# Post-void residual measurement: A comprehensive review of the clinical relevance and precision of bladder scanner devices

Giulia Manfredini, Julien Anract, Nicolas Barry Delongchamps

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Giulia Manfredini, Julien Anract, Nicolas Barry Delongchamps. Post-void residual measurement: A comprehensive review of the clinical relevance and precision of bladder scanner devices. The French Journal of Urology, 2025, 35 (5), pp.102870. 10.1016/j.fjurol.2025.102870. hal-05105867

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## Literature Review

# Post-void residual measurement: A comprehensive review of the clinical relevance and precision of bladder scanner devices

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# Pertinence clinique et précision des différents dispositifs de bladder scanners dans la mesure du résidu post-mictionnel : une revue de la littérature

Giulia Manfredini<sup>a</sup>, Julien Anract<sup>a,b,*</sup>, Nicolas Barry Delongchamps<sup>a,b</sup>

## ARTICLE INFO

**Keywords:**
* Bladder
* Residual
* Post-void
* Bladder scanner

## ABSTRACT

**Objective:** To evaluate the accuracy of bladder scanners in measuring bladder volume and to compare their precision.

**Method:** MEDLINE and Cochrane databases were searched from January 1, 1990 to December 30th, 2023. We selected studies assessing results of bladder volume measurement using bladder scanners, standard ultrasonography or bladder catheterization.

**Results:** In total, 177 studies were screened, of which 22 were included in the final analysis. According to the literature, there is no clinically significant difference in the measurement of bladder volume using urethro-vesical catheterization, bladder scanner, or conventional ultrasound. Studies comparing different types of bladder scanners did not show any difference in accuracy.

**Conclusions:** Bladder scanners are precise tools to evaluate bladder volume in urological patients, applicable in daily practice. Knowledge of the patient's medical history is crucial to better interpret the measurement.

© 2025 The Authors. Published by Elsevier Masson SAS. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

## RÉSUMÉ

**Mots clés:**
* Vessie
* Résidu
* Post-mictionnel
* Bladder scanner

**Objectif:** Évaluer la précision des scanners vésicaux dans la mesure du volume vésical et comparer leur précision.

**Méthode:** Les bases de données MEDLINE et Cochrane ont été consultées du 1er janvier 1990 au 30 décembre 2023. Nous avons inclus toutes les études sélectionnées évaluant les résultats de l'analyse des mesures du volume vésical à l'aide de scanners vésicaux, d'échographes standards ou de cathétérisme vésical.

**Résultats:** Au total, 177 études ont été examinées, et 22 d'entre elles ont été incluses dans l'analyse finale. Selon la littérature, il n'existe pas de différence cliniquement significative dans la mesure du volume vésical par cathétérisme urétrovésical, scanner vésical ou échographie conventionnelle. Les études comparant différents types de scanners vésicaux n'ont montré aucune différence de précision.

**Conclusions:** Les scanners vésicaux sont des outils précis pour évaluer le volume de la vessie chez les patients urologiques dans les soins courants. La connaissance des antécédents médicaux du patient est cruciale pour mieux interpréter la mesure.

© 2025 Les Auteurs. Published by Elsevier Masson SAS. Cet article est publié en Open Access sous licence CC BY (http://creativecommons.org/licenses/by/4.0/).

<footnote><sup>a</sup> Urology Department, Cochin Hospital, Université Paris Cité, Paris, France</footnote>

<footnote><sup>b</sup> Inserm U1151, Institut Necker-Enfants-maladies (INEM), Paris, France</footnote>

<footnote>* Corresponding author at: Service d'urologie, hôpital Cochin, 123, boulevard de Port-Royal, 75014 Paris, France.
E-mail address: julien.anract@aphp.fr (J. Anract).</footnote>
# 1. Introduction

The reference method to evaluate post-void residual (PVR) is drainage by bladder catheterization followed by measuring the volume of urine drained into a urinal.

This method is invasive, and therefore at risk of iatrogenic complications as sepsis, urethral trauma, bleeding and pain [1].

