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Bladder volume calculator5/19/2023 ![]() Postnatally, all infants were investigated by ultrasound at 3-4 months. The A-P and transverse dilatation of the renal pelvis and the bladder dimensions (to calculate fetal bladder volume) were measured at 2-3-min intervals. The women were examined for 2-3 h by ultrasound. To investigate the variation in the dimensions of the fetal renal pelvis in relation to the degree of bladder filling in fetuses with mild pyelectasis.Įighteen third-trimester pregnant women with mild uni- or bilateral fetal pyelectasis, defined as an anteroposterior (A-P) diameter of the renal pelvis between 5 and 10 mm, were recruited for the study. Averaging the equations for sagittal and coronal area volume measurements of the newly proposed technique adds to the error of the method, but the additional error was never greater than ± 13%. In the model, shape changes were unlikely to contribute more than approximately 10% to measurement error and the correlation between both methods of calculating surface area was very high (R = 0.97, n = 64, p 15 min between the first and last volume measurements in a filling period reduced the variation in HFUPR values significantly. Results: The correlation between depth measurements from a transverse view and those from a longitudinal view of the bladder showed that depth measurement was overestimated by approximately 20% in the transverse plane, as a result of tilting of the ultrasound transducer in order to obtain the largest transverse section. The effect of averaging the results obtained from sagittal and coronal area equations on HFUPR was determined mathematically. The latter was examined in a two- dimensional model and from the comparison between true surface areas in longitudinal sections of the fetal bladder, as calculated by a computer program, and the same area was calculated by the mathematical equation for an ellipse. In subsets of the available material, we compared the depth measurements obtained from longitudinal and transverse planes and the effect of shape changes. The effect of the number of bladder volume measurements, and the time interval between the first and last bladder volume measurements, on the variation of HFUPR was determined from data of all cases. At each session, serial measurement pairs (mean number 13, range 2-43) had been obtained from transverse and longitudinal planes of the fetal bladder at 1-5-min intervals during filling periods (mean 28 min, range 0.3-58.8 min). Methods A total of 193 bladder-filling periods were observed in 115 normal, term pregnancies. We examined the effect of averaging the calculated volumes, from coronal and sagittal equations, on subsequent HFUPR measurements. In practice, more or less oblique sections are easier to obtain. A newly proposed method using exact sagittal and coronal area measurements to calculate bladder volume correlated much better with known volumes. Objectives: To determine how commonly used ultrasonographic methods to measure fetal bladder volume and hourly fetal urine production rate (HFUPR) could lead to 40-70% overestimations in a validation study.
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