Estimation Of Bladder Volume Research Articles

Sonografische Harnblasenvolumetrie bei Kindern: vergleichende Beurteilung von konventioneller B-Bild-Sonografie und automatisierter Volumetrie mit einem sonografischen Handgerät ohne Bildgebung

Evaluation of a handheld sonographic tool for the automatic estimation of bladder volume in comparison with conventional sonography in children under clinical conditions. 139 children (age: 30 days - 17 years) were examined with both conventional sonography and the handheld scanning device BVI 6200. For conventional sonography two different formulas were used to calculate the bladder volume. The mean error of the three methods was 22.4 % for the handheld tool, 37.4 % for the most frequently used prolate ellipsoid formula in conventional sonography, and 23 % for an alternative formula recommended in the literature. In 19 cases the first automated sonography scan showed a false-negative result (empty bladder), while the automatically calculated volumes were between 17 and 60 ml in 5 cases of empty bladder. In one of these cases a megaureter and in another an ovarian cyst were detected by conventional ultrasound. Since pathologies are not visualized and can be misinterpreted as a nonempty bladder, the automated method should only be used in follow-up studies. In every case automated volumetry should be performed repeatedly to avoid false-negative results.

Ultrasound Estimation of Female Bladder Volume Based on Magnetic Resonance Modeling

We developed a precise method to noninvasively and conveniently measure female bladder volume greater than 100 ml by ultrasound. Using the proposed method bladder magnetic resonance measurements were made in 7 healthy women to create the volume estimation model. To validate the model for ultrasound application bladder ultrasound images were scanned in 23 healthy women and corresponding volumes were calculated. Calculated and true volumes were compared with the Pearson correlation coefficient and Bland-Altman plots. A total of 51 bladder magnetic resonance images were segmented and reconstructed as 3-dimensional objects. Of the 51 objects 24 had a volume of greater than 100 ml. Based on the 24 objects we regressed the new equation, V = 7.1 x Dl x H - 23, where V represents estimated volume, Dl represents bladder depth and H represents bladder height measured by the proposed method. The estimation was statistically significant (SE 44, r(2) 0.94, p <0.001). A total of 69 ultrasound measurements were made and corresponding volumes were calculated by the equation. The sum of voided and post-void residual volume, when there was any, was considered true volume (range 140 to 995 ml). A significant relationship was found between true and calculated volume (mean difference -3 ml, mean absolute difference 23, r(2) = 0.97, p <0.01). The Bland-Altman 95% limits of agreement were -57 to 51 ml. The proposed method performs well to estimate female bladder volume greater than 100 ml.

Derivations that enable the testing of fetal urine production as a method of fetal surveillance

PurposeTo 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.MethodsThe 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.ResultsThe 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.ConclusionsThe present paper illustrates a careful evaluation of the HFUPR measurement error and the implications of using different ultrasound methods for bladder volume estimations.Electronic supplementary materialThe online version of this article (doi:10.1007/s00404-009-1242-6) contains supplementary material, which is available to authorized users.

Laparoscopic Augmentation Ileocystoplasty: Results and Outcome

BackgroundRoutine use of laparoscopic augmentation ileocystoplasty has not yet been established. ObjectivesTo assess the outcome of laparoscopic augmentation ileocystoplasty. Design, Setting, and ParticipantsTwenty-three patients underwent laparoscopic augmentation ileocystoplasty for hypocompliant bladder. InterventionBladder dissection and reconstruction of the ileovesical anastomosis were performed laparoscopically, whereas the ileal pouch was prepared extracorporeally through a small 3- to 4-cm muscle-splitting incision. MeasurementsPatient data, operative details, and follow-up were recorded. Urodynamic evaluation was performed preoperatively and after 12 mo, taking the bladder capacity and the maximum detrusor pressure as a measure for the outcome of the procedure. Results and LimitationsAll cases were completed laparoscopically, with a mean operative time 202min; mean hospital stay 5 d, and mean urethral catheter duration 11 d. After 12 mo, the estimated bladder volume increased from a mean 111ml to 788ml (p<0.01), whereas the maximum detrusor pressure dropped from a mean 92cm H2O to 15cm H2O (p<0.01). During a mean follow-up of 39 mo, two long-term complications have been reported: bladder stone and spontanous rupture of the augmented bladder due to neglected clean intermittent self-catheterizaton. ConlusionsLaparoscopic augmentation ileocystoplasty is a safe procedure, technically feasible and with favourable urodynamic outcome.