An estimation of bladder volume can be carried out by ultrasound using different methods.

The most common is to measure the bladder dimensions on the 3 axes, followed by using the “prolate ellipsoid formula”: the 3 axes are multiplied between them and by a corrective factor, which depends on the shape of the bladder [2].

If we consider the bladder to be ellipsoidal in shape, the corrective factor, which corresponds to 0.52, derives from the formula: $\frac{4}{3}\pi \times (\text{width}/2) \times (\text{depth}/2) \times (\text{height}/2)$, which can be simplified by $\text{width} \times \text{depth} \times \text{height} \times 0.52$, as shown by Roehrborn and Peters [3].

Another calculation method, described by Rageth and Langer, is the “double area formula”: $\text{Volume} = \exp[C1 + C2 \times \log(A1) + C3 \times \log(A2)]$, where A1 and A2 are the areas of the bladder taken on a transverse and longitudinal section and C1 = 0.8304, C2 = 0.5625, C3 = 0.7211 are coefficients obtained by a multiple linear regression analysis [4]. Hvarness et al. recommend using the three-axis formula because of its simple and fast method, providing no significant differences in results for bladder volumes between 45 mL and 508 mL [5].

The development of portable ultrasound machines, called bladder scanners (BS), has improved the patient management. Their use is simpler and faster than the traditional ultrasound machines because they allow an automated measurement of bladder volume. The BS transducer automatically switches and acquires images on different bladder sections, allowing a bladder volume to be constructed and then measured according to an algorithm, which varies depending on the BS model [6].

Since the first BS was put on the market, several devices have been developed and improved. To date, several models are available in healthcare settings [7].

The objective of this review was to compare the precision of the most common BS and to discuss the relevance of their indications.

# 2. Methods

A literature review was conducted in December 2023 on Pubmed database using 3 MeSH terms (“bladderscan”, “bladder scanner” and “portable bladder ultrasound”), thus identifying a total of 762 articles. Articles written in another language than English of French, veterinary and duplicate records were excluded. This identification phase selected 490 articles for the screening phase. Two reviewers (GM and NB) conducted the screening phase, via abstract analysis, looking for the following keywords: “accuracy”, “comparison”, “precision”, “variable error”, “measurement”, “post void residual”, “catheterization”, “bladder volume”, “urinary retention”. In total, 177 abstracts were selected by this screening phase. Two reviewers (GM and JA) conducted the final selection via full text reading, looking for the following outcomes: – The precision of BS for measuring bladder volume compared to bladder catheterization – The differences between BS and conventional ultrasound machines and the comparison between the different models of BS on the market. Finally, 23 articles met the inclusion criteria and were included in the review (Fig. 1). Additional research for methods to calculate bladder volume was conducted.

# 3. Results

We included 21 studies comparing the accuracy of BS versus catheterization and 5 studies comparing BS with each other.

Table 1 summarizes the characteristics of the BS most frequently found in the PRISMA analysis of the literature. The accuracy reported on the BS technical specifications is evaluated using bladder phantoms. However, precision is not always clinically validated.

## 3.1. Studies comparing BS with bladder catheterization

Table 2 summarizes studies comparing the volume measured by BS and the volume obtained by catheterization. Most of the population were women, probably due to less traumatic catheterization.

The mean difference in measured volumes was between 2.4 mL and 312 mL [8,9].

The correlation coefficients between urinary volume measured by catheterization and by BS ranged from 0.59 to 0.98 [9–21].

All studies, except for three, validated the use of BS [9,21,22].

Pallis et al. conducted a prospective study in 27 women on postoperative day 1 after vaginal delivery. They reported an overestimation of the volume measured by the BS of an average of 130 mL (with limits ranging from 156 mL in underestimation to 422 mL overestimation) [21].

Salimans et al. observed a mean overestimation of 300 mL in 25 postpartum women [9].

