The reliability and reproducibility of ultrasonography for measuring the residual urine volume in men with lower urinary tract symptoms

Impact of volume calculation formulae on volume estimation accuracy of different shaped objects: an in vitro ultrasound and CT study

BACKGROUND

In image-assisted volume estimation, the volume of the object is calculated with a formula, using linear measurements of the objects. Since the volume estimation accuracy is thought to be influenced by the shape of the object, the volume estimation error would be related to the calculation formula used.

PURPOSE

To evaluate the volume estimation accuracy of selected volume calculation formulae, for different shaped objects.

MATERIAL AND METHODS

Globular (n = 5), elongated (n = 5), and near-spherical shaped plastic objects (n = 5), filled with water were subjected to ultrasound (US) and computed tomography (CT) in February 2018, to obtain the length, width, depth, and estimated volumes (EV). The volume was calculated manually using prolate, ellipsoid, and Lambert formulae. The actual volume (AV), EV, and calculated volumes were compared.

RESULTS

The AV was in the range of 10-445 mL. The reliability of measurements was high as assessed by the intra-class variability (Cronbach's alpha = 0.992). The EV has shown a high correlation to AV (US: ρ = 0.914, P < 0.001; CT: ρ = 0.943, P < 0.001; ellipsoid: ρ = 0.876, P < 0.001; prolate: ρ = 0.891, P < 0.001; Lambert: ρ = 0.876, P < 0.001). Regardless of the shape, the highest and lowest estimation accuracies were reported for prolate (bias = -0.7) and Lambert formulae (bias = +23.3), respectively. By any method, the globular objects were estimated with the highest accuracy: (US [bias = -0.31]; CT [bias = -0.14]; ellipsoid [bias = -1.5]; prolate [bias = -0.7]; Lambert [bias = 32.9]); and elongated objects were estimated with the lowest accuracy: (US [bias = -17.5]; CT [bias = -32.6]; ellipsoid [bias = -18.4]; prolate [bias = -0.3]; Lambert [bias = 11.4]).

CONCLUSION

The shape of the object and the calculation formula used has an impact on the volume estimation accuracy.

Assessment of 2D ultrasound fluid volume estimation accuracy in different shaped objects: an in vitro study

Background

Volume estimation of organs using two-dimensional (2D) ultrasonography is frequently warranted. Considering the influence of estimated volume on patient management, maintenance of its high accuracy is empirical. However, data are scarce regarding the accuracy of estimated volume of non-globular shaped objects of different volumes.

Purpose

To evaluate the volume estimation accuracy of different shaped and sized objects using high-end 2D ultrasound scanners.

Material and Methods

Globular (n=5); non-globular elongated (n=5), and non-globular near-spherical shaped (n=4) hollow plastic objects were scanned to estimate the volumes; actual volumes were compared with estimated volumes. T-test and one-way ANOVA were used to compare means; P<0.05 was considered significant.

Results

The actual volumes of the objects were in the range of 10–445 mL; estimated volumes ranged from 6.4–425 mL ( P=0.067). The estimated volume was lower than the actual volume; such volume underestimation was marked for non-globular elongated objects. Regardless of the scanner, the highest volume estimation error was for non-globular elongated objects (<40%) followed by non-globular near-spherical shaped objects (<23.88%); the lowest was for globular objects (<3.6%). Irrespective of the shape or the volume of the object, volume estimation difference among the scanners was not significant: globular (F=0.430, P=0.66); non-globular elongated (F=3.69, P=0.064); and non-globular near-spherical (F=4.00, P=0.06). A good inter-rater agreement (R=0.99, P<0.001) and a good correlation between actual versus estimated volumes (R=0.98, P<0.001) were noted.

Conclusion

The 2D ultrasonography can be recommended for volume estimation purposes of different shaped and different sized objects, regardless the type of the high-end scanner used.

Intra- and inter-rater reliability of post-void residual bladder volume with ultrasound

INTRODUCTION AND HYPOTHESIS

The purpose of the present study was to test the intra- and inter-rater reliability of the measurement of post-void residual bladder volume using ultrasound.

