
The probability of a false pathological reading was excluded (0%) with the sum-of-cylinders method for gestational ages of ≥30 weeks. With the ellipsoid method, the risk was higher. The maximum changes which could be exclusively explained by measurement error were four to five times greater with the ellipsoid method compared with the sum-of-cylinders method.


CONCLUSIONS
The present paper illustrates a careful evaluation of the HFUPR measurement error and the implications of using different ultrasound methods for bladder volume estimations.
Department of Obstetrics and Gynaecology, Näl, North Elfsborg County Hospital, 461 85 Trollhättan, Sweden. mats.fagerquist@vgregion.se
Mats A
MA
Fagerquist
Ulf O
UO
Fagerquist
Anders
A
Odén
Sture G
SG
Blomberg
Lars-Ake
LA
Mattsson
D003627:Data Interpretation, Statistical; D005260:Female; D005333:Fetus / Q000502:physiology*; D006801:Humans; D011247:Pregnancy; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal / Q000379:methods; D001743:Urinary Bladder / Q000000981:diagnostic imaging* / Q000196:embryology; D014556:Urine