The third study was carried out by Brouwer et al. [22]. They compared the BS BVI 9400, the BS Prime and urinary catheterization in 318 patients, men and women, both intraoperatively for surgical interventions (arterial bypass, orthopedic surgery or colon surgery) and postoperatively (patients under surveillance who were unable to urinate spontaneously).

The authors reported that both devices were able to give a good estimated volume (mean difference being 22 mL for the BVI 9400 and -21 mL for the Prime). Nevertheless, estimated volume was outside the ±5% boundaries predefined by the study. The BVI 9400® overestimated the volume by +17.5% average, while Prime underestimated by -4.1% (without the pre-scan function) and -6.3% (with the pre-scan function).

Some studies have reported several factors associated with the accuracy of the BS [8,12,23–28].

In the study of Theisen et al, evaluating the BS Biocon 700® in 70 patients with pelvic prolapse, the accuracy was lower in the case of grade III and IV prolapse [24]. No difference was observed depending on whether the prolapse was anterior or posterior. The authors suggested that the lack of precision was linked to changes in shape induced by prolapse on the bladder volume.

Jensen et al. reported a decreasing in measurement accuracy in cases of bladder volume < 150 mL in the immediate postpartum period [25].

Two studies reported the negative impact of body mass index on the precision of the measurement [8,22]. However, results are discordant with Majima et al. showing a significative difference in case of BMI > 25, whereas Brouwer et al. showed no significant difference.

Other factors impacting the accuracy were the presence of pelvic cysts [26,28] and the presence of ascites [27].

## 3.2. Comparative studies between BS

Table 3 summarizes five studies selected for the analysis [29–31].

The BS BVI 3000® was the most represented.

Main outcomes were either the volume urinated or the volume obtained by catheterization.

In the study by Ghani et al., a conventional ultrasound scanner (3D-US) was also used as a comparison [32].

As reported in Table 3, none of these studies observed a significant difference between the different measured volumes.

# 4. Discussion

The information provided by non-invasive PVR measurement is crucial in various areas of patient care:

* in postoperative situations, including general or regional anesthesia, resumption of spontaneous voiding should be monitored, particularly in elderly patients or in men with known symptomatic benign prostatic hyperplasia [33];

* in the postpartum period, the risk of urinary retention is particularly high. Its incidence varies in the literature from 0.18 to 14.6% [34];
<figure><img src="image_3.png" /></figure>

* Number of articles excluded through title/abstract screening
** Number of articles for which the full text is not found

<caption>Fig. 1. Analysis of the literature.</caption>

* following the removal of indwelling urinary catheter, in order to check the proper resumption of urination [35];

* in men with lower urinary tract symptoms. This population represents 30% of men over 60 years old [36]. Monitoring post-void residual over time allows to identify patients at risk of acute urinary retention [37] and to confirm chronic retention and/or overflow urinary incontinence [35];

* in patients with a neurological disease impacting bladder function, in particular multiple sclerosis [38].

Finally, when monitoring patients with a known voiding dysfunction, measurement of PVR can provide valuable information on the progression of the disease or the response to treatment [39].

It also reduces the risk of unnecessary catheterization and therefore the risk of urinary infection [40,41].

Slappendel and Weber observed a reduction in the catheterization rate after orthopaedic surgery from 31.4% to 15.9% by using a non-invasive PVR monitoring [41].

In a meta-analysis, the relative risk of developing a catheterization-related urinary infection was also reduced (OR = 0.27 IC95%[0.16-0.47]; P < 0.0001) [40].

The first BS (BladderScan BVI-2000®) was developed in 1986 [42]. BS are now commonly used in daily practice. Our review of the literature suggests that most bladder scanners exhibit similar precision. In addition, the difference in measurements compared to the gold standard method (catheterization) is not clinically significant, with average deviations of less than 50 mL.

Only one study in our analysis found that the precision of the two BS analyzed was insufficient, regarding the predefined limit of ±5% [22]. Nevertheless, one may question this 5% limit, especially for small volumes. Indeed, for volumes inferior <100 cm³, a difference of <5 cm³ of PVR has much less important clinical relevance.