Reliability of an automatic ultrasound system for detecting postpartum urinary retention after vaginal birth

Urinary retention is a common postpartum condition which may lead to short- and long-term complications.Objective. To assess the reliability of a commercially available automatic bladder volume scanner in the puerperium, and to specifically identify women with a post-void residual volume of 400 ml or more. A prospective comparison of ultrasound estimated bladder volume and urine volume measurement after catheterisation in 100 women at risk for postpartum urinary retention (PUR) after vaginal delivery. The mean difference between the ultrasound estimates and the catheter volume measurements was 26 ml, with the corresponding 95% confidence interval (2.6, 49.4 ml). The sensitivity and specificity for the scanner, using the clinically desired value of a 400-ml threshold, are 0.76 and 0.96,respectively. With a perfect classification for sensitivity at a 300-ml threshold, specificity may drop to about 50%. Even using this cut-off point, the number of women catheterised would be reduced by half compared to a procedure of catheterising all women at risk for postpartum urine retention diagnosed by clinical judgment alone. The ultrasound scanner is a reliable screening instrument for detecting PUR after vaginal birth.

The accuracy of ultrasonic estimation of bladder volume: A comparison of portable and stationary equipment

Huang Y-H, Bih L-I, Chen S-L, Tsai S-J, Teng C-H. The accuracy of ultrasonic estimation of bladder volume: a comparison of portable and stationary equipment. Arch Phys Med Rehabil 2004;85:138–41. Objective To compare the accuracy of portable and stationary ultrasonography equipment in estimating residual bladder volume. Design A prospective study. Setting A rehabilitation hospital affiliated with a medical university in Taiwan. Participants Sixty-four patients with voiding dysfunction. Interventions Each patient received both types of ultrasonography, plus catheterization (as the criterion standard for measuring bladder volume). Main outcome measures The mean errors and mean percentage error resulting from use of the 2 types of equipment were recorded. Results Stationary real-time ultrasonography had a lower absolute error (21.9±25.0mL vs 34.4±38.2mL) and percentage error (13.1%±10.5% vs 36%±52.4%) than the portable ultrasonography ( P<.05). Conclusion Stationary ultrasonography provided a more accurate estimate of residual bladder volumes than did the portable device. However, portable ultrasonography is more convenient to use and has an acceptable accuracy for clinical use.

A Probability Model for Ultrasound Estimation of Bladder Volume in the Diagnosis of Female Urinary Retention

Objective: The aim of this study was to evaluate a probability model for ultrasound estimation of bladder volume in the diagnosis of female urinary retention, which is a common condition in the postpartum period. Methods: A total of 53 women with vaginal delivery were recruited on postpartum day 1, and their bladder volumes were first estimated by ultrasound. Immediately after the ultrasound scans the bladders were catheterized for the true bladder volumes. The ultrasound-estimated bladder volumes were then compared with the catheterized bladder volumes. The data were first tested for non-normality, and then logarithmic transformed in order to conform to normality. A probability model was built using the logarithmic-transformed data, based on the following: an arbitrary cut-off value of 150 ml for urinary retention, linear regression analysis, and paired difference analysis. Results: There was a linear relationship between the ultrasound-estimated and catheterized bladder volumes, which can be represented by the equation: log₁₀ (Vc) = 0.2959 + 0.8853 log₁₀ (Vu), where Vc = catheterized bladder volume, and Vu = ultrasound-estimated bladder volume. A normogram was constructed, and the probability of urinary retention presented. Conclusions: The results of this study showed that our method and statistics are logical by which the probability model of urinary retention is precise enough to support clinical decision-making.