METHODS

Two evaluators performed three measurements of the height, width, and length of the empty bladder using ultrasound. The voiding residual volume was calculated using the equation: volume = length × width × height × 0.52. Intraclass correlations (ICC) were calculated considering: ICC ≥ 0.75 excellent, 0.40 ≤ ICC < 0.75 satisfactory, and ICC <0.40 poor, with a significance level of 5% and analysis of confidence intervals (95% CI).

RESULTS

Twenty women participated, with an average age of 27.95 ± 3.15 years. The inter-rater ICCs for height, width, and length were 0.96 (CI 0.89-0.98), 0.88 (CI 0.71-0.95), and 0.84 (CI0.60-0.94) respectively. For the intra-rater ICCs, the values were 0.97 (CI 0.95-0.99), 0.98 (CI 0.96-0.99), and 0.97 (CI 0.94-0.99) for evaluator 1 and 0.99 (CI 0.97-0.99), 0.97 (CI 0.94-0.99), and 0.95 (CI 0.90-0.98) for evaluator 2, for height, width, and length, respectively. The residual inter-test volume was 0.96 (CI 0.90-0.99) and the intra-test volume was 0.99 (CI 0.97-0.99). All analyses presented p < 0.0001.

CONCLUSIONS

The intra- and inter-rater reliability for both the post-void residual volume and measurement of the bladder dimensions showed excellent agreement.

Lower urinary tract symptoms and feeling of incomplete emptying in Saudi Arabian men and its correlation with postvoid residual urine

Purpose:

This study was conducted to assess the clinical value of postvoid residual (PVR) urine measurement and associate it with the feeling of incomplete emptying in men with lower urinary tract symptoms.

Methods:

Two hundred men were surveyed in the King Fahd Hospital of the University. Patients who had previous urological surgery and patients who are currently on urology treatment were excluded. Information from the remaining 181 patients was analyzed. International Prostate Symptom Score (IPSS) sheets were filed, and then, the PVR was measured.

Results:

Data from IPSS sheets were evaluated: 45 patients (24.8%) were characterized as experiencing no symptoms (Score: 0 and 1), 87 (48%) as mild-to-moderate symptoms (Score: 2 and 3), and 49 (27%) as severe symptoms (Score: 4 and 5). The PVR measurement showed no statistical difference in all three categories (being 10, 13, and 12, respectively). Feeling of incomplete emptying despite little PVR was frequently observed.

Conclusion:

The study concluded that the feeling of incomplete emptying was poorly correlated with PVR urine volume measurement. This feeling was significantly associated with worsening of both voiding and storage symptoms.

Can feeling of incomplete bladder emptying reflect significant postvoid residual urine? Is it reliable as a symptom solely?

Purpose

The main objective of this study was to reveal the relationship between lower urinary tract symptoms (LUTS) and post-void residual (PVR) urine volume.

Materials and Methods

Between October 2014 and February 2015, older than 40 years patients were included in this study. Volunteers filled out a questionnaire consisted of demographic characteristics, comorbidities, medications, history of surgery and LUTS. Volunteers were undergone PVR measurement with transabdominal ultrasonography. The relationship between symptoms, demographic characteristics and PVR were analyzed.

Results

A total of 939 patients (756 men and 183 women) were enrolled in this study. There was a positive correlation between the sensation of incomplete bladder emptying and PVR volume in all age groups of women (p=0.0001). However such a relationship was found only over the age of 60 in the subgroup analysis of men (p=0.001). PVR volume increased in men by age (0.65 mL per year of age, p=0.011). In men, voiding symptoms and urgency were associated with a high PVR volume. In women, storage and voiding symptoms (except slow stream and terminal dribble) did not correlate with PVR volume.

Conclusions

Our study showed that all men over the age of 60 years and all women with the complaint of feeling of incomplete emptying should undergone PVR measurement. Women with the complaint of poor stream and men mainly with voiding symptoms are other candidates in whom PVR measurement would be considered as an important tool in the clinical management and follow-up.