Noninvasive bladder volume measurement

Point-of-care ultrasound in pediatric nephrology

Point-of-care ultrasound (POCUS) has evolved in recent years in clinical practice, helping in early bedside diagnosis of important etiologies. Many medical schools and training programs are integrating POCUS into their curriculum. Especially with the technological advances of newer handheld ultrasound devices, POCUS has now become a component adjunct to clinical examination, in the clinic and bedside in critical care units. The diagnostic utility of POCUS lies both in early identification of critical kidney disease, and also extra-renal pathologies from a focused cardiac ultrasound, lung ultrasound, and integrated fluid assessment. There is a need to incorporate POCUS in training in pediatric nephrology and establish competency standard criteria. This review shall cover how POCUS helps in enhancing patient care in pediatric kidney disorders and critical children, and the recent advances.

Novel Three-Dimensional Bladder Reconstruction Model from B-Mode Ultrasound Image to Improve the Accuracy of Bladder Volume Measurement

Traditional bladder volume measurement from B-mode (two-dimensional) ultrasound has been found to produce inaccurate results, and thus in this work we aim to improve the accuracy of measurement from B-mode ultrasound. A total of 75 electronic medical records including ultrasonic images were reviewed retrospectively from 64 patients. We put forward a novel bladder volume measurement method, in which a three-dimensional (3D) reconstruction model was established from conventional two-dimensional (2D) ultrasonic images to estimate the bladder volume. The differences and relationships were analyzed among the actual volume, the traditional estimated volume, and the new reconstruction model estimated volume. We also compared the data in different volume groups from small volume to high volume. The mean actual volume is 531.8 mL and the standard deviation is 268.7 mL; the mean percentage error of traditional estimation is −28%. In our new bladder measurement method, the mean percentage error is −10.18% (N = 2), −4.72% (N = 3), −0.33% (N = 4), and 2.58% (N = 5). There is no significant difference between the actual volume and our new bladder measurement method (N = 4) in all data or the divided four groups. The estimated volumes from the traditional method or our new method are highly correlated with the actual volume. Our data show that the three-dimensional bladder reconstruction model provides an accurate measurement from conventional B-mode ultrasonic images compared with the traditional method. The accuracy is seen across different groups of volume, and thus we can conclude that this is a reliable and economical volume measurement model that can be applied in general software or in apps on mobile devices.

Place de l’échographie clinique en médecine d’urgence

L’échographie clinique en médecine d’urgence (ECMU) devient une pratique intégrée à l’exercice de la spécialité. Quatre étapes semblent nécessaires au déploiement de cet outil : l’existence de preuves scientifiques sur sa pertinence clinique, l’implantation d’échographes dans les structures d’urgences (SU), la formation des médecins et l’objectivation d’un impact secondaire à son utilisation. Les preuves sur la pertinence diagnostique des techniques utilisées datent des années 1990 pour la majorité des applications utilisées aujourd’hui. La disponibilité d’un échographe adapté est également nécessaire. Si la majorité des SU disposent aujourd’hui d’un échographe, selon les recommandations françaises, toutes le devraient. Des échographes de mieux en mieux adaptés à la pratique de l’ECMU arrivent sur le marché. L’objectif doit être de permettre des examens rapides et fiables. Pour cela, une ergonomie épurée et l’implication de techniques d’intelligence artificielle semblent être l’avenir. Les médecins doivent également être formés. En France, l’utilisation de l’ECMU va se généraliser grâce à la formation de tous les nouveaux internes de médecine d’urgence. Cependant, beaucoup d’urgentistes exerçant actuellement doivent encore être formés. Pour répondre à cette demande, de nombreuses formations sont aujourd’hui accessibles. Enfin, peu de données sur l’impact clinique secondaire à l’utilisation de cet outil dans les SU sont disponibles. Après avoir défini l’ECMU, l’objectif de ce texte est d’expliquer la place de l’échographie clinique dans la spécialité de médecine d’urgence. Des perspectives d’évolution de l’ECMU sont également proposées.

Point-of-Care Ultrasound for the Pediatric Hospitalist's Practice

Point-of-care ultrasound (POCUS) has the potential to provide real-time valuable information that could alter diagnosis, treatment, and management practices in pediatric hospital medicine. We review the existing pediatric POCUS literature to identify potential clinical applications within the scope of pediatric hospital medicine. Diagnostic point-of-care applications most relevant to the pediatric hospitalist include lung ultrasound for pneumothorax, pleural effusion, pneumonia, and bronchiolitis; cardiac ultrasound for global cardiac function and hydration status; renal or bladder ultrasound for nephrolithiasis, hydronephrosis, and bladder volumes; soft tissue ultrasound for differentiating cellulitis from abscess; and procedural-guidance applications, including line placement, lumbar puncture, and abscess incision and drainage. We discuss POCUS applications with reviews of major pathologic findings, research gaps, the integration of POCUS into practice, and barriers to implementation.