Only two studies [32,43] used spontaneous voiding as the verification method, which may underestimate the accuracy of bladder volume measurement.

According to our research, it is also suggested that BS and conventional ultrasound systems overestimate low urine volumes and underestimate high filling volumes [44].

In the study of Brouwer et al., the mean measurement difference was 20 mL, which is not clinically significant insofar as the measurement
<table><caption>**Table 1**

Characteristics of the most frequent BS (Bladder Scanner) found in the PRISMA analysis of the literature.</caption><thead><tr><th></th><th>US frequency</th><th>Scan image</th><th>Scan angle</th><th>Bladder volume range</th><th>Accuracy*</th></tr></thead><tbody><tr><td>BVI 2500<br>Bladderscan</td><td>2 MHz</td><td>B-Mode</td><td>unknown</td><td>0-999 ml</td><td>0 to 699 ml: ±20%, ±20 ml<br>700 to 999 ml: ± 25%, ± 25 ml</td></tr><tr><td>BioCon 700<br>MCube</td><td>2.6 MHz</td><td>B-Mode</td><td>120</td><td>0-999 ml</td><td>±15%, ±15ml</td></tr><tr><td>BVI 3000<br>Bladderscan</td><td>2.12 MHz</td><td>V-mode</td><td>120</td><td>0-999 ml</td><td>0 to 699 ml: ± 20% ± 20 ml<br>700 to 999 ml: ± 25%, ± 25 ml</td></tr><tr><td>Padscan HD2<br>Caresono</td><td>3.5 MHz</td><td>B-mode</td><td>unknown</td><td>0-999 ml</td><td>±15%, ±15ml</td></tr><tr><td>VitaScan LT</td><td>3.4 MHz</td><td>B-mode</td><td>130</td><td>0-1000 ml</td><td>&lt;100 ml: ± 7.5ml<br>&gt;100ml: ± 7.5%</td></tr><tr><td>Biocon 900S<br>MCube</td><td>3.4MHz</td><td>B-mode</td><td>120</td><td>0-999ml</td><td>0-99ml: ±10ml<br>100-999ml: ±10%</td></tr><tr><td>Prime Plus<br>Bladderscan</td><td>2.53 MHz</td><td>B-mode</td><td>120</td><td>0-999 ml</td><td>&gt;100 ml ± 7.5 %<br>&lt;100 ml ± 7.5 ml</td></tr><tr><td>BVI 6100<br>Bladderscan</td><td>3.5 MHz</td><td>V-mode</td><td>120</td><td>0-999 ml</td><td>± (15 % ± 15 ml)</td></tr><tr><td>BVI 9400<br>Bladderscan</td><td>2.95 MHz</td><td>B-mode</td><td>360</td><td>0-999 ml</td><td>± (15 % ± 15 ml)</td></tr></tbody></table>

carried out retains its discriminatory nature to determine whether the bladder needs to be drained or not [22].

It should be noted that intra-observer measurement variability could not be assessed as not all of the studies included in this review have examined this particular aspect.

Several studies have suggested that the accuracy of BS measurement is not so much related to the BS itself but rather to the clinical situations at the time of the examination.

The impact of BMI in the quality of the measurement is probably linked to less precise identification of tissues due to the thickness of the abdominal wall, as with any ultrasound machine [19].

The postpartum period is suggested as a period at risk of measurement error due to changes in bladder shape induced by uterus growth [9,21,25]. Comparable issues were described with loco-regional modifications induced by prolapse, which can lead to volumetric estimation error [24].