The impact of bladder shape on the ultrasonographic measurement of bladder volume in children.

US is used for non-invasive assessment of bladder shape and for calculation of bladder volume. To evaluate the impact of bladder shape on the accuracy of US estimation of bladder volume in children and to calculate formulas for US estimation of volume for different bladder shapes. US was performed in 146 children (94 girls, 52 boys, age range 9 months to 17 years, median 7.9 years) referred for urodynamic investigation. Three bladder diameters were measured, and bladder shapes were categorized as round, ellipsoid, cuboid, triangular and undefined. Urine was collected, and total bladder volume calculated. Correction coefficients (k) were calculated for the whole sample and for each bladder shape using linear regression analysis. Round bladder shape was present in 23%, 25% showed a cuboid shape, 21% an ellipsoid shape, 25% a triangular shape, and 6% had an undefined shape. Correction (regression) coefficient (k) for the whole sample was 0.66 (SE = 0.011); for round bladder 0.561 (SE = 0.013), cuboid bladder 0.923 (SE = 0.012), ellipsoid bladder 0.802 (SE = 0.006), triangular bladder 0.623 (SE = 0.007), and for undefined shape 0.749 (SE = 0.048). Mean percentage errors when using different correction coefficients were significantly lower than errors when using k = 0.5 applied to our data. Bladder shape has considerable impact on the accuracy of US estimation of bladder volume in children. Correction coefficients should be used for volume measurements of different bladder shapes.

Estimation of fetal urinary bladder volume using the sum-of-cylinders method vs. the ellipsoid formula.

A changing hourly fetal urine production rate (HFUPR) has been demonstrated when fetuses are subjected to hypoxia, which is of clinical interest. Conventionally, calculations of the HFUPR have been based on repeated two-dimensional ultrasound bladder images during the filling phase and the formula for ellipsoids. However, the bladder shape changes from the ellipsoidal to super-ellipsoidal during filling and the volume could be underestimated. In this study the sum-of-cylinders method was used, a method which does not depend on the longitudinal bladder shape being an ellipse. The volumes from 102 urinary bladder images from 34 fetuses (three per fetus) were assessed using the sum-of-cylinders method. These results were compared with the corresponding findings when using the ellipsoid formula on the identical material of bladder images in a previous study. When using the sum-of-cylinders method vs. the ellipsoid formula, the mean volume difference was +1.6 mL. Applying the sum-of-cylinders method for bladder volumes of 5-40 mL resulted in standard deviations of 8.8-3.5% vs. 12.9-5.5% when using the ellipsoid formula. No deviation was found when using the sum-of-cylinders method vs. a known volume formula for cylinders, which simulated super-ellipsoids on the computer screen. Volume calculation by the sum-of-cylinders method is independent of the longitudinal bladder shape when it comes to producing accurate estimations. This method demonstrated a systematically larger volume compared with the ellipsoid formula. The sum-of-cylinders method is therefore preferable for volume estimations of the fetal urinary bladder.

Determining the reliability of ultrasound measurements and the validity of the formulae for ultrasound estimation of postvoid residual bladder volume in postpartum women.