Post-operative urinary retention: Review of literature

Postoperative urinary retention (POUR) is one of the postoperative complications which is often underestimated and often gets missed and causes lot of discomfort to the patient. POUR is essentially the inability to void despite a full bladder in the postoperative period. The reported incidence varies for the wide range of 5%-70%. Multiple factors and etiology have been reported for occurrence of POUR and these depend on the type of anaesthesia, type and duration of surgery, underlying comorbidities, and drugs used in perioperative period. Untreated POUR can lead to significant morbidities such as prolongation of the hospital stay, urinary tract infection, detrusor muscle dysfunction, delirium, cardiac arrhythmias etc. This has led to an increasing focus on early detection of POUR. This review of literature aims at understanding the normal physiology of micturition, POUR and its predisposing factors, complications, diagnosis and management with special emphasis on the role of ultrasound in POUR.

Pediatric emergency medicine point-of-care ultrasound: summary of the evidence

The utility of point-of-care ultrasound is well supported by the medical literature. Consequently, pediatric emergency medicine providers have embraced this technology in everyday practice. Recently, the American Academy of Pediatrics published a policy statement endorsing the use of point-of-care ultrasound by pediatric emergency medicine providers.  To date, there is no standard guideline for the practice of point-of-care ultrasound for this specialty. This document serves as an initial step in the detailed "how to" and description of individual point-of-care ultrasound examinations.  Pediatric emergency medicine providers should refer to this paper as reference for published research, objectives for learners, and standardized reporting guidelines.

Rapid focused neurological assessment in the emergency department and ICU

In the emergency and critical care setting, a comprehensive and thorough neurologic examination can be impractical. The clinical context should therefore focus the examination on those features relevant to acute diagnosis and management. This article discusses how to direct the history and examination in patients who have focal complaints, possible strokes affecting the anterior or posterior circulations, neck or back pain, neuromuscular complaints, global symptoms, or nonanatomic complaints.

Accuracy and precision of a new portable ultrasound scanner, the BME-150A, in residual urine volume measurement: a comparison with the BladderScan BVI 3000

The objective of the study was to determine the relative accuracy of a new portable ultrasound unit, BME-150A, and the BladderScan BVI 3000, as assessed in comparison with the catheterized residual urine volume. We used both of these machines to prospectively measure the residual urine volumes of 89 patients (40 men and 49 women) who were undergoing urodynamic studies. The ultrasound measurements were compared with the post-scan bladder volumes obtained by catheterization in the same patients. The ultrasounds were followed immediately (within 5 min) by in-and-out catheterizations while the patients were in a supine position. There were a total of 116 paired measurements made. The BME-150A and the BVI 3000 demonstrated a correlation with the residual volume of 0.92 and 0.94, and a mean difference from the true residual volume of 7.8 and 3.6 ml, respectively. Intraclass correlation coefficients for the accuracy of the two bladder scans were 0.90 for BME-150A and 0.95 for BVI 3000. The difference of accuracy between the two models was not significant (p = 0.2421). There were six cases in which a follow-up evaluation of falsely elevated post-void residual urine volume measurements on the ultrasound studies resulted in comparatively low catheterized volumes, with a range of differences from 66 to 275.5 ml. These cases were diagnosed with an ovarian cyst, uterine myoma, or uterine adenomyosis on pelvic ultrasonography. The accuracy of the BME-150A is comparable to that of the BVI 3000 in estimating the true residual urine volumes and is sufficient enough for us to recommend its use as an alternative to catheterization.

Prospective 3D ultrasonographic evaluation of immediate postpartum urine retention volume in 100 women who delivered vaginally

Our objective was to determine the reproducibility and validity of urine retention volumes measured by 3D ultrasonography (3D-US) 2 h postpartum. This was a longitudinal prospective study of 100 women who delivered vaginally. Each woman underwent five successive urine retention measurements with the Bladder Scan 2 h after vaginal delivery, followed by transurethral catheterization to determine the real volume. The reproducibility of only the last four scan values was analyzed with an intraclass correlation coefficient, and that of determinations 4 and 5 with a Bland-Altman plot. The validity of the device was similarly evaluated using the mean four-scan and real values. Pearson's correlation coefficient was calculated and a least-trimmed squares robust linear-regression model was used. All tests were two-sided with a 5% alpha risk. Results showed that 3D-US measurements were highly reproducible, with an intraclass correlation coefficient of 0.974 (95% CI:0.964-0.981). 3D-US also accurately estimated the real urine volume (intraclass correlation coefficient 0.924; 95% CI:0.888-0.949), but tended to underestimate by about 6.8%. The between-technique Pearson correlation coefficient was 0.94 (P < 0.0001) and the regression analysis gave an R2 of 0.914. Urine retention volumes exceeded 500 ml in 55 women, and 11 in 7. We concluded that 3D-US was reliably able to measure postpartum urine retention volume.

