Abstract
The fetal urinary bladder can be observed by ultrasound and the increasing bladder
volume during a filling phase is assumed to reveal the urine production. Volumes,
estimated at different time points within the filling phase, allow the hourly fetal
urine production rate (HFUPR) to be estimated. HFUPR estimations may add to the knowledge
of fetal reactions during obstetrical complications. However, it is essential to know
the degree of measurement uncertainty. Otherwise, small deviations may be overrated
when repeating HFUPR estimations. The purpose of the current paper was to introduce
an interactive program for calculation of HFUPR and the related standard deviation
(SD). Furthermore the aim was to evaluate factors which may influence the SD of HFUPR
estimations. Using the office software Excel, an interactive program was created and
the application was illustrated by the filling phases of 16 fetuses. This material
also enabled different realistic sets of estimation data to be simulated. Thus, SDs
were calculated based on various numbers of documented bladder images and investigation
times. When three instead of two bladder images were used for HFUPR estimation, the
mean of SD was reduced from 22.4 to 8.1 mL/h (p < 0.0001). When the time from the first to the last measurement expanded from 10
to 30 min and four bladder images were used, the mean of SD was reduced from 7.5 to
2.4 mL/h. (p < 0.0001). An interactive program for calculation of HFUPR and the related SD was
provided. Reductions in the SD with increasing number of bladder measurements and
time span between measurements were demonstrated.
Keywords
Fetus - Fetal - Urinary bladder - Ultrasonography - Organ volume - Measurement