To determine the reliability and validity of ultrasonic assessment of the postvoid residual bladder volume (PVRBV) in postpartum women. Ultrasound estimated PVRBVs were performed on 99 consecutive women with postpartum urinary retention, to validate 12 published bladder volume-estimation formulae. This ultrasound-predicted volume was compared with the immediately collected catheterized volume. Comparison of individual formula with the catheterized volumes was performed by using the Intraclass Correlation Coefficient (concordance), and difference plots (bias, linearity of the difference). All volumes were transformed logarithmically to ensure a normal distribution. The postpartum bladder maintained its ellipsoid appearance. One-way analysis of variance showed the variance of the individual formulae ranged from 83.42 to 3463.66 (SD 9.13 to 58.85). The four formulae with the least variance had an intraclass correlation coefficient ranging from 0.93 to 0.96, and a mean difference between volume estimated by the formula and catheterized volume ranging from -0.05 to -0.11 (SD 0.09 to 0.11). The error between the value predicted by the formulae and that of the catheterized volume was linear in only one formula: Volume = (pi x W x Dl x H) / 6. The results of this study have shown that ultrasonic assessment of the PVRBV in the postpartum period is accurate, and it can be used as a guide to whether transurethral catheterization is necessary.

SONOGRAPHIC CHARACTERISTICS OF THE URINARY TRACT IN HEALTHY NEONATES

In infancy it has been reported that intravesical pressure is generally higher in males than in females. We investigated whether there are significant differences in the sonographic characteristics of the urinary tract in male and female neonates. The study comprised 280 consecutive full-term newborns, including 146 males and 134 females. Kidneys were assessed for hydronephrosis and graded according to Society for Fetal Urology guidelines. Kidney measurements included maximum longitudinal length and largest longitudinal area. Bladder measurements included bladder dimensions and wall thickness. Bladder wall thickness was measured only in neonates with an estimated bladder volume of greater than 10 ml. Of the 280 neonates 114 had mild renal pelvic dilatation in at least 1 kidney and the incidence in males was significantly higher than in females (53% versus 27%). Kidney longitudinal length and largest area were significantly greater in males on each side. Mean bladder volume was essentially equal in the 169 male and female neonates with an estimated bladder volume of greater than 10 ml. but mean bladder wall thickness was significantly greater in males than in females (1.63 versus 1.38 mm.). Our study shows that there are marked differences in sonographic findings in male and female neonates in regard to renal pelvic dilatation, renal size and bladder wall thickness. These differences should be considered when sonography is done for screening for urinary tract anomalies in newborns.

Use of a portable bladder scanner to reduce the incidence of bladder catheterisation prior to laparoscopy.

The aim of this study was to evaluate the usefulness of estimating bladder volume with a dedicated portable ultrasound device immediately prior to gynaecological laparoscopy. Catheterisation was performed if the estimated volume was greater than 100 ml. Forty consecutive women were studied prospectively. Twenty-six women did not require catheterisation. The procedure was quick and effective in safely reducing the frequency of pre-operative catheterisation.

Use of a portable bladder scanner to reduce the incidence of bladder catheterisation prior to laparoscopy

The aim of this study was to evaluate the usefulness of estimating bladder volume with a dedicated portable ultrasound device immediately prior to gynaecological laparoscopy. Catheterisation was performed if the estimated volume was greater than 100 ml. Forty consecutive women were studied prospectively. Twenty-six women did not require catheterisation. The procedure was quick and effective in safely reducing the frequency of pre-operative catheterisation.

Comparison of ultrasonographic and radiographic measurements of bladder dimensions and volume determinations

The purpose of this study was to compare the linear dimensions of the bladder measured by ultrasonographic and radiographic methods and the accuracy of these methods for evaluation of bladder volume. Forty dogs were included in this study. Each dog was placed in right lateral recumbency and a plain lateral caudal abdominal radiograph was made. The bladder length and depth were measured in centimetres from the radiograph, taking into account magnification errors. Immediately after radiography was completed, ultrasonographic measurements of bladder length and depth on longitudinal section were measured in centimetres. The bladder was then emptied by catheterisation and the actual urine volume measured. ‘Best subsets’ analysis indicated that radiographic and ultrasonographic bladder lengths were the best predictors of actual bladder volume. Formulae were derived from radiographic and ultrasonographic bladder dimensions for estimating bladder volume. The formula using radiographic measurements was found to be a better predictor of actual bladder volume than the formula derived from ultrasonographic measurements, since it had higher F and lower error mean square values.