Renal ultrasound

Renal US is one of several imaging modalities available to the EP in the evaluation of patients with acute urologic disorders. It offers excellent anatomic detail without exposure to radiation or contrast agents but is limited in its assessment of renal function. It is an important alternative to helical CT scanning for evaluating renal colic, especially in children and pregnant women. It has an important role in excluding bilateral renal obstruction as the cause of acute renal failure. It is likely that Doppler renal US also will take on a prominent role in the evaluation of renal vascular disorders. It already has become the standard of care in the management of renal transplant patients. Bedside emergency renal US performed and interpreted by EPs with limited training and experience is increasing in use and gaining acceptance. At present, the primary role of renal US is to identify hydronephrosis in patients with renal colic or acute renal failure but, in the future, its role likely will expand as technology advances and its use increases. In many patients, bedside renal US may obviate the need for further diagnostic workup and speed the diagnosis and treatment of an emergency patient.

Magnetic resonance cystometry: accurate assessment of bladder volume with magnetic resonance imaging

OBJECTIVES

To evaluate magnetic resonance hydrometry for the calculation of bladder volume. The reference standard to assess bladder volume is urethral catheterization, which may be linked with the risk of trauma and infection. Hence, ultrasonography is the preferred diagnostic method. However, ultrasonography is investigator dependent and inaccurate in the hands of an inexperienced operator.

METHODS

Investigations were performed in a 1.0-Tesla clinical scanner with a manufacturer-provided single-shot turbo spin-echo sequence. We examined 30 healthy volunteers (21 males and 9 females) with a mean age of 26.4 years. To quantify the volume of fluid in a magnetic resonance image, a histogram algorithm was used and a calibration phantom applied. Prevoid and postvoid images were acquired. The bladder volume was calculated as the difference between the prevoid and postvoid image fluid volumes. The magnetic resonance-calculated data were compared with the actually voided volumes.

RESULTS

The measured voided bladder volume was 400 +/- 33 mL, whereas magnetic resonance hydrometry yielded 390 +/- 31 mL. The difference between both measurements was not statistically significant. The 95% confidence interval for the difference of both measurements ranged from -22.6 to 2.4 mL. The regression had an r2 of 0.97.

CONCLUSIONS

The feasibility of magnetic resonance hydrometry to quantify the bladder volume noninvasively was demonstrated.

Urinary retention in patients in a geriatric rehabilitation unit: prevalence, risk factors, and validity of bladder scan evaluation

The purpose of this study was to identify risk factors for urinary retention (UR) in frail, elderly patients, to determine its prevalence, and to assess the validity of the use of the BladderScan BVI 2500+ ultrasound scanner to measure postvoid residual urine volumes of > or = 150 ml. Probable UR was defined as two consecutive ultrasound scans with postvoid residual urine estimations of > or = 150 ml. The estimates were confirmed by in- and out-catheterization of actual postvoid residual urine (PVR). Risk factors for UR were the independent variables used in the regression analysis. Nineteen of the 167 people (11%) had UR. The risk of UR was greatest among patients who were older, or who were on anticholinergic medication, or who had diabetes of long standing, or who had fecal impaction. The correlation between paired scans and catheter volumes of > or = 150 ml was 0.87. The results suggest that the BladderScan BVI 2500+ ultrasound scanner, when used by trained nursing staff, provides conservative and valid estimates of PVR of > or = 150 ml in people undergoing geriatric rehabilitation.

Cystic pelvic pathology presenting as falsely elevated post-void residual urine measured by portable ultrasound bladder scanning: report of 3 cases and review of the literature

Dedicated portable ultrasound devices generally offer a rapid, noninvasive, largely operator-independent means of assessing post-void residual urine (PVR) volume. In most published series, PVR measured by portable ultrasound correlates well with catheterized urine volume. We report 3 cases in which follow-up of falsely elevated PVR measurements on ultrasound resulted in comparatively low catheterized volumes. In all 3 cases, the elevated readings were due to cystic ovarian pathology, which was diagnosed by formal radiologic evaluation and ultimately confirmed operatively in 2 cases. Cystic pathology of the pelvis or lower abdomen may present as an elevated PVR on ultrasound and low urine volume on subsequent catheterization and should prompt further evaluation.

Postoperative bladder distention: measurement with bladder ultrasonography

Bladder distention is a common postoperative occurrence. A process improvement project was conducted at a Midwestern Veteran Affairs Medical Center to determine whether a new method for detecting bladder distention, bladder ultrasonography, was more effective than manual palpation in the perianesthesia setting. Data were collected on 494 men over a 9-month period using bladder ultrasonography. Of those patients, 19.4% had postoperative bladder distention with greater than 400 mL of urine. This compared with 1.4% of patients who had bladder distention detected during the previous year using manual palpation. Data from the project supported the use of bladder ultrasonography as being more effective than manual palpation in the assessment of postoperative bladder distention in the PACU.