<footnote>*scanning on a tissue-equivalent bladder Phantom</footnote>

<footnote>*Scanning on a tissue-equivalent bladder Phantom.</footnote>
<table><caption>**Table 2**
Summarizes the comparative studies between bladder scanners (BS) and urethrovesical catheterization.</caption><thead><tr><td>Study</td><td>Portable bladder US</td><td>Gender</td><td>Condition</td><td>N.</td><td>Mean volume difference estimate, ml (SD)</td></tr></thead><tbody><tr><td>Goode et al., 1990 (20)</td><td>BVI 2500</td><td>Females</td><td>Voiding dysfunction</td><td>95</td><td>17</td></tr><tr><td>Brouwer et al, 1999 (12)</td><td>BVI 2500</td><td>Males and females</td><td>Surgical patients</td><td>50</td><td>-19</td></tr><tr><td>Borrie et al, 2001 (11)</td><td>BVI 2500+</td><td>Males and females</td><td>Rehabilitation patients</td><td>167</td><td>-80.6 ± 111.2</td></tr><tr><td>Rosseland et al, 2002 (29)</td><td>BVI 2500 +</td><td>Males and females</td><td>Postoperative patients</td><td>36</td><td>-21.5</td></tr><tr><td>Demaria et al, 2003 (13)</td><td>BVI 3000</td><td>Females</td><td>Post partum</td><td>100</td><td>-42</td></tr><tr><td>Pallis et al, 2003 (21)</td><td>BVI 3000</td><td>Females</td><td>Post partum</td><td>27</td><td>130</td></tr><tr><td>Yu Hui et al, 2004 (6)</td><td>BVI 3000</td><td>Males and females</td><td>Voiding dysfunction</td><td>64</td><td>34.4 ± 38.2</td></tr><tr><td>Choe JH et al, 2006 (26)</td><td>BVI 3000</td><td>Males and females</td><td>Voiding dysfunction</td><td>89</td><td>3.6<br>7.8</td></tr><tr><td>Lukasse et al, 2007 (30)</td><td>BVI 6100</td><td>Females</td><td>Post partum</td><td>100</td><td>-26</td></tr><tr><td>Al Shaikh et al, 2009 (10)</td><td>BVI 3000</td><td>Females</td><td>Voiding dysfunction</td><td>101</td><td>-12.9</td></tr><tr><td>Park et al, 2011 (18)</td><td>BVI 3000<br>BioCon-500</td><td>Males and females</td><td>Voiding dysfunction</td><td>67</td><td>25.8<br>-25.9</td></tr><tr><td>Nusee et al, 2014 (14)</td><td>BVI 3000</td><td>Females</td><td>Post partum</td><td>190</td><td>15.7</td></tr><tr><td>Cho et al, 2017 (17)</td><td>Biocon 700</td><td>Females</td><td>Voiding dysfunction</td><td>125</td><td>23.59 ± 37.32</td></tr><tr><td>Theisen et al, 2018 (24)</td><td>Biocon 700</td><td>Females</td><td>Prolapse</td><td>70</td><td>5.94</td></tr><tr><td>Mulder et al, 2018 (16)</td><td>BVI 9400</td><td>Females</td><td>Post partum</td><td>404</td><td>-12.9 ml (± 178)</td></tr><tr><td>Brouwer et al, 2018 (22)</td><td>BVI 9400<br>Prime with pre scan<br>Prime without pre scan</td><td>Males and females</td><td>Surgical patients</td><td>318</td><td>21.8 (59.9)<br>-20.7 (70.1)<br>-20.7 (82.7)</td></tr><tr><td>Salimans et al, 2019 (9)</td><td>BVI 3000</td><td>Females</td><td>Post partum</td><td>25</td><td>312</td></tr><tr><td>Jensen et al, 2019 (25)</td><td>Biocon 700</td><td>Females</td><td>Post partum</td><td>50</td><td>-43.4 ± 117.4</td></tr><tr><td>Kamei et al, 2019 (19)</td><td>Lilium α-200</td><td>Males</td><td>Voiding dysfunction</td><td>15</td><td>8.1</td></tr><tr><td>Majima et al, 2020 (8)</td><td>Lilium α-200</td><td>Males and females</td><td>Voiding dysfunction</td><td>42</td><td>2.4 ± 52.0</td></tr><tr><td>Zheng et al, 2023 (31)</td><td>Unavailable data</td><td>Females</td><td>Post partum</td><td>70</td><td>42.7</td></tr></tbody></table>