Effect of body position on ultrasonographic estimations of bladder volume.

A study was undertaken to determine the effect of body position on ultrasonographic bladder measurements and volume estimations. Of the 42 dogs studied, 15 were fresh canine cadavers without urological disease and the remaining 27 were undergoing investigations for disorders of the lower urinary tract. Bladder volume was estimated using a formula described previously. Irrespective of whether all dogs were considered together or only live animals were included, measurements made in dorsal recumbency tended to underestimate bladder volume while those made in right lateral recumbency resulted in overestimation. This was due to significant differences in all linear measurements, apart from width, between body positions. Measurements in right lateral recumbency were higher than those in dorsal recumbency. In all animals and in living dogs alone, bladder measurements in dorsal recumbency appeared to give a more accurate estimation of actual bladder volume.

Bladder shape impact on the accuracy of ultrasonic estimation of bladder volume

Objective: Variations in bladder shape can lead to errors in ultrasonic estimation of the bladder volume. The purposes of this study were to compare the accuracies of various formulas to estimate bladder volume from sonographic measurements and to assess the impact of bladder shape on the accuracy of bladder volume estimation. Study design: Twenty-four healthy volunteers (13 men, 11 women) and 55 spinal cord injury patients (48 men, 7 women) underwent ultrasonographic measurements of dimensions before and after voiding. Bladder shape was classified as cuboid, ellipsoid, or triangular prism. Ten formulas from the literature were applied to estimate bladder volume, using the volume voided or catheterized as the standard, and then linear regression was used to obtain optimal correction coefficients for the whole data set as well as each of the three bladder shapes. Setting: Rehabilitation hospital affiliated with a medical college. Results: The most accurate of the 10 formulas tested was height (H) × transverse depth (Dt) × weight (W) × 0.7 (mean error 17.4% ± 11.6%). Linear regression analysis yield optimal correction coefficients of .72 for the whole data set and .89, .81, and .66 for cuboidal, ellipsoid, and triangular prism-shaped bladders, respectively. The mean error for the estimation of bladder volume using .72 as the correction coefficient was 16.9% ± 11.9% and decreased to 12.7% ± 10.1% ( p < .0001, paired t test) when the bladder shape was taken into account. Conclusion: Using bladder shape for reference and applying the corresponding correction coefficient to volume calculations will improve the accuracy of the estimation.

Bladder and rectum volume estimations using CT and stereology

Twelve prostate cancer patients underwent a treatment planning CT prior to radiotherapy. Stereologic method based on Cavalieri principle was applied to CT images. Systematic and random sampling of CT slices were performed with alternative ways for assessing the volumes of bladder and rectum. The contribution of point counting to the precision of the obtained volume estimations was analysed. It was found that 100–150 test points counted on only 5–7 systematically sampled slices through bladder or rectum suffice for reliable volume estimations of the above organs. Also, the superiority of systematic vs random sampling was confirmed. The suggested volumetric method gives the possibility of generating unbiased and efficient bladder and rectum volume assessments directly from CT data with great saving in labour.

Hourly fetal urine production rate in the near-term fetus: is it really increased during fetal quiet sleep?