Measurements of organ volume by ultrasonography

In a clinical context, measurements of organ volume are often performed in the diagnosis and follow-up of patients with a variety of diseases. Ultrasonography is a cheap, widely available and non-hazardous imaging modality to use for estimation of volumes, and a range of two- and three-dimensional methods have emerged to accomplish this task. This paper reviews some of the ultrasound methods available in cardiology, gastroenterology, nephrology/urology and gynaecology/obstetrics. Using two-dimensional (2D) ultrasound, the simplest method of calculating the volume of an organ is based on the multiplication of three diameters perpendicular to each other. These 2D methods are often based on geometrical assumptions which may introduce significant errors in volume estimation. Therefore, volume estimation based on three-dimensional (3D) ultrasound has been developed to increase accuracy and precision. At present, the process of making 3D images based on ultrasonography is divided into five steps: data acquisition, data digitization, data storage, data processing and data display. In conclusion, ultrasonography is a useful and reliable tool to calculate volumes of organs. In particular, 3D ultrasonography seems promising in this respect and appears to be superior to 2D ultrasonography in accuracy and precision in volume measurements.

Three-dimensional ultrasound imaging

The objective of this article is to provide scientists, engineers and clinicians with an up-to-date overview on the current state of development in the area of three-dimensional ultrasound (3-DUS) and to serve as a reference for individuals who wish to learn more about 3-DUS imaging. The sections will review the state of the art with respect to 3-DUS imaging, methods of data acquisition, analysis and display approaches. Clinical sections summarize patient research study results to date with discussion of applications by organ system. The basic algorithms and approaches to visualization of 3-D and 4-D ultrasound data are reviewed, including issues related to interactivity and user interfaces. The implications of recent developments for future ultrasound imaging/visualization systems are considered. Ultimately, an improved understanding of ultrasound data offered by 3-DUS may make it easier for primary care physicians to understand complex patient anatomy. Tertiary care physicians specializing in ultrasound can further enhance the quality of patient care by using high-speed networks to review volume ultrasound data at specialization centers. Access to volume data and expertise at specialization centers affords more sophisticated analysis and review, further augmenting patient diagnosis and treatment.

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.

Evaluating measurement variability in clinical investigations: the case of ultrasonic estimation of urinary bladder volume

OBJECTIVE

To evaluate the quality of studies seeking to establish measurement properties (reliability and validity) of ultrasonic estimation of urinary bladder volume.

DESIGN

Online searching of the MEDLINE database between 1966 and 1995, and scanning of bibliography of known studies on ultrasonic bladder volume estimation. Study selection and study quality assessment were performed independently by two reviewers. Each article was evaluated for suitability of the reference standard, adequacy of reported blinding of the observers and appropriateness of the statistical index of concordance. The last two of these guidelines were applied to reliability studies (evaluating the relation among observed ultrasonic estimations), and all three guidelines were applied to validity studies (evaluating the relation of ultrasonic estimation with a definitive measurement).

POPULATION

One hundred and twenty-five participants enrolled in the five reliability studies and 769 participants in the 27 validity studies selected for appraisal of their quality.

MAIN OUTCOME MEASURE

Rate of study compliance with preset criteria for high quality.

RESULTS

None of the studies complied with all of the criteria for high methodologic quality. In the five reliability studies, investigators did not report adequate blinding of observers in three (60%) and an appropriate index of reliability was not used in any. Among the 27 validity studies, there was a lack of a suitable reference standard in 6 (22%), an inadequate blinding in 25 (93%), and an inappropriate index of validity in all (100%).

CONCLUSION

Based on our guidelines for quality assessment, a large proportion of studies on measurement properties was found to have inadequate methods, raising concern about the credibility of the reliability and validity estimates reported. These deficiencies highlight the lack of rigour employed in the design, conduct and analysis of reliability and validity studies, which has the potential for leading to patient mismanagement due to biases in the assessment of measurement variability in clinical investigations.

Implementing a bladder ultrasound program

Many patients admitted to an inpatient rehabilitation setting experience alteration in urinary elimination as a result of neurological changes. Urinary retention can develop due to hypotonic bladder, increased sphincter tone, absent or decreased sensation of bladder fullness, or urethral blockage. Incomplete bladder emptying can lead to such complications as urinary infection and incontinence. Rehabilitation nurses must assess patients for alterations in bladder emptying. The use of bladder ultrasound is one method now available for noninvasive measurement of bladder volume. In this article, the author reviews the implementation and results of a bladder ultrasound program at one rehabilitation facility.