Mean volume difference between bladder volumes derived from portable bladder ultrasound and from catheterization. When available, the standard deviation has been reported in brackets.
<table><caption>**Table 3**
Comparison between bladder scanners (BS) and the volume obtained from catheterization or spontaneous voiding.</caption><thead><tr><th></th><th>Population<br>n sex)</th><th>Sex</th><th>1 device</th><th>2 device</th><th>3 device</th><th>4 device</th><th>Verification<br>standard</th></tr></thead><tbody><tr><td>Ghani et<br>al (32)</td><td>50</td><td>Males<br>and<br>females</td><td>BVI 3000<br>(7.4 ml)</td><td>Bardscan<br>(-21.4 ml)</td><td>3D US<br>System*<br>(5.6 ml)</td><td>x</td><td>Spontaneous<br>voiding</td></tr><tr><td>Choe JH et<br>al (26)</td><td>89</td><td>Males<br>and<br>females</td><td>BVI 3000<br>(3.6 ml)</td><td>BME-150A<br>(7.8 ml)</td><td>x</td><td>x</td><td>Catheterization</td></tr><tr><td>Small et al<br>(33)</td><td>28</td><td>Males<br>and<br>females</td><td>BVI 3000<br>(16.7 ml)</td><td>BVI 6100<br>(38.4 ml)</td><td>iLook15<br>(-34.2 ml)</td><td>Bardscan<br>(-21 ml)</td><td>Spontaneous<br>voiding</td></tr><tr><td>Park et al<br>(18)</td><td>67</td><td>Males<br>and<br>females</td><td>BVI 3000<br>(25.8 ml)</td><td>BioCon-<br>500<br>(-25.9 ml)</td><td>x</td><td>x</td><td>Catheterization</td></tr><tr><td>Brouwer<br>et al (22)</td><td>318</td><td>Males<br>and<br>females</td><td>BVI 9400<br>(21.8 ml,<br>SD 59.6)</td><td>Prime with<br>pre-scan<br>(-20.7 ml,<br>SD 82.7)</td><td>Prime without<br>pre-scan<br>(-20.7 ml, SD<br>70.1)</td><td>x</td><td>Catheterization</td></tr></tbody></table>

Mean volume difference is reported in brackets.

* Conventional ultrasound.

In these specific situations, the operator should pay more attention to the patient medical history as well as repeat various confirmation measurements.

Other situations of measurement imprecision have been reported due to incorrect recognition by the BS [27,28].

The first BS models measured the volume automatically without direct visualization of the bladder, Today, most models are equipped with a screen displaying the ultrasound image and the location of the volume, which is measured in real time (RPI function: Realtime Prescan Imaging) [18].

This function is supposed to help the operator to recognize the presence of extra-vesal fluids, which could bias the measurement (cysts, intra-abdominal collections, diverticula, lymphoceles, etc.) and to better define the contours of the bladder.

Some of the most recent models offer a three-dimensional display of the bladder to further improve the accuracy of the measurement [45]. Integrated microprocessors aim to correct possible measurement errors, based on “deep learning” technologies [23].

The BVI 9400®, for example, offers a three-dimensional multispectral analysis which is supposed to improve the detection of the bladder and distinguish it from other pelvic organs such as the uterus [45]. These measurement tools would also make it possible to correct the inaccuracy linked to an irregular shape of the bladder or the mass effect of prostatic hyperplasia [18,46]. To our knowledge, there is no scientific evidence evaluating the improvement of these additional functions in volume measurement.

## 5. Conclusions

This review of the literature confirms that the BS analyzed were clinically reliable tools allowing a precise and fast estimation of bladder volume. No study found any difference in reliability between BS and catheterization, and between the different devices available. The main source of measurement bias was induced by clinical and anatomical conditions of the patients. Knowledge of the patient's medical history is crucial to better interpret the measurement result.

## Disclosure of interest

The authors declare that they have no competing interest.

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