Fetal bladder volume and hourly fetal urine production (HFUPR) is calculated on the assumption that the fetal bladder is ellipsoid in shape. A recent validation study demonstrated a progressive overestimation at increasing bladder volumes. This may be due to changes in shape of the fetal bladder at increasing volumes. Two independent papers have shown increased HFUPR during fetal behavioural state 1F (S1F) when compared with S2F. The aim of the present study was to assess whether this increase of HFUPR during S1F, previously observed by others, could be the result of an error introduced by the method of volume calculation. A retrospective evaluation was performed in a series of 208 HFUPR measurements in 123 normal near term pregnant women attending a low-risk atenatal clinic. Adequate bladder filling in both states was identified in 43 recordings. Maximum fetal bladder volumes were greater (> 10 ml) during S1F in comparison to S2F in 56% of these recordings and HFUPR was significantly greater during S1F only in these cases. Bladder volumes are usually lower during S2F as a result of fetal voiding, which occurred in association with 22 of 36 transitions from S1F to S2F, and only 1 of 13 transitions from S2F to S1F (P < 0.001). When disregarding calculated bladder volumes in excess of 20 ml for the purpose of calculating HFUPR, eleven recordings remained. HFUPR calculated in this way was significantly lower in comparison to measurements where larger bladder volumes were included and no difference was observed between states. This implies that the differences observed are the result of the greater error in calculating bladder volumes and HFUPR during S1F, where volumes are usually greater and that calculation of fetal bladder volume should not be performed on the assumption that the bladder is ellipsoid in shape. Alternative techniques include limiting measurements to a maximum volume of approximately 20 ml, when the bladder is usually ellipsoid in shape or basing volume calculation on the surface area of a series of sagittal views as suggested by Hedriana and Moore [Hedriana HL, Moore TR. Ultrasonographic evaluation of human fetal urinary flow rate: accuracy of bladder volume estimations. Am J Obstet Gynecol 1994;170:1250-1254; Hedriana HL, Moore TR. Accuracy limits of ultrasonographic estimation of fetal urinary flow rate.

Assessment of urinary bladder volume in dogs by use of linear ultrasonographic measurements

SUMMARY Objective To evaluate accuracy of formulas derived from linear ultrasonographic measurements and used in human beings to assess urinary bladder volume as a method of estimating bladder volume in dogs and to test reproducibility of ultrasonographic measurements of linear bladder dimensions. Animals 64 live dogs (for bladder volume determination) and 31 fresh canine cadavers (for ultrasonographic assessment of reproducibility of measurements). Procedure Maximal length, longitudinal and transverse depth (DL and DT), and width were measured from the maximal longitudinal and transverse images. Bladder volume was estimated, using 6 formulas, and calculated volumes were compared statistically with the actual volume obtained by catheterization, using paired nonparametric tests. Reproducibility of bladder dimensions was investigated by measuring length, DL, DT, and width 3 times from each image of section. Measurements of depth (DL and DT) also were compared. Results Calculations of bladder volume from linear dimensions, using a formula described for use in human beings, gave a satisfactory indication of actual bladder volume; the median difference between actual and calculated volumes was only 5 ml. Bladder volume estimations were less accurate when large-volume bladders were measured. Matching between repeated measurements was significant (P &lt; 0.005 for longitudinal bladder length and P &lt; 0.0001 for bladder depth and width). Measurements of DL and DT were significantly (P &lt; 0.01) different, with DL greater than DT. Conclusions Ultrasonographic assessment of bladder volume in dogs by application of the formula is sufficiently accurate for most clinical purposes. Clinical Relevance Ultrasonography would be a useful method of estimating bladder volume in dogs with severe obstruction or dysfunctional voiding of urine. (Am J Vet Res 1998;59:10–15)

Is real-time ultrasonic bladder volume estimation reliable and valid? A systematic overview.

To assess the reliability and validity of real-time ultrasonic estimation of bladder volume we conducted an overview of the published literature identified using MEDLINE search (1966-96) and scanning of the bibliographies of known primary and review articles. Short-listed papers were classified into reliability (observer agreement) and validity (comparison of ultrasound estimation with actual bladder volume) studies. Study selection and data extraction were performed independently in duplicate. There were 81 subjects enrolled in 3 reliability studies and 504 subjects in 16 validity studies. Where reported, the index of concordance for reliability ranged from 0.923 to 1.00, while for validity it ranged from 0.914 to 0.983. However, there were several inadequacies in the design, conduct and analysis of these studies, leaving some doubt about the trustworthiness of the high levels of reliability and validity reported in the